ABSTRACTS: (Chronological)


REASSESSING FAUNAL DYNAMICS DURING THE GREAT AMERICAN BIOTIC INTERCHANGE USING UPDATED DATA AND ADJUSTMENTS FOR SAMPLING BIASES

LINDSEY, Emily, University of California – Berkeley, Berkeley, CA, USA; CARRASCO, Marc, University of California – Berkeley, Berkeley, CA, USA; BARNOSKY, Anthony, University of California – Berkeley, Berkeley, CA, USA; GRAHAM, Russell, The Pennsylvania State University, University Park, PA, USA

The Great American Biotic Interchange (GABI), which reached its peak around 2.5 MA following the formation of the Panamanian isthmus, resulted in a dramatic reorganization of mammal communities on the North and South American continents. Today, there are disproportionately more native North American mammal taxa surviving in both North and South America than there are taxa of South American origin on either continent. Previous studies have attributed this imbalance to differential in-situ speciation of native North American taxa following the Interchange, rather than differences in initial immigration success. However, these inferences are based on calculations of pre- and post- Interchange faunal dynamics using weak temporal controls and uneven spatial sampling. In addition, new research has improved our resolution of North American Pliocene fauna and shifted the boundaries for some North American Land Mammal Ages. To test the robustness of previous interpretations given those constraints, we re-evaluated analyses for late Cenozoic North American mammals using updated chronologies and taxon lists, and standardizing for time interval and sampling intensity using a variety of techniques. Total numbers of genera, originations and extinctions were 12%-46% higher using current data from the FAUNMAP II database than were previously reported. Standardization of this data by adjusting for temporal interval and number of localities results in relatively higher diversity and turnover rates in North American mammals in the Irvingtonian than was previously believed (the highest in any of the sampled time periods). These initial analyses support the idea that the GABI resulted in both increased turnover and initial increased diversity in North American mammals, and suggests that application of different methods to adjust for sampling biases will be useful in reconstructing details of this event.  

Journal of Vertebrate Paleontology 29 (Supplement to no. 3): 135A (2009)


ASSESSING THE HUMAN IMPACT ON MAMMALIAN SPECIES DIVERSITY DURING THE END-PLEISTOCENE EXTINCTION: CLUES FROM THE LAST 30 MILLION YEARS

CARRASCO, Marc A., BARNOSKY, Anthony D., University of California Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720

The relative weight of human impacts versus climate change as a cause of the end-Pleistocene extinction in North America has long been debated. Part of the difficulty in assessing the importance of each purported cause has been establishing a natural biodiversity baseline that takes into account the fluctuations of diversity in the presence of climate change but in the absence of humans through deep time. Here we use the MIOMAP and FAUNMAP databases of mammalian occurrences to clarify this baseline, as assessed by species-area curves, for the past 30 million years. We subject species-occurrence data to rarefaction and other sample standardization techniques and, in combination with the Berkeley Mapper software, derive species-area curves by geographic region for distinct time slices from the late Oligocene through the Holocene. Preliminary results indicate that mammalian species diversity, particularly in the northern Great Plains region, became severely depressed in the Holocene relative to every other time slice studied. These results suggest that the reduction in diversity across the Pleistocene-Holocene boundary was more excessive than had occurred for millions of years previously, lending support to ideas that invoke the presence of humans for the first time to explain the extinction. The case for coincident unusual events, such as out-of-the-ordinary glacial-interglacial warming or a purported comet impact, is less firm.

Journal of Vertebrate Paleontology 28 (Supplement to no. 3): 61A-62A (2008)


 

QUATERNARY EXTINCTIONS AND THE GLOBAL TRADEOFF IN MEGAFAUNA BIOMASS

 

BARNOSKY, Anthony, UC Museum of Paleontology, Berkeley, CA USA

 

It is now widely recognized that between 50,000 and 10,000 years ago, the Earth’s last great extinction event claimed two-thirds of all the largest mammal genera, and that one of the precipitating causes was the immigration of humans onto various continents and islands.  Among the human impacts thought to lead to megafuanal extinction are direct hunting (overkill), habitat disruption and fragmentation (for example, by setting fires), and introducing diseases, among others.  Little appreciated has been the potential ecological effects of increasing human population sizes to critical levels in a zero-sum global ecosystem.  To explore this I used population models constrained by archaeological and ecological observations to estimate human biomass and non-human megafauna biomass on Earth from human origins to the present.   These estimates suggest that initially, growth of human biomass approximately matched the loss of non-human megafauna biomass.  Then ~12 thousand years ago, as human biomass began its rapid rise, total megafauna biomass (counting humans as a megafauna species) crashed dramatically.  Recovery of megafauna biomass to pre-crash levels proceeded primarily by continued growth of human population, converting the global ecosystem to a new state where one species—humans—made up an inordinate amount of the world’s megafauna biomass.  Interestingly, pre-crash biomass levels were not attained until just prior to the Industrial Revolution, then they shot above the pre-crash baseline.  Exceeding the pre-crash baseline corresponded with adding energy to the global ecosystem by mining and using fossil fuels.  Implications include (1) a global ecological threshold event occurred with the megafuanal extinctions, after which humans became the dominant megafauna in a worldwide context; and (2) in the absence of developing alternative energy sources as fossil fuels are depleted, a near-future biomass crash that will unfavorably impact humans is inevitable.

Journal of Vertebrate Paleontology 28 (Supplement to no. 3): 48A (2008)


 

TIMING OF EXTINCTIONS AMONG LATE-PLEISTOCENE MEGAMAMMAL TAXA IN SOUTH AMERICA

 

LINDSEY, Emily, BARNOSKY, Anthony, University of California, Berkeley, Berkeley, CA, USA

 

The timing of the late-Quaternary megafaunal extinctions among different taxa and different geographic regions can provide crucial information about extinction models such as overkill versus ecological adjustment, and response of biota to late-Pleistocene climate change.  In order to determine the chronology of these extinctions in South America, we are compiling and evaluating the abundant radiocarbon dates that have been published for South American megafauna.  We have analyzed the last appearance dates (LADs) for a variety of megafauna species ranging geographically from Brazil to southern Patagonia.  Dates were ranked as to robustness using a modified Mead-Meltzer scale, incorporating criteria including type of material dated; strength of stratigraphic association; when and where the analysis was performed; and dating method (AMS vs. standard).  Dates were calibrated using OxCal4, with both the IntCal and and ShCal calibration curves for comparison.  We found that LADs reported for late-Pleistocene megafauna in South America in some cases appear much later than those for analogous taxa in North America.  We have found “reliable” South American LADs as young as 10166 cal BP for Smilodon; 9696 cal BP for horse; 8010 cal BP for sloth; and 7159 cal BP for glyptodont. Ecological analogs in North America were apparently all extinct before 11,300 cal BP.  There may also be geographic differences in timing of extinctions within the South American continent; so far, the youngest reported dates for extinct equid and xenarthran taxa all issue from the Southern Cone.  Given the very old dates reported for archaeological sites in southern South America (including Monteverde in southern Chile at 14,700 cal BP) and contemporaneous-to-earlier onset of late-Pleistocene climate changes relative to the Northern Hemisphere, these findings indicate a longer extinction window in South America than in North America, and suggests that whatever the cause of these extinctions, it was less abrupt in South America.

Journal of Vertebrate Paleontology 28 (Supplement to no. 3): 106A (2008)


USING THE FOSSIL RECORD TO DEFINE NATURAL BIODIVERSITY BASELINES IN MAMMALS

BARNOSKY, Anthony D., CARRASCO, Marc A., University of California, Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720

As global climate change and other human impacts accelerate ecological changes in the coming century, it is becoming more and more necessary to use the fossil record to define ecological baselines such that the true magnitude of future changes comes into focus. Here we examine the natural baseline of continental-level species richness in fossil mammals of North America, using data assembled from the MIOMAP and FAUNMAP databases of fossil mammal occurrences and associated geological and chronological information. We use rarefaction and other sample standardization techniques in combination with the Berkeley Mapper software to collate occurrence data into species-area curves for a variety of time-slices that vary in age from Miocene through Holocene. The fossil species-area curves are then compared with species-area curves derived from modern mammals, as obtained from zoology museum databases and subsampled to simulate fossil occurrences. Preliminary results demonstrate that for some geographic areas, notably the Great Plains, the Holocene species richness is depressed, suggesting a region-wide drop in species diversity as humans became more dominant in the ecosystem. We also identify differences between modern and pre-Holocene curves, although presently we are still trying to ascertain whether those differences are due to analytical artifacts or represent biological reality. By using the combination of fossil species area curves and modern ones we identify a range of variability that should bracket the extremes of species richness patterns that characterize landscapes little impacted by humans. Present or future species-area relationships that fall outside those limits indicate the extent to which human activity has perturbed natural systems.

