NAPC 2001
June 26 - July 1 2001 Berkeley, California
Abstracts, Ag - An
(5/17/01)
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THE SIGNIFICANCE OF HIGHLY VARIABLE CONCENTRATIONS
OF DECAPOD FINGERS: A COMPARISON OF THE PALEOECOLOGY, TAPHONOMY, AND SEDIMENTOLOGY
OF SEVERAL AMERICAN NEOGENE DEPOSITS
AGNEW, Jeffrey G., Dept. of Geological Sciences, University of Florida,
Gainesville, FL, USA; Roger W. Portell and Douglas S. Jones, Florida Museum
of Natural History, University of Florida, Gainesville, FL, USA; and Carol
M. Tang, California Academy of Sciences, San Francisco, CA, USA
A number of studies have documented the taphonomy and
infrequent occurrence of whole-bodied decapods, with various explanations
being offered for their preservation or lack thereof. However, little
research has been conducted on the ubiquitous and often abundant decapod
cheliped segments in shelly deposits. Such remains represent nearly all
of the known decapod taxa from the Neogene of Florida and considerably
more taxa are waiting to be identified. Even less is understood about
the taphonomic, paleoecological, and sedimentological context of deposits
with decapod fingers. The circumstances that lead to the destruction of
whole-bodied crabs may favor the preservation of their heavily calcified
and highly resistant fingers. Therefore, any model of decapod taphonomy
should encompass all states of preservation and not just the most extraordinary.
Do unusual densities of decapod chelipeds require unique
environmental conditions that allow for their preservation or do they
simply reflect large populations? Of course, it seems probable that both
are required, but whether one exerts a greater influence over the other
is uncertain. This presentation explores specific factors that may control
the occurrence, abundance and condition of decapod fragments in shell
beds and other deposits. The paleoecology, taphonomy, and sedimentology
of nine shell beds in a Plio-Pleistocene section from south-central Florida
with an unusually dense concentration of decapod fingers is compared to
other formations with differing abundances of decapod parts. These include
select deposits from the Miocene of northwest and north-central Florida
and the Dominican Republic, the Pliocene of southern Florida, and the
Pleistocene of Baja California, Jamaica, and southern Florida. The influence
that seagrass, callianassid shrimp, sediments, and depositional processes
have on the occurrence and preservation of decapod parts will be discussed.
NEW FINDINGS OF CAPRINID RUDISTS (BIVALVIA-HIPPURITACEA)
IN THE CERRO DE LABRADORES, STATE OF NUEVO LEÓN, MÉXICO
AGUILAR, Javier P., and Yolanda B. Pichardo, Facultad de Ciencias de
la Tierra, Universidad Autónoma de Nuevo León, México
The Cerro de Labradores is located in the west central part of the State
of Nuevo León, and belongs to the northeastern part of the Sierra
Madre Oriental. The reefal facies of the Cupido Formation (Imlay, 1937)
outcrops in vast areas of this region. This lithological member was identified
by Padilla-Sánchez (1978), noting the abundance of monopleurid,
requienid and caprinid rudists, associated with oysters, fragments of
corals and other organisms. Johnson (1984) made a detailed study of the
lagunal facies of the Cupido and El Abra Formations, describing the requienids
at specific levels. The authors found in this locality many specimens
of the following species of caprinid rudists: Amphitriscoelus waringi
Harris and Hodson, Caprina douvillei Paquier, Praecaprina varians
Paquier and Offneria simplex Chartrousse and Masse. The last three
species are reported for the first time from Mexico. These speciesare
also present in other localities of the American Province of the Tethys
Realm, like Trinidad, Venezuela, Cuba and Texas. Amphitriscoelus waringi
is an endemic species of this province. The other three species exist
also in the Mediterranean Province of the Tethys Realm. The four species
are well known as indicative of early Aptian age. On the other hand, the
sedimentary sequence of the Cupido Formation, which is lower Aptian, was
already determined by Padilla-Sánchez (1978, 1982) on the basis
of the presence of Nannoconus bermudezi Kamptner and N. elongates
Bronnimann.