33rd International Geological Congress , August 6-14, 2008


A DATABASE OF SOUTH AMERICAN QUATERNARY MAMMALS FOR PALEOECOLOGICAL ANALYSES

 

LINDSEY, Emily L.; BARNOSKY, Anthony D.,
University of California, Berkeley, United States

Although the dynamics of Quaternary extinctions are becoming better understood on most continents, the causes and effects of these events in South America remain ambiguous. To elucidate the relative roles environmental and anthropogenic stresses played in forcing the extinctions, and to facilitate investigations of community ecological response to these changes, we are constructing a database of late-Quaternary mammalian fossil remains relating taxonomic, geographical, stratigraphic and chronological information for the South American continent.  The database will incorporate detailed geographical information and precise AMS radiocarbon dates, and is designed to coordinate with existing North American databases such as FAUNMAP/NEOTOMA and MIOMAP, and related projects in Central and South America, including ZARSUD and the Mexican Quaternary Mammals Database.  The database will be served through the U.C. Museum of Paleontology at the University of California, Berkeley, and will form the basis for analyzing occurrences of taxa through space and time via integration with web-based mapping and analytical programs.  Spatio-temporal mapping routines, combined with biostratigraphic, paleoclimatic and archaeological analyses, will allow investigations of (a) patterns of extinction relative to latitude and elevation; (b) timing of extinctions relative to those in North America and other continents; (c) relationship of extinction events with paleoclimatic variation; (d) differential attrition rates of various taxa throughout South America; (e) potential anthropogenic impacts on megafauna populations; and (f) effects of environmental changes and taxa loss on subsequent mammalian community structure.  We are currently in the process of assimilating and evaluating all published radiocarbon dates on South American mammal fossils and identifying specimens and sites requiring additional and/or corroboratory dates.  So far we have compiled information on more than 40 sites in Chile and Argentina, and preliminary analysis of 14C dates suggests an extinction event that is younger than in North America and might well have extended into the Holocene. Results of future analyses will help us understand how climate change, human actions and other factors combine to force ecosystem changes on regional and global scales, and the extent to which the late Pleistocene can be used as an analog to forecast biodiversity loss in the current era of global warming and increasing anthropogenic pressures.

33rd International Geological Congress , August 6-14, 2008


 

See and Listen to the Talk

 

CLIMATE CHANGE, PEOPLE, AND DIVERSITY LOSS: GLIMPSING THE FUTURE THROUGH QUATERNARY MAMMAL EXTINCTIONS

 

BARNOSKY, A. D., Department of Integrative Biology and Museums of Paleontology and Vertebrate Zoology, University of California, Berkeley, CA 94720 USA

 

The two biggest environmental problems the world faces today are global warming and habitat fragmentation.  How will the combination of these two impacts change ecosystems on Earth?  A powerful perspective on that question emerges from setting the ecological changes of the past fifty years in the context of what is ‘natural’ as interpreted from the fossil record of life, then using that information to forecast ecological fates in the coming century. The last time Earth’s continents saw the intersection of events that were similar to, but much weaker than what is happening today, two-thirds of all the large terrestrial animals on Earth went extinct, significantly changing biodiversity patterns worldwide.  That was just prior to ten thousand years ago, when  increasing numbers of Homo sapiens were expanding their territory and as climate warmed from an ice age into our present interglacial.  Compilations of radiocarbon and other dates, and data from paleoecology, paleoclimatology, and archeology indicate that extinctions were most pronounced and rapid where accelerating human impacts and rapid climatic change coincided most closely in time.   Where there were only new human impacts, but no climate change, extinctions took place, but not necessarily suddenly.  Where there was climatic change in the absence of human impact, some local extinction occurred.  In some places, small mammal diversity decreased.  The evidence suggests that where human impacts didn’t affect diversity, climate change did—a one-two punch in the global context, although the intensity of each punch varied continent by continent.  This same kind of one-two punch, but with considerably more force, is underway today in the form of unprecedented global warming intersecting with precipitously declining natural habitats due to increasing numbers of humans.  The resulting biodiversity crash promises to be severe, this time plucking at the trophic and size levels that survived the late Quaternary event, and impoverishing our faunas, especially in nature reserves.

 

National Academy of Sciences Sackler Symposium, in the Light of Evolution: Biodiversity and Extinction, December 7-8, 2007

 


 

SPECIES-AREA CURVES & MORPHOCLIMATE MODELS AS TOOLS IN FORECASTING EFFECTS OF CLIMATE CHANGE ON VERTEBRATE COMMUNITIES

 

McGUIRE, Jenny, BARNOSKY, Anthony D., and CARRASCO, Marc A., Dept. of Integrative Biology and Museum of Paleontology, University of California, Berkeley, Berkeley, CA, USA

 

Anthropogenically induced global climate change, habitat fragmentation and species introductions all have potentially significant impacts on ecosystems. However, we currently lack robust models and metrics that enable us to identify critical climatic effects on the mammalian component of ecosystems, which in turn limits forecasting the ecological effects of climate change. As a first step it is critical to know if currently observed changes in mammalian biodiversity, species ranges, and species compositions are normal oscillations or anomalous events.  It is also critical to know the details of how climatic parameters affect the involved species. To address the first challenge we first take a macroecological approach and build species-area curves for selected time slices, using data from the MIOMAP and FAUNMAP databases. We use those curves to determine whether extant biodiversity is within normal past ranges and examine trends in past species richness. To better understand the relationship between climate and species distributions—which ultimately underlie any climatically-induced changes to biodiversity—we then focus on an ecologically important small mammal in California ecosystems, the California vole, Microtus californicus.  We develop what we term a morphoclimate model, which maps intraspecific morphological variation onto climate across space through time, while accounting for previously unaddressed cofactors including interspecific interactions and dispersal barriers.  This approach integrates data from geometric morphometrics as obtained from modern and fossil specimens with climate and paleoclimate models. Finally, through the combined use of species area-curves and morphoclimate models, we explore the ecological and evolutionary implications of climate change in explaining observed deviations from the “natural” baseline of mammalian biodiversity as it has fluctuated through thousands and millions of years.

 

17th Quadrennial Congress, International Union for Quaternary Research, Cairns, Queensland, Australia, 2007

 


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THE DEVELOPMENT OF A DATABASE COMPRISING THE LATE-QUATERNARY MAMMALIAN PALEONTOLOGICAL RECORD FOR SOUTHERN SOUTH AMERICA

 

LINDSEY, Emily, BARNOSKY, Anthony, University of California, Berkeley, Berkeley, CA, USA

 

A promising opportunity for evaluating the potential ecological impact of contemporary climate change is through analysis of ecological community response to the most recent major global climatic shift, i.e., the Pleistocene-Holocene transition. In North America, data from Quaternary mammalian sites are well documented and are assimilated in databases such as FAUNMAP (for the United States and Canada) and the Quaternary Mexican Mammals Database (for Mexico). However, no Quaternary fossil data set comparable in organization or scope yet exists for the South American continent, which hinders efforts to conduct intra- and intercontinental biogeographical analyses relating to ecological community changes during this period, particularly the extinctions of the Pleistocene megafauna and concomitant community shifts. In an effort to address such questions, we are establishing a database of late-Quaternary (late-Pleistocene to Holocene) mammalian fossils, including taxonomic, geographical, stratigraphic and chronological information, for Southern South America (Chile and Argentina). This database is intended to parallel FAUNMAP and to coordinate with the Quaternary Mexican Mammals Database and other ongoing efforts in Central and South America. We are in the initial stages of this project, which include 1) compiling faunal occurrences and associated information from published literature; 2) evaluating radiocarbon and other dates; 3) identifying areas from which additional records will be beneficial; and 4) establishing collaboration with other researchers interested in this effort. Such a database will facilitate investigations relating to the timing, logistics and causes of the end-Pleistocene megafaunal extinctions in this region, as well as allow comparisons between mammalian community responses to this ecological shift in North and South America.

 

Journal of Vertebrate Paleontology 27 (Supplement to no. 3): 106A (2007)

 


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USING SPECIES-AREA CURVES TO DEFINE THE LONG-TERM BIODIVERSITY BASELINE FOR NORTH AMERICAN MAMMALS

 

BARNOSKY, Anthony D., CARRASCO, Marc A., University of California Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720

The two biggest environmental problems the world faces today are global warming and habitat fragmentation. How will the intersection of these two impacts change ecosystems on Earth? A powerful perspective on that question emerges from setting the ecological changes of the past fifty years in the context of what is ‘natural' as interpreted from the fossil record, then using that information to forecast ecological fates in the coming century. Here we focus on defining the long-term baseline for species richness in mammals by tracking species-area curves through a variety of temporal and spatial scales in the USA. To build the curves, we use distributional data of modern mammals as recorded in field guides and museum collections and distributional data of fossil occurrences as recorded in the FAUNMAP and MIOMAP databases. We make the fossil and modern curves comparable by subsampling the modern data in a way to simulate fossil occurrences, then use the statistically adjusted counts of species per locality and area to construct species-area curves for a number of time-slices ranging in age from modern, to Holocene (back to 10 Ka), to Pleistocene (10 Ka to 1.8 Ma), and eventually back to the late Oligocene (as old as 30 Ma). Our preliminary results indicate that from late Pleistocene to present, species richness of small mammals declined uniformly across biogeographic regions from Pennsylvania to Texas. In the central Great Plains, modern habitat islands may retain characteristic late Holocene species richness of small mammals. These conclusions warrant further testing.

ESA /SER Joint Annual Meeting, August 5-10, 2007


 

ESTIMATING LATITUDINAL EFFECTS ON PALEODIVERSITY USING THE PALEODATABASE MIOMAP

CARRASCO, Marc A., University of California Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720

A latitudinal gradient in species richness, whereby species richness increases with decreasing latitude, has been well-documented among extant organisms. However, the discovery of this pattern in the fossil record has been more elusive given the vagaries (e.g., incomplete record, taxonomic and sampling biases) of paleontological data. Here we use the MIOMAP database of western North American mammals to assess how mammalian paleodiversity relates to latitude. Species lists were compiled for each quarter degree of latitude and subdivision of the North American Land Mammal Ages (Arikareean through Hemphillian) for the Great Plains, the region with the most complete fossil record. All resulting species richness numbers were rarefied to account for the species-area effect and sampling biases, such as uneven sampling, preservation biases, and the varying length of time bins. Preliminary results indicate that a latitudinal species gradient does exist, although the results lack significance given the incompleteness of the paleorecord. Further accumulation of fossil data and the application of more detailed methodologies should clarify whether the paleospecies-latitude relationship is robust and how it compares to the modern one.     

Geological Society of America Abstracts with Programs 38(7): 169-170 (2006)


THE ROLE OF VERTEBRATE PALEONTOLOGY IN FORECASTING FUTURE ECOLOGICAL CHANGE

BARNOSKY, Anthony, Univ. of California, Berkeley, CA

Sustaining ecosystem dynamics and services is one of the most critical issues facing humanity. There is now growing agreement that the information relevant to maintaining Earth’s ecological health can only be obtained through more seamless mergers of the detailed, near-time ecological record with the temporally longer, but more time-averaged, paleontological record. Vertebrate paleontology, though under-utilized in this regard, has much to offer, providing rich sources of data to: (a) differentiate significant anthropogenic effects on ecosystems from fluctuations that also occur in the absence of humans; (b) trace ecological metrics, such as species richness, through varying scales of space and time; (c) estimate and forecast the likelihood of species extinctions; and (d) diagnose trajectories towards abrupt transitions to alternative ecosystem states. Here I use data compiled from FAUNMAP, MIOMAP, individual Pleistocene and Miocene localities, and modern fauna of the American West to examine the ‘ecological baseline’ of mammalian communities at varying spatial and temporal scales. Methods include constructing species-area curves for various regions and time-slices, locally tracking species richness through time within size and trophic categories, and examining abundance patterns through time and space. Results are used to forecast how (or if) basic features of mammalian communities might be expected to change over the next century or so, given projected rates of global change.

Journal of Vertebrate Paleontology 26 (Supplement to no. 3): 39A-40A (2006)


CORRECTING FOR THE SPECIES- AREA EFFECT WHEN ESTIMATING PALEODIVERSITY

CARRASCO, Marc A., BARNOSKY, Anthony D., DAVIS, Edward B., Department of Integrative Biology, UC Berkeley, 3060 Valley Life Sciences Building, Berkeley, CA 94720

The impact of the species-area effect, the positive relationship between species richness and the area of geographic sampling, has been well-documented among extant organisms. However, the effects of this relationship on estimates of paleodiversity have never been fully explored, complicating our understanding of evolution, biogeography, and the response of ecosystems to climate change. We used the MIOMAP database of western North American mammals to assess how the species-area effect influences estimates of paleodiversity. Species lists were compiled for the entire USA and by geographic region for each of the fifteen subdivisions of the North American Land Mammal Ages from the Arikareean through the Hemphillian. All resulting species richness numbers were rarefied to account for sampling biases, such as uneven sampling, preservation biases, and the varying length of time bins. Using the online MIOMAP mapping program, the geographic area encompassed by each set of samples was calculated by plotting the points and drawing the area of the smallest polygon that would surround all of the samples per time bin. Plots of rarefied species versus geographic area revealed a clear species-area bias. We show how one can use these plots to correct traditional species diversity curves. Accounting for the species-area bias shows that only a few of the peaks and valleys in the mammalian paleodiversity curve remain. We investigate whether these peaks likely reflect biotic events or result from additional sampling biases in the mammalian fossil record, and then interpret how the remaining biodiversity peaks and valleys might relate to major tectonic and climatic events during the late Oligocene and Miocene.

Geological Society of America Abstracts with Programs 37(7): 461 (2005)


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MIOCENE MAMMAL MAPPING PROJECT (MIOMAP): AN ONLINE RELATIONAL AND SPATIAL DATABASE OF MIOCENE AND LATE OLIGOCENE FOSSIL MAMMALS

CARRASCO, Marc A., BARNOSKY, Anthony D., DAVIS, Edward B., KRAATZ, Brian P., University of California Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720

The Miocene Mammal Mapping Project (MIOMAP) database was created at the University of California at Berkeley and is now online (http://miomap.berkeley.edu) for use by the geosciences community. MIOMAP is a relational database built using Paradox 9.0 and includes all published mammalian vertebrate localities between 30 and 5 million years old (Arikareean through Hemphillian Land Mammal ages) from the western United States. Each locality entry is associated with a variety of data including quadrangle, latitude, longitude, relevant taxonomy, number of specimens, geologic age, depositional environment, taphonomic attributes, and bibliographic information.

For distribution on the world wide web, the MIOMAP database has been transferred into MySQL. Queries of the database can be made through HTML forms or an interactive map created using open source MapServer 4.0 software. Also, all data is downloadable in Microsoft Excel. Future additions include links to digital photos of type specimens and tools for spatial and other analyses of data. Current research using the database centers around understanding the effects of climatic and tectonic change on mammalian species diversity through time.

Geological Society of America Abstracts with Programs 36(5): 364 (2004)



MIOMAP REVISITED: A RELATIONAL AND SPATIAL DATABASE OF FOSSIL MAMMALS (ARIKAREEAN THROUGH HEMPHILLIAN) ON THE WORLD WIDE WEB

CARRASCO, Marc A.; BARNOSKY, Anthony D.; DAVIS, Edward B.; KRAATZ, Brian, University of California Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720

The Miocene Mammal Mapping Project (MIOMAP) database, under construction for the last five years at the University of California at Berkeley, is nearing completion and is now online for use by the vertebrate paleontology community. MIOMAP is a relational database designed for web-based distribution and incorporation into a GIS analytical tool (ARC/ INFO 8.3). Developed in Paradox 9.0 following the FAUNMAP data structure, MIOMAP has also been transferred into MySQL for online use. The database includes all published mammal species between 30 and 5 million years old from the western United States as well as well-identified, unpublished specimens represented by voucher specimens in museums. Information associated with each species occurrence includes latitude, longitude, relevant taxonomy and synonymies, geologic age, depositional environment, taphonomic attributes, bibliographic information, and, when available, numbers of specimens, among other relevant data. So far the database has been used for a variety of research applications involving (1) the effects of climatic change and tectonism on species richness and (2) the effects of applying different analytical techniques to determine species diversity patterns in the fossil record.

MIOMAP is currently accessible at http://miomap.berkeley.edu. Queries of the database can be made through a MySQL form or through a preliminary interactive map created using the Open Source Map Server software. In addition, all data is downloadable in several commonly used formats including Microsoft Excel, Paradox, and MySQL. Future additions to the web interface include: forms for the submission of new data or corrections to existing data, links to digital photos of type specimens, and full mapping and spatial analyses using a GIS interface.

Journal of Vertebrate Paleontology 24 (Supplement to no. 3): 44A-45A (2004)


 

EFFECTS OF TECTONIC ACTIVITY ON BETA DIVERSITY OF MAMMALS IN THE MIOCENE OF THE BASIN AND RANGE PROVINCE , WESTERN USA

DAVIS, E. B., A. D. BARNOSKY, and M.A. CARRASCO, Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, CA 94720

Ecological theory predicts that the taxonomic richness of a study area will be dependent upon geographic size (following species-area equations) and habitat heterogeneity, among other factors. Evolutionary theory predicts that areas that experience frequent vicariance, or that have abundant potential barriers to dispersal, will foster higher richness through formation of endemic species. Modern species richness in the Basin and Range Province of the southwestern United States is consistent with these predictions, demonstrating extensive endemism within basins, which leads to a higher richness for the province (beta diversity), while maintaining similar local (alpha) diversities to less fragmented areas. We hypothesize that this high beta diversity can be traced to the initiation of tectonic processes that formed the Basin and Range. In order to test this hypothesis, we compare beta diversity within the Basin and Range to that in the Great Plains through the last 15 Ma using published mammalian faunal records compiled in the MIOMAP and FAUNMAP databases. Preliminary analysis of species occurrence data, not accounting for sampling differences, indicates that Holocene beta diversity within the Basin and Range is higher than beta diversity at the onset of basin formation, while Miocene alpha diversity in the Basin and Range is consistently lower than in the Great Plains. These results support the theoretical predictions. However, differences in sampling and taphonomy preclude taking those results at face value; thus, we discuss methods of standardizing comparisons and calculating species accumulation curves for fossil data.

Journal of Vertebrate Paleontology 24 (Supplement to no. 3): 50A (2004)



ISOTOPIC DISCRIMINATION OF RESOURCE PARTITIONING AMONG UNGULATES IN C3 DOMINATED COMMUNITIES FROM THE MIOCENE OF
CALIFORNIA AND FLORIDA

FERANEC, R. S., Dept. of Integrative Biology, University of California, Berkeley, CA 94720 and MACFADDEN, B. J., Florida Museum of Natural History, University of Florida, Gainesville, FL 32611

Stable isotope analyses of mammal teeth are commonly used to examine resource partitioning in environments characterized by a mixture of C3 and C4 plants. However, isotopic discrimination of resource partitioning has rarely been shown in C3-dominated paleocommunities, even though analysis of modern ecosystems from Africa and North America has shown that this partitioning is detectable. We explored resource use and niche partitioning in three ancient, C3-dominated, Miocene communities from California and Florida: Barstow (CA), Blackhawk Ranch (CA), and the Love Bone Bed (FL), each of which predates the C4 global carbon shift 7 million years ago. 13C and 18O values were obtained from the tooth enamel of six ungulate genera from Barstow, eight from Blackhawk Ranch, and 14 from the Love Bone Bed. Results from 226 bulk isotope samples showed no significant differences among taxa at Blackhawk Ranch, but significant differences were observed among taxa within both the Barstow and Love Bone Bed localities. At each locality, equids generally had more positive 13C values, which suggests their use of more open habitats, while antilocaprids, camelids, and proboscideans had more negative values, implying residence in closed habitats. Notably Pediomeryx (Yumaceras) from the Love Bone Bed exhibited positive 13C values of, corroborating that more fiber, possibly grass, was incorporated into its diet, similar to the horses from the same locality. The lack of significant differences among taxa at Blackhawk Ranch may indicate either a relatively homogeneous flora, or presence of abundant resources permitting niche overlap, while the opposite is implied by the presence of significantly different isotope values among taxa at Barstow and Love Bone Bed. This study highlights the ability of this technique to discern resource partitioning for the millions of years before the C4 global carbon shift that occurred during the late Miocene.

Journal of Vertebrate Paleontology 24(Supplement to no. 3): 56A-57A (2004)


 

THE MECHANICS AND EVOLUTION OF FOSSORIALITY IN MYLAGAULID RODENTS: FUNCTIONAL AND ECOLOGICAL DIVERSITY IN A CLADE OF FOSSORIAL MAMMALS

HOPKINS , S.S.B. Museum of Paleontology and Dept. of Integrative Biology, University of California , Berkeley , CA , USA

Rodents of the family Mylagaulidae have long been recognized to be fossorial, based on their cranial and postcranial adaptations. However, this clade has defeated attempts at ecological classification, as a number of problematic features are inconsistent with modern fossorial rodents, especially those present in North America. In particular, the prominent nasal horns that diagnose one genus of mylagaulids, and the suggestion of their presence in several other mylagaulid clades, present difficulties in reconstructing the ecology of this group. No other fossorial mammals, extant or extinct, possess this characteristic, and given the importance of the head in fossoriality, it clearly indicates a unique ecology. Any statement about the ecology of this clade must therefore take this feature into account.

An examination of the biomechanics of the head and neck indicates that most mylagaulids differed from all extant North American fossorial mammals in that they used the snout extensively in digging, as do modern golden moles (family Chrysochloridae) and blind mole rats (genus Nannospalax) as well as the extinct proscalopid moles (family Proscalopidae). Most mammals employing this behavior are subterranean, rather than simply fossorial; most fossorial mammals are limited to scratch digging. Almost all mylagaulids have morphology consistent with this unusual digging mode; however, the horned mylagaulids (genus Ceratogaulus) may be an exception. A pattern of co-occurring species of horned and hornless mylagaulids through the mid- to late Miocene in the Great Plains
appears to result from the diversification of this clade to occupy fossorial as well as subterranean niches. It is possible that this ecological change played some role in the biogeographic patterns of mylagaulids and aplodontine aplodontids in the middle and late Miocene.

Journal of Vertebrate Paleontology 24 (Supplement to no. 3): 72A (2004)


 

TECTONIC ACTIVITY, THE SPECIES- AREA CURVE, AND SPECIES RICHNESS OF MAMMALS IN THE MIOCENE OF THE GREAT BASIN, USA

BARNOSKY, A.D., E.B. DAVIS, & M.A. CARRASCO, Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, CA 94720

Mammalian species richness fluctuated in the western United States through the Miocene. Here we examine whether changes were triggered by (a) climatic change; (b) tectonic activity; (c) species-area relationships as the Great Basin of the USA nearly doubled in size as a result of extensional tectonism; or (d) simply reflect sampling issues. We used the MIOMAP database to differentiate between these potential causes by comparing the timing and magnitude of changes in Miocene species richness in five discrete geographic regions: the Great Basin, the Rocky Mountains , the Pacific Northwest , the northern Great Plains , and the southern Great Plains . We predicted that if tectonic events drove the species richness patterns, increases in richness should be coincident and of greatest magnitude in the northern Rocky Mountains and Great Basin. If climate change was the driver, changes should be approximately coeval and of similar magnitude in all geographic areas. If continental-area and the species-area curve are most important, the main increase should center on the Great Basin after the middle Miocene. After accounting for sampling biases in the data, we found a complex pattern of species richness among these areas that does not rule out tectonic activity as being important in driving species richness patterns in the western USA.

Conference Proceedings of the 32nd International Geological Congress, Florence , Italy (2004)


 

MULTIVARIATE ANALYSIS OF HEMPHILLIAN ANTILOCAPRID ASTRAGALI FROM NORTHWESTERN NEVADA REVEALS SIZE PARTITIONING BETWEEN ILINGOCEROS AND SPHENOPHALOS

DAVIS, E. B., Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, CA 94720

Although restricted to a single species today, antilocaprids enjoyed a great diversity in the Miocene. Two species of antelope, Sphenophalos nevadanus and Ilingoceros alexandrae, of the Thousand Creek local fauna (early early Hemphillian, Humboldt Co., NV) are represented by an extensive number of horn cores, individual cheek teeth, and abundant podial elements. The species have very different horn morphologies, but are seemingly indistinguishable based on other skeletal elements. Recent work on ecologically similar but unrelated African antelope has indicated that ecological differences between species affect the morphologies of their astragali. To test this hypothesis in the two fossil species, I measured eight aspects of 60 astragali from UCMP locality 1100, the type locality of S. nevadanus. Principal components analysis reveals differences in shape that separate the astragali into two groups. One group is similar to modern Antilocapra in shape, but is much smaller. The fossil specimens when lumped together exhibit a much greater CV than in modern Antilocapra. These results confirm that at least two fossil species are present, and hint at ecological differences between the two.

PaleoBios 24 (Supplement to no. 1.): 2 (2004)


 

PHYLOGENETIC SYSTEMATICS OF APLODONTOID RODENTS

HOPKINS , S.S.B. Museum of Paleontology and Dept. of Integrative Biology, University of California , Berkeley , CA , USA

The clade Aplodontoidea, composed of the families Mylagaulidae and Aplodontidae, is one of the most widespread and diverse groups of rodents in the late Oligocene and Miocene of North America. This clade diverged from basal rodent stocks (Ischyromyidae and Paramyidae) in the Eocene, and diversified widely during the Oligocene and early Miocene, but then declined from the mid-Miocene through the present, where they are represented by only a single species, Aplodontia rufa. This clade provides an ideal opportunity to study the life history of a clade on the rise and in decline. The present study uses cladistic methodology to reconstruct the phylogenetic history of all described and several undescribed species of aplodontoid rodents. The phylogenetic analysis includes a matrix of 96 Operational Taxonomic Units (OTUs) and 316 characters, including all cladistically applicable characters published as distinguishing species of aplodontoids.

The resulting phylogenetic hypothesis, while poorly supported in many branches, makes it possible to recognize several important points about the relationships among aplodontoids. First, the subfamilial groupings are upheld as monophyletic groups with fairly strong support, with the exception of the basal Prosciurinae, which was expected to appear as a basal “wastebasket” taxon. Second, the Mylagaulidae appear to be paraphyletic, in that the Aplodontinae, including the still-extant Aplodontia, nest within the family Mylagaulidae; mylagaulids also nest deeply within the Aplodontidae, and hence are better described as subfamilies (Mylagaulinae and Promylagaulinae) within the Aplodontidae. It is also apparent that there are several paraphyletic genera designated, for two different reasons: Some are described on the basis of plesiomorphies, and are hence “paraphyletic by intent.” Several others appear to be “relictually paraphyletic” in that previously described species were not always included in the description of new genera with which they had phylogenetic affinity. Finally, this phylogenetic analysis of all aplodontoids makes it possible to recognize a series of major changes in the ecological role of this clade through evolutionary time.

PaleoBios 24 (Supplement to no. 1): 4 (2004)


 

PHYLOGENETIC ANALYSIS OF CLIMATE TOLERANCES INDICATES CLIMATE-DRIVEN SPECIATION WITHIN MARMOTA (ROTENTIA: SCIURIDAE)

DAVIS, E. B., Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, CA 94720

Several recent debates have centered upon whether mammalian species originate in response to changing climate. I address this question by examining patterns of climatic tolerances of extant species in the rodent genus Marmota. Specimens assigned to this genus are common in the fossil record. If new species originate through allopatric invasion of new climate regimes, their climatic tolerances should show a poor fit to their evolutionary history. Alternatively, if new species originate within the same climatic regime as their parent species, their climatic tolerances should fit well with their evolutionary history.

To test these hypotheses, the relationship between geographic distribution, climatic tolerance, and phyologeny was examined for extant species of the rodent genus Marmota. ArcInfo was used to transfer range maps of the 14 species to a GIS
containing 2.5° latitude/ longitude data of monthly temperature and precipitation averages. Average temperature and precipitation values for the species were then compared to the published molecular phylogeny. Comparisons were made using UPGMA and Neighbor Joining methods to construct dendrograms that represent climate affinity between the species.

Neither climate dendrogram showed a topology similar to the phylogeny. Three pairs of species appear in both dendrograms. The evolutionary tree shows M. caudata and M. menzbieri to be sister species, M. olympus and M. vancouverensis to be a paraphyletic group, and M. broweri and M. camtschatica to be from two different subclades on two different continents. A regression of climate distance against published distances from the maximum likelihood phylogeny indicates a significant positive correlation (p=0.043); however the R2 value (0.045) is very low, reflecting the poor nature of the fit. These results support the hypothesis that species of Marmota were originating through allopatric invasion of new climate regimes; also, they imply that climate influences mammal species formation, and that the geographic distribution of fossil species may hold a climatic signal. Additional work in other groups is necessary to determine whether this pattern persists.

Journal of Vertebrate Paleontology 23 (Supplement to no. 3): 44A (2003)


 

HYPSODONTY AND NICHE PARTITIONING IN APLODONTOID RODENTS: DO SMALL HERBIVORES PARALLEL UNGULATES DURING MIOCENE DIVERSIFICATIONS?

HOPKINS , S.S.B. Museum of Paleontology and Dept. of Integrative Biology, University of California , Berkeley , CA , USA

The trend toward increasing hypsodonty and associated diversification in Miocene large herbivores has been the subject of abundant recent research. While the patterns of change in large herbivores are becoming well-understood, few studies have examined evolutionary changes in small herbivores during the same time interval, essential to building a complete picture of ecosystem dynamics through time. This study examines changing hypsodonty and evolutionary radiation in a lineage of small herbivores, the Aplodontoidea, and asks two questions. First, do small herbivores show the same patterns of ecomorphological change as large herbivores? Second, how does this change affect niche partitioning and competitive interactions within the lineage? I constructed a species-level phylogeny of aplodontoid rodents and used it to study changes in ecomorphology through time within the lineage.

Aplodontoid ecomorphology undergoes several changes through the 35 million years the lineage persists, and those changes seem to correlate with changes in habitat through the Oligocene and Miocene. While Oligocene aplodontoids are relatively small, brachydont, and postcranially unspecialized, by the early Miocene the clade is dominated by hypsodont forms. Middle and Late Miocene aplodontoids are all large, fossorial, and extremely hypsodont. These morphological changes parallel those in large herbivores.

Competitive interactions were assessed using patterns of co-occurrence of aplodontoid species drawn from the Miomap database. The relatively low dispersal capability of the modern species would suggest that sister taxa of aplodontoids in the fossil record should occur in close geographic proximity; however, this expectation does not seem to hold. Preliminary analysis of phylogenetic divergence between co-occurring species suggests that the clade generally differs from the expectation inferred from extant aplodontid ecology, and that sister species generally do not occur in close proximity, particularly after their Oligocene radiation. The level of phylogenetic divergence between co-occurring species suggests competition may be preventing sympatry of closely-related species.

Journal of Vertebrate Paleontology 23 (Supplement to no. 3): 62A (2003)



EFFECTS OF CLIMATE ON MAMMALIAN SPECIES DIVERSITY AND
COMMUNITY STRUCTURE DURING THE TERTIARY IN THE NORTHERN GREAT PLAINS , UNITED STATES

CARRASCO, Marc A. and FERANEC, Robert S., University of California Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720

We examined the effects of climate change on mammalian species diversity and community structure from 30 to 9 million years ago in the northern Great Plains. Species records were acquired from the MIOMAP database, a relational database of western North American fossil mammals that is currently under construction at the University of California, Berkeley. All records were from a limited geographic range (southeastern Wyoming, southern South Dakota, and northern Nebraska ) and separated into 11 time intervals based on currently accepted subdivisions of the North American land mammal ages. The effect of climate change on species richness was evaluated by comparing the global oxygen isotope curve to a species diversity curve corrected for sampling bias. Changes in community structure were assessed by qualitatively comparing mammalian body mass distributions (cenograms) from successive time intervals to each other as well as to the oxygen isotope curve. Our results suggest that: (1) contrary to prior reports, changes in species diversity in the northern Great Plains do appear to relate to shifts in the oxygen isotope curve, (2) no clear relationship was found between climate change and community structure, and (3) a shift from a more open, arid habitat to a more forested, humid environment appears to have occurred during the Mid-Miocene Climatic Optimum.

Geological Society of America Abstracts With Programs 35(6): 418 (2003)


 
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ASSESSING MAMMALIAN PALEOFAUNAL DIVERSITY: DISCREPANCIES BETWEEN PUBLISHED AND MUSEUM COLLECTION DATA FOR THE MIOCENE OF NORTHWESTERN NEVADA , USA

DAVIS, E. B. and N. PYENSON, Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, CA 94720

Many paleobiological database projects, e.g. MIOMAP and the Paleobiology Database, allow researchers to investigate large-scale ecosystem dynamics through meta-analyses of published fossil records, addressing questions concerning the interplay between organismal and environmental change. Published records are the foundations of these projects; however, in many cases they may not adequately reflect the composition of fossil deposits, possibly confounding meta-analyses. Here we address the gap between the published record and the fossil record by examining the vertebrate fossil collections at the University of California Museum of Paleontology (UCMP), focusing on the Miocene mammal fossils from the Virgin Valley and Thousand Creek regions of northwestern Nevada . The fossil collections are compared to published data to assess similarity of diversity, relative abundance, and evenness, using rarefaction analyses, cenograms, and taxonomic similarity comparisons. Initial results indicate a discrepancy between the published data and actual museum collections. For example, published data for a sample Thousand Creek locality indicate the presence of eight genera, while a survey of the museum collections indicates the presence of 13 genera. Similarly, a sample Virgin Valley locality has 11 published genera and 15 genera represented in collections. These differences in generic richness are reversed when comparable numbers of specimens are compared through rarefaction analysis, probably because the original researchers were interested only in the best-preserved specimens for taxonomic purposes, leading to a much steeper rarefaction curve. These results show that data published by early workers are not comparable to the more intensive studies published today, which lends credence to an additional layer of bias in paleontological records. Database projects would benefit from research programs with an emphasis on investigation and publication of all collected fossil material.

Geological Society of America Abstracts With Programs 35(6): 498 (2003)


 

PARALLEL ADAPTIVE RADIATIONS IN FOUR LINEAGES OF APLODONTOID RODENTS: A CASE STUDY IN THE EVOLUTION OF HYPSODONTY

HOPKINS , S.S.B. Museum of Paleontology and Dept. of Integrative Biology, University of California , Berkeley , CA , USA

The evolution of high-crowned teeth, or hypsodonty, is well studied in a variety of large mammals. It is generally attributed to consumption of grasses, increased grit on food due to the spread of open habitats, or both. Similar trends toward increasing tooth crown height are present in several small mammal lineages; however, they have been left out of most discussions of the evolution of hypsodonty. There are good reasons for this exclusion; differences between large and small mammals in diet, life span, and other aspects of life history mean the causes of increasing tooth crown height may be different for small mammals. Nevertheless, the nearly simultaneous increase in hypsodonty in several lineages of large and small mammals suggests some commonality of causation.

This study focused on several lineages of small mammals in the clade Aplodontoidea (including rodents from the families Aplodontidae and Mylagaulidae), to determine whether the trends toward increasing hypsodonty in four lineages within this clade show a common evolutionary pattern. The four lineages included in this study are the subfamilies Meniscomyinae, Allomyinae, and Aplodontinae, and the family Mylagaulidae. These four lineages are of roughly the same rank within the larger clade, and are monophyletic with respect to one another, diverging from a brachydont common ancestor. Divergence time, time of maximum diversification, degree of development of hypsodonty, lineage duration, and morphological diversity were compared among the four groups. It appears that all these clades diverged in the late Oligocene, and all increased in hypsodonty at about the same time. However, there are substantial differences between lineages in time of peak diversification, degree of hypsodonty, lineage duration, and morphological diversity. It appears that the dissimilarity between clades in diversification patterns may be due to autecological differences between members of the various clades. Despite these ecological differences, for these small mammals, as in previously studied large herbivores, there appears to be simultaneous, parallel trends toward increasing tooth crown height. Such consistency in evolutionary trends between independent lineages suggests a common causation.

Geological Society of America Abstracts with Programs 34(7): 418 (2003)



CLIMATIC CHANGE, HUMAN IMPACTS, AND
THE LONG-TERM BIODIVERISTY BASELINE FOR MONTANE MAMMALS

BARNOSKY, Anthony D., University of California Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720

Despite the importance of biodiversity analyses in ecology and conservation biology, we know little about what is "natural" for biodiversity over long time spans (>thousands of years). Neither do we know whether biological communities are inherently stable, and if so, what scale of environmental perturbation shifts them off of their normal baseline. To address these questions, diversity characteristics of mammal communities from the high Colorado Rocky Mountains were established for several slices of time: a middle Pleistocene glacial >780,000 years old, a middle Pleistocene interglacial >600,000 years old, historic time just prior to modern human influence, and the late 20th century. The middle Pleistocene data are from an exceptionally rich sequence of fossil deposits in Porcupine Cave , located in South Park , and allow assessment of climatic influence on mammals in the absence of humans. The historic and modern data are from published accounts and field observations of mammals that occur within a 12.5 km radius of the fossil site. Comparison among the time slices of species richness sorted by higher taxonomic, trophic, and size categories: (1) defines the long-term biodiversity baseline; (2) suggests functional community stability persisted >600,000 years, despite marked climate changes and species turnover; and (3) highlights that human and climatic impacts on communities are fundamentally different, the former affecting large carnivores and herbivores first, and the latter starting at lower size and trophic categories. An important implication is that monitoring species richness within communities may be a simple yet effective guideline for assessing ecosystem health.

Symposium on Biodiversity: Past, Present, and Future, Proceedings of the American Association for the Advancement of Science, Pacific Division, 22(I): 41 (2003)


 
EFFECTS OF QUATERNARY CLIMATIC CHANGE ON SPECIATION IN MAMMALS

BARNOSKY, Anthony D., University of California Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720

An ongoing controversy in evolutionary biology is the extent to which climatic changes drive evolutionary processes. On the one hand are "Red Queen" hypotheses, which maintain that climatic change is less important than biotic interactions in causing evolutionary change. On the other hand are "Court Jester" models, which recognize climatic change as a very important stimulus to speciation. The Quaternary, characterized by multiple climatic changes in the form of glacial-interglacial transitions, offers a fertile testing ground for ascertaining whether cyclical climatic changes that operate at the 100-thousand year time scale appreciably influence evolutionary patterns in mammals. Despite the increased potential for isolation of populations that should occur with multiple advances and retreats of glaciers and rearrangement of climatic zones, empirical data suggests that speciation rates were neither appreciably elevated for Quaternary mammals, nor strongly correlated with glacial-interglacial transitions. This suggests that if climatic change does influence speciation rates, it does so over time scales longer than a typical glacial-interglacial cycle.

Symposium on extinctions and speciation during the Quaternary. Sixteenth International Quaternary Association Congress, Reno , Nevada , July 23-30, 2003




INFLUENCE OF COLLECTION METHODS ON ASSESSMENTS OF PALEOCOMMUNITY ECOLOGY: A CASE STUDY FROM THE EARLY MIOCENE OF WYOMING

HOPKINS , S.S.B. Museum of Paleontology and Dept. of Integrative Biology, University of California , Berkeley , CA , USA

Numerous recent studies in vertebrate paleontology have focused on reconstructing the ecology of terrestrial fossil communities. Large collections of specimens from stratigraphically well-resolved sites are often used to study change in community structure through time. One of the biggest impediments to such studies is that taphonomy alters the composition of fossil assemblages relative to the faunas from which they are derived. While most taphonomic biases can only be recognized, and not removed, collecting procedure is a preventable source of taphonomic bias. Collection bias can significantly alter the composition of a collected assemblage relative to the one present in the rocks. This study endeavors to determine how large an influence collection method has on analyses of community structure. The data set used to address this question is a sample of roughly 4800 vertebrate specimens from the early Miocene Split Rock local fauna, which was collected both by surface picking and screenwashing. Results indicate that the species richness values derived from the two different methods are fairly similar; however, the structure of the reconstructed community is dramatically changed by the method of collection. Also, the relative proportions of specimens collected by the different methods has a strong influence on the reconstructed community structure, although species richness is again not strongly influenced by this factor. When change through time in community structure is considered, these problems are magnified by changes in proportions of specimens collected by different methods. It is clear that changes in the mode of collection can have large effects on our assessment of how ecology has changed though time. Accounting for collection methods will make it possible to get a clearer picture of paleocommunity ecology.

Geological Society of America Abstracts with Programs 34(6): 35 (2002)



MAMMALIAN BIOGEOGRAPHIC PATTERNS DURING THE EARLY BARSTOVIAN (MIDDLE MIOCENE) IN THE WESTERN UNITED STATES

CARRASCO, Marc A., University of California Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720

Today, western North America can be divided into distinct biogeographic provinces based on unique assemblages of mammals, which can then be grouped into distinct superprovinces and regions. However, it is unclear if the relationships among these provinces are the result of recent events (Pleistocene to Recent) or are more deeply rooted in Earth's history (Miocene). To test these hypotheses, generic occurrences of mammalian taxa during the early Barstovian (15.9 to 14.8 million years ago) were tabulated from the literature and extracted from the MIOMAP database for seven geographic regions: California Coast, Pacific Northwest , Northern Rocky Mountains , Great Basin , Southern Great Basin, Colorado Plateau, Northern Great Plains , and Southern Great Plains . Region boundaries were chosen such that they closely corresponded to recognized extant mammalian biogeographic provinces. The data were analyzed using two methodologies: a parsimony analysis of endemicity ( PAE ) and a cluster analysis using the coefficients of communities between provinces. The resulting trees suggest that the relationships we see today among mammalian biogeographic provinces were not identical to those of the early Barstovian. Similarities include a Great Basin/Pacific Northwest clade and a Colorado Plateau/Northern Great Plains grouping. On the other hand, during the early Barstovian the Northern Rocky Mountains showed a closer affinity to the Southern Great Basin than to the Colorado Plateau, and the Southern Great Plains was markedly different from all other provinces, perhaps reflecting a coastal adapted fauna. Further study of the Clarendonian and Hemphillian faunas is currently underway in hope of refining when these shifts in biogeographic patterns occurred.

Journal of Vertebrate Paleontology 22 (Supplement to no. 3): 42A (2002)


 

EFFECTS OF LATE MIOCENE COOLING WITHIN A NEVADA INTERMONTANE BASIN REVEALED BY PALEOECOLOGICAL ANALYSIS OF THE VIRGIN VALLEY AND THOUSAND CREEK MAMMALIAN FAUNAS

DAVIS , E. B., Museum of Paleontology and Dept. of Integrative Biology, University of California , Berkeley , CA , USA

The Virgin Valley (Barstovian) and Thousand Creek (Hemphillian) local faunas of northwestern Nevada were used to examine the relative effects of late Miocene cooling on the ecology of a single basin. These faunas accumulated before (Virgin Valley) and within (Thousand Creek) the dramatic late Miocene cooling indicated by the global oxygen-isotope curve. Analyzed data included information from all published localities at Virgin Valley and Thousand Creek as well as the unpublished collections in the UCMP. Preliminary results indicate that taxonomic diversity increases between Virgin Valley and Thousand Creek, with species diversity rising from 17 to 25 taxa. Generic diversity increases from 19 to 24, and familial diversity increases from 16 to 19 taxa. Rarefaction analyses based upon number of specimens indicate that species and generic diversities increase but familial diversity remains unchanged, indicating an increase in species with no increase in lineage diversity. Rarefaction analyses based upon number of localities sampled also indicate an increase in species diversity; however, these rarefaction analyses suggest both generic and familial diversity did not change between the two local faunas. Despite potential biases that might influence the diversity analyses (e.g. the better publication record for Thousand Creek), marked changes in the faunal composition between the two localities indicate an ecological shift. Virgin Valley is dominated by the equid Merychippus and the palaeomerycid Dromomeryx indicating a moderately open habitat. Thousand Creek is dominated by the antilocaprids Sphenophalos and Ilingoceros, which indicate more closed habitats. The nature and extent of faunal change are consistent with environmental change influencing ecological patterns.

Journal of Vertebrate Paleontology 22 (Supplement to no. 3): 48A (2002)


 

KEY ADAPTATIONS CREATING ECOLOGICAL GENERALIZATION THROUGH MORPHOLOGICAL SPECIALIZATION: EVIDENCE FROM HYPSODONTY AND STABLE ISOTOPES

FERANEC, R.S. Museum of Paleontology and Dept. of Integrative Biology, University of California , Berkeley , CA , USA

Key innovations are evolutionary changes in individual traits that are causally linked to an increased diversification rate in the resulting clade. These key innovations may indicate increased specialization (narrowing of ecological niche) or expansion of the suite of lifestyles available to an organism (increasing niche breadth). Hypsodonty provides a unique example of a key adaptation that can test whether the adaptation indicates ecological specialization or generalization. Hypsodonty has been noted as a key innovation for the Equidae, and may have been a key innovation for various other ungulate taxa, as well. The evolution of hypsodonty generally has been interpreted as a specialization from a grazing niche into a browsing niche. Here I test whether this assumption holds true by analyzing the feeding strategy of various ungulates, particularly equids. If hypsodonty does represent a morphological specialization resulting in ecological specialization, it would be expected that hypsodont taxa have a more specialized diet than do brachydont taxa. Variation in the carbon isotope ratio reflects the proportions of C3 or C4 forage in the diet of ungulates, and can be used to indicate a more specialized or generalized diet. Following, because ecological specialists are more prone to extinction, it would be expected that hypsodont taxa have a shorter species life span than brachydont taxa.

The stable carbon isotope data shows that individuals of hypsodont taxa, (Bison, Equus, Mammuthus) generally display a wider range in diet than those individuals of brachydont taxa (Odocoileus, Mammut). This suggests that hypsodont taxa are capable of feeding on a more generalized diet than brachydont taxa. There appears to be no correlation between hypsodonty and species life span within the Equidae. A pattern from long-lived to short-lived species occurs before the evolution of hypsodonty, species become more long-lived with the advent of hypsodonty, then become more short-lived afterwards. This pattern within the Equidae is consistent with expectations if hypsodonty created ecological generalization. Hypsodonty does not appear to be strictly associated with obligate grazing and a specialized diet; instead it appears to represent an adaptation that widened niche breadth to allow grazing as well as browsing.

Journal of Vertebrate Paleontology 22 (Supplement to No. 3): 52A (2002)



DYNAMICS OF MAMMALIAN COMMUNITY STRUCTURE AND
TAXONOMIC RICHNESS THROUGH A MAJOR CLIMATIC WARMING EVENT INFERRED FROM THE FAUNA OF THE MIOCENE CABBAGE PATCH FORMATION, MONTANA

HOPKINS , S.S.B. Museum of Paleontology and Dept. of Integrative Biology, University of California , Berkeley , CA , USA

Recent human-induced climate changes have generated interest in the paleoecological consequences of faunal change. Studies of faunal change across periods of past major climate transitions may inform our understanding of the possible outcomes of current global warming. One potentially informative past climate change occurred around 25 million years ago, near the Oligocene-Miocene boundary. An excellent system for studying the faunal changes associated with this event is present in the Arikareean fauna of the Cabbage Patch Formation of western Montana , which was well-collected and studied by Don Rasmussen. The Cabbage Patch strata produce abundant fossil remains of terrestrial vertebrates, invertebrates, and plants, and the stratigraphy is well-resolved, providing a temporal context in which to study changes in the fauna. I studied the structure of the mammalian community through time, in order to determine whether the large scale changes in the physical environment, which occurred throughout the time spanned by the deposit, were accompanied by changes in community structure. Patterns of community structure through time were compared with patterns of taxonomic diversity, a measure typically used to determine faunal response to climate change. For each stratigraphic level, taxonomic richness and relative abundance were computed. To quantify community structure, taxa were placed in guilds as inferred from morphology and phylogeny. Also, body size structure in the community was determined for each stratum. The data were analyzed across strata in order to determine whether significant changes occurred through the several million years spanned by the deposit. Preliminary analyses show significant changes in species composition, particularly among geomyoids and aplodontids, although simple taxonomic richness does not appear to change. Also, the structure and ecological composition of the community appears to undergo substantial change through the period studied. These results suggest that dramatic changes may occur in the structure and composition of communities with changes in the physical environment, even though taxonomic richness may not change much.

Journal of Vertebrate Paleontology 22 (Supplement to no. 3): 67A (2002)


 

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ASSESSMENT OF MAMMALIAN SPECIES RICHNESS IN THE NORTHERN GREAT PLAINS , NORTHERN ROCKY MOUNTAINS, AND PACIFIC NORTHWEST DURING THE EARLY ARIKAREEAN

BARNOSKY, Anthony D. and CARRASCO, Marc A., Museum of Paleontology and Dept. of Integrative Biology, University of California, Berkeley, CA, USA

Patterns of species richness in space and time reflect (a) the underlying ecological processes that assembled a particular group of species and (b) the sampling procedure and analytical methods used to calculate diversity. Separating what aspects of diversity patterns arise from biological processes (signal) versus methodology (noise) in paleontological deposits is especially vexing, because taphonomic pathways and collecting techniques seldom are identical from site to site. Yet interpreting species diversity from fossil data sets is essential to understanding what is "natural" for biodiversity patterns today. To more reliably determine how to extract biological signal from methodological noise in fossil data, we used the MIOMAP database to analyze mammalian species richness through the early Arikareean (Miocene) in three biogeographic regions (northern Great Plains , northern Rocky Mountains , and Pacific Northwest ). We employed several techniques, including uncorrected counts of species, standardizing for time averaging in various ways, rarefaction, bootstrapping, and using a "rosetta stone" approach that compares only sites with similar sample sizes and taphonomic history. The results demonstrate that different interpretations of species richness patterns result from different ways of treating the data. This underscores the need for simultaneously applying the regional database and rosetta stone approaches to obtain the most reliable conclusions about species diversity in the fossil record.

Journal of Vertebrate Paleontology 21 (Supplement to no. 3): 31A (2001)



THE NEAREST-LIVING-RELATIVE METHOD OF PALEOCLIMATE RECONSTRUCTION: TESTING THE ASSUMPTIONS WITH SPECIES OF THE RODENT MARMOTA

DAVIS , E. B., Museum of Paleontology and Dept. of Integrative Biology, University of California , Berkeley , CA , USA

The nearest-living-relative method is often used in extracting paleoclimate information from fossil assemblages. One of its primary assumptions is that there is a phylogenetic control on the climatic tolerances of evolving lineages. This assumption is critical but rarely is tested. If it holds true, then correlations should exist between cladograms that reflect evolutionary history and multivariate data that reflect relationships between climate spaces of taxa under consideration. This study applies a phylogenetic approach to explore the relationship between climatic features (such as maximum and mminimum January and July temperatures, annual precipitation, and seasonality) and evolution of extant species within Marmota (the marmots and woodchucks). Species within this genus are potentially important paleoclimatic indicators because of their relatively restricted geographic distribution and habitat requirements and their abundance in certain fossil deposits. The association between a phylogenetic hypothesis based on molecular data and multivariate climatic parameters, both derived from published records, was tested using several methodologies, including Felsenstein's independent contrast method. The technique involved mapping the climatic tolerances of various species onto the hypothesized phylogenetic relationships and thereby determining if groups of species were delineated by identifiable climatic boundaries. In addition, the relative distances between taxon-defined multivariate climate space were compared to the evolutionary distances between taxa to determine if the amount of climatic difference between given taxa corresponded to their taxonomic distance.

Preliminary results do not support a correlation between phylogeny and climatic tolerances for the analyzed Marmota species. Further work is needed in order to fine-tune these methods and better explore the relationship between climate and mammalian evolution.

Journal of Vertebrate Paleontology 21 (Supplement to no. 3): 43A-44A (2001)


 

PRELIMINARY PHYLOGENETIC ANALYSIS OF APLODONTID RODENTS REVEALS HISTORY OF REPEATED HOLARCTIC IMMIGRATIONS

HOPKINS , S.S.B. Museum of Paleontology and Dept. of Integrative Biology, University of California , Berkeley , CA , USA

Aplodontid rodents today are represented by a single extant species, Aplodontia rufa, but they have a particularly extensive and diverse fossil record in the late Oligocene and Miocene of North America and Eurasia. The biogeographic history of the group is undoubtedly complex, as several genera span multiple continents, and there appear to have been several immigration events between North America and Eurasia. This very complexity, combined with the diversification and decline of the group, suggests that aplodontid history can provide a rich study system for addressing a variety of paleoecological and evolutionary questions. However, interpreting the biological process underlying aplodontid distributional patterns has been hindered by uncertainty about intrafamilial relationships between genera. Previous studies have relied upon non-cladistic methodologies for the reconstruction of phylogeny. The rapid evolution of molar morphology in aplodontids complicates application of cladistic techniques, because the differences between genera are often dramatic and homologous characters are difficult to identify. Here a first attempt at phylogenetic interpretation is presented, focused around understanding the evolutionary and biogeographic relationships of a new mid-Miocene (late Barstovian) aplodontid from Hepburn's Mesa, Park County, southwestern Montana . This new phylogenetic reconstruction shows that the Hepburn's Mesa material falls within the Ansomyinae, a group previously known only from Eurasia. Ansomyines are unique among aplodontids as a brachyodont lineage in the mid-Miocene. This group is sister to the taxon that includes the Allomyinae, Meniscomyinae, Aplodontinae, and Mylagaulidae, which are the groups that took part in the radiation of hypsodont aplodontids in the late Oligocene and were the most abundant aplodontid clades in the mid-Miocene. After the mid-Miocene, aplodontid diversity declined gradually, both in North America and in Eurasia, with only the single modern representative in the Pacific Northwest after the end of the Pleistocene.

Journal of Vertebrate Paleontology 21 (Supplement to no. 3): 63A (2001)


 

DO MAMMALIAN DIVERSITY PATTERNS IN THE WESTERN UNITED STATES HAVE TEMPORALLY DEEP ROOTS?

BARNOSKY, Anthony D. and CARRASCO, Marc A., Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, California, USA

How stable are large-scale diversity patterns? To examine this question we compared mammalian diversity patterns through time in three physiographic regions of the United States: the northern Great Plains, the northern Rocky Mountains , and the Pacific Northwest . Our goal was to assess whether the diversity patterns we see today reflect (1) a transient snapshot of ever-changing diversity patterns; (2) influence mainly by Pleistocene glacial-interglacial cycles; or (3) roots in deep time, which are only slightly overprinted by more recent influences. Accordingly, we focused on three slices of time: the early Miocene (about 24 to 30 million years ago, appropriately subdivided), the late Pleistocene (~40 to 10 thousand years ago), and the present. Species-occurrence data were extracted from the newly developed MIOMAP database and the FAUNMAP database to determine paleo-patterns, which were then compared with published information on modern diversity patterns. Although sampling problems greatly complicate the analysis, we found that the three biogeographic regions probably have retained some integrity for at least 30 million years, despite tectonic events and climatic changes. From this we infer a "diversity baseline" against which future observations of diversity changes can be compared to assess the degree to which natural systems are perturbed.

Scientific Program and Abstracts, 8th International Theriological Congress, Sun City, South Africa, p. 33 (2001)


 

MIOMAP: A RELATIONAL AND SPATIAL DATABASE FOR RESEARCH ON EVOLUTION, ECOLOGY, AND BIOGEOGRAPHY OF MIOCENE MAMMALS

BARNOSKY, Anthony D. and CARRASCO, Marc A., Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA USA

The Miocene Mammal Mapping Project (MIOMAP) has the primary goal of casting light on the question: How do large-scale physical-environmental perturbations affect the evolution and biogeography of mammals? The intent is to apply the fossil record to help delineate what is natural for the mammalian component of ecosystems in order to more accurately assess the environmental effects of human induced global change.MIOMAP is a relational database in PARADOX 9 designed for incorporation into a GIS analytical tool (ARC/ INFO 8.0). It includes all published Miocene mammal species of the United States, and as time and resources allow, will also include well-identified, unpublished specimens represented by voucher specimens in museums. Information associated with each species occurrence includes latitude, longitude, relevant taxonomy, geologic age, depositional environment, taphonomic attributes, bibliographic information, and numbers of specimens, among other relevant data. The data structure parallels that for the FAUNMAP project, with which complete compatibility is envisioned. A later phase of the project also calls for exploring interfaces that would easily link MIOMAP with other relevant datasets. The immediate research application of MIOMAP is to test hypotheses about how global warming and a tectonic event ~17 Ma ago affected faunal turnover, species richness, and biogeographic patterns in the western U.S. Analyses so far have focused on comparisons of the Pacific Northwest, Northern Rockies , and northern Great Plains . Preliminary results indicate that alpha diversity and faunal turnover rates in the northern Rockies may have increased as a result of the environmental perturbations and that beta diversity may have remained the same or decreased. However, the results highly depend on analytical method. In addition, the three areas seem to have retained biogeographic integrity throughout the Miocene intervals that were studied; modern biogeographic patterns may therefore be deeply rooted in time.

PaleoBios 21 (supplement to no. 2): 28 (2001)


 

A PHYLOGENETIC EXAMINATION OF THE NEAREST-LIVING-RELATIVE METHOD FOR RECONSTRUCTING PALEOCLIMATE AT MAMMALIAN FOSSIL LOCALITIES

DAVIS , E. B., Museum of Paleontology and Dept. of Integrative Biology, University of California , Berkeley , CA , USA

Overlapping climatic tolerances of extant taxa are commonly used in paleoclimate reconstruction. This method is limited by the stratigraphic ranges of living taxa. Paleoclimate hypotheses have been extended deeper in time through assuming that the nearest living relatives of extinct taxa provide appropriate climatic analogs. These methodologies implicitly assume that the climatic tolerances of taxa do not change through time, and the nearest-living-relative method assumes that there is a phylogenetic control on the climatic tolerances of evolving lineages.

The assumptions of the nearest-living-relative methodology can be tested for mammal lineages through a phylogenetic analysis that examines the association of various important climatic parameters with various taxa. Accordingly, this study applied a phylogenetic approach to understand the relationship between climatic features (such as maximum and minimum January and July temperatures, annual precipitation, and seasonality) and evolution of extant species within Marmota and Microtus. Species within these genera have been considered important paleoclimate indicators due to their abundances, distinctive dental characters, and present restriction to certain microhabitats. The association between phylogenetic hypotheses based on molecular data and climatic parameters, both derived from published records, was tested using Felsenstein's independent contrast method. The technique involved mapping the climatic tolerances of various species onto the hypothesized phylogenetic relationships and thereby determining if groups of species were delineated by identifiable climatic boundaries.

Preliminary results indicate a correlation between phylogeny and climate tolerances for Microtus species endemic to North America. If additional analysis substantiates these results, the nearest-living-relative method could prove to be an important tool in reconstructing the paleoclimates of some fossil mammal localities.

PaleoBios 21 (Supplement to no. 2): 44-45 (2001)


PHYLOGENY OF THE APLODONTIDAE (MAMMALIA:RODENTIA) AND SOME IMPLICATIONS FOR OLIGO-MIOCENE BIOGEOGRAPHY

HOPKINS , S.S.B. Museum of Paleontology and Dept. of Integrative Biology, University of California , Berkeley , CA , USA

Aplodontid rodents today are represented by only a single extant species, Aplodontia rufa, but they have a particularly extensive and diverse fossil record in the late Oligocene and Miocene of northwestern North America. Extensive studies of North American aplodontids, particularly those from the John Day basin of Oregon, have indicated relatively rapid in situ evolution of molar morphology within genera. Less forthcoming have been intrafamilial relationships between genera, in part because cladistic methods have not previously been applied to interpreting the systematics of the group. Here a first attempt at phylogenetic interpretation is presented, focused around understanding the evolutionary and biogeographic relationships of a new mid-Miocene aplodontid from Hepburn's Mesa , MT. The new species differs greatly in both size and cusp morphology from other material known from the Miocene of North America, which is limited to derived, hypsodont forms, such as Allomys and Liodontia. A phylogenetic reconstruction of aplodontid relationships shows that the Hepburn's Mesa material falls within the Ansomyinae, a group previously known only from Eurasia. This group is sister to the taxon that includes the Allomyinae, Meniscomyinae, Aplodontinae, and Mylagaulidae, which are the groups that took part in the radiation of hypsodont aplodontids in the late Oligocene and were the most abundant aplodontid clades in the mid-Miocene. The relationships among aplodontid groups suggest that several higher taxa, including the Prosciurinae and the Meniscomyinae, may be paraphyletic. The phylogeny also has implications for the biogeographic history of aplodontids, as they appear to have immigrated multiple times between Europe, Asia , and North America in the Oligocene and Miocene. With the cessation of this immigration in the mid- to late Miocene and the extirpation of aplodontids from Asia and Europe, aplodontids and mylagaulids began to decline in diversity, and were reduced to the single extant species by the late Pleistocene.

Paleobios 21 (Supplement to no. 2): 67 (2001)



EFFECTS OF CLIMATIC AND TECTONIC PERTURBATIONS ON MAMMALIAN COMMUNITIES

BARNOSKY, Anthony D. and CARRASCO, Marc A., Museum of Paleontology and Department of Integrative Biology, University of California , Berkeley

Numerous opinions exist about the importance of environmental perturbations in causing major changes in the mammalian component of a given ecosystem. Studies that focus on large geographic (continental) scales and long temporal scales (millions of years) tend to demonstrate little correlation between climate change and mammalian species turnover. As the scales resolve to local sites over decades, centuries, or millennia, however, some species clearly appear and disappear. We explore this dichotomy of scale by examining how mammalian evolution and biogeography responds to perturbations that take place on the hundred-thousand to million year time scale, and on geographic scales that are larger than a single site but within appropriately restricted physiographic and climatic zones. The methods include compiling all mammal records of Miocene age in the U.S. A Geographic Information System (ARC/ INFO ) and other statistical techniques are used to determine how closely species turnover patterns correlate on a region-by-region basis with the timing of the mid-Miocene climatic optimum (~17 Ma), and with tectonic activity in the Northern Rocky Mountains and Great Basin . Preliminary results suggest that in response to climatic warming and/or tectonic activity in the northern Rocky Mountains 18.5-14.0 Ma., mammalian species richness possibly increased there, faunal turnover was pronounced, and taxa adapted to warm, arid environments became more abundant in numbers of species and density of individuals. The data are consistent with the environmental change driving evolutionary and ecosystem change at sub-continental spatial scales and temporal scales that exceed typical Milankovitch oscillations.

Eos, Transactions, American Geophysical Union 81(48): F201 (2000)


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MIOMAP: A GIS -LINKED DATABASE TO ASSESS THE EFFECTS OF TECTONIC AND CLIMATIC CHANGES ON MAMMALIAN EVOLUTION

CARRASCO, Marc A. and BARNOSKY, A. D. University of California Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720

We present preliminary results of a 3-year project to build a detailed database of all terrestrial mammal occurrences in the United States from 30 to 5 million years ago. The three main goals of the project are: (1) to use the information to test hypotheses about how climate change and tectonic activity drive mammalian evolution; (2) to make the data available to the scientific community through a web site; and (3) attempt to develop interfaces that allow exchange of information with other existing large-scale database efforts. The MIOMAP database closely parallels the FAUNMAP database in its use of a relational database program to enter data (PARADOX 9) and use of ARCINFO 8 as the GIS tool. The data will consist of published information and, where identifications are of high quality, unpublished specimens contained in major museum collections. We invite investigators with high-quality, unpublished data to contact us if they feel their data should be included in the effort. The first few months of work have concentrated on the faunas of Wyoming, Montana , Idaho , Oregon , and South Dakota . Preliminary results suggest that: (1) sample coverage in these states is good for early Arikareean, moderate for late Arikareean, poor for Hemingfordian especially the late Hemingfordian, and variable for the Barstovian and Clarendonian; (2) species richness corrected for sampling effort does not undergo major changes through the Arikareean, but a Hemingfordian peak in the Rockies may be real; and (3) changes in faunal composition seem to correlate with major excursions of the oxygen isotope record.

Geological Society of America Abstracts with Programs 32(7): A-15 (2000)



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MIOMAP: A GIS -LINKED DATABASE FOR ASSESSING EFFECTS OF ENVIRONMENTAL PERTURBATIONS ON MAMMAL EVOLUTION AND BIOGEOGRAPHY

BARNOSKY, Anthony D. and CARRASCO, Marc A., University of California Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720

We present early results of a 3-year project to build a detailed database of all terrestrial Miocene mammal occurrences in the United States . The main goals of the project are three-fold: (1) to use the information to test hypotheses about how environmental perturbations such as climate change and tectonic activity drive (or do not drive) mammal evolution and distribution; (2) to make the data available to the scientific community through a web site based at the UCMP; and (3) insofar as is possible, to develop interfaces that allow exchange of information with other existing large-scale database efforts. The MIOMAP database closely parallels the FAUNMAP database in definition of data tables, use of a relational database program to enter data (currently PARADOX 9), and use of ARCINFO 8 as the GIS analytical tool. The data will consist of published information and, where identifications are of high enough quality, unpublished specimens contained in some major museum collections. We invite investigators with high-quality, unpublished data to contact us if they feel their data should be included in the effort. The first few months of work have concentrated on the faunas of Wyoming, Montana, Idaho, and Oregon. Preliminary results suggest that: (1) sample coverage in these states is good for early Arikareean, moderate for late Arikareean, poor for Hemingfordian, and relatively good for Barstovian; (2) species richness corrected for sampling effort does not undergo major changes through the Arikareean, but a Hemingfordian peak in the Rockies may be real; and (3) changes in faunal composition seem to correlate with major excursions of the oxygen isotope record.

Journal of Vertebrate Paleontology 20 (Supplement to no. 3): 28A (2000)

 

Use of this resource in publications should be cited as:
Carrasco, M.A., B.P. Kraatz, E.B. Davis, and A.D. Barnosky. 2005. Miocene Mammal Mapping Project (MIOMAP). University of California Museum of Paleontology http://www.ucmp.berkeley.edu/miomap/