LOWER TERTIARY LARGER FORAMINIFERA FROM PAKISTAN
AKHTAR, Muhammad, Geological Survey of Pakistan, Lahore, Pakistan; and
Aftab A. Butt, Institute of Geology, Punjab University, Lahore, Pakistan
Age-diagnostic benthonic larger foraminifera have been recorded mainly
from the Upper Paleocene and the Lower Eocene succession represented dominantly
by the carbonate platform deposits. The Middle Eocene in northern Pakistan
is essentially a red bed facies with some fossiliferous interbeds. This
sequence is overlain by a stratigraphic unit developed as bank facies.
Stratigraphically important foraminiferal species are Miscellanea miscella
(d'Archiac & Haime), Lockhartia haimei (Davies), Lockhartia
tipperi (Davies), Lockhartia conditi (Nuttall), Ranikothalia
sindensis (Davies), Ranikothalia nuttalli (Davies), Actinosiphon
tibetica (Douville), Operculina patalensis Davies & Pinfold,
Operculina salsa Davies & Pinfold, Operculina subsalsa
Davies & Pinfold, Assilina dandotica Davies & Pinfold,
Assilina spinosa Davies & Pinfold, Assilina subspinosa
Davies & Pinfold, Assilina laminosa Gill, Assilina granulosa
(d'Archiac), Assilina exponens (Sowerby), Discocyclina ranikotensis
Davies & Pinfold, Discocyclina dispansa (Sowerby), Nummulites
mamillatus (Fichtel & Moll) and some alveolinids. Bioclastic wackestone,
packstone and the grainstone microfacies are developed in these shallow-marine,
shallow shelf deposits. The Paleocene-Eocene can be distinguished by the
appearance of Assilina granulosa (d'Archiac), Discocyclina dispansa
(Sowerby), Nummulites mamillatus (Fichtel & Moll) and the alveolinids.
Miscellanea miscella (d'Archiac & Haime) is mostly found in
Paleocene strata worldwide but its reported occurrence in the Lower Eocene
has been substantiated in southern Pakistan in the Murree-Brewery Gorge
around Quetta.
TOWARD A REVISION OF THE CHRONOSTRATIGRAPHY
OF THE JOHN DAY FORMATION, OREGON
ALBRIGHT, L. Barry, Museum of Northern Arizona, Flagstaff, AZ, USA; Theodore
J. Fremd, John Day Fossil Beds National Monument, Kimberly, OR, USA; Michael
O. Woodburne, University of California, Riverside, CA, USA; Carl C. Swisher,
Rutgers University, Piscataway, NJ, USA; and Bruce J. MacFadden, Florida
Museum of Natural History, Gainesville, FL, USA
Although the Whitneyan, Arikareean, and Hemingfordian
North American Land Mammal "Ages" were first typified in the
Great Plains, the succession there contains significant unconformities,
a generally poor magnetic record, relatively sparse radioisotopic calibration,
and a major faunal hiatus within the Arikareean. In the John Day Valley
of central Oregon, however, is a thick, remarkably complete sequence of
Oligocene-early Miocene strata (the John Day Formation) highly amenable
to addressing these shortcomings and long known to harbor one of the richest
records of mid-Tertiary mammals in North America.
Although Prothero and Rensberger conducted the first
magnetostratigraphic study of the John Day in 1980, new advances in geochronology
call into question the validity of those early results. In our recent
attempt to reinvestigate John Day chronostratigraphic relationships, we
sampled nearly 300 sites for magnetostratigraphy over 500 meters and sampled
several tuffs for 40Ar/39Ar dating. Our preliminary
study indicates that the Turtle Cove Member stratigraphically upward through
the lower Kimberly Member extends from chron C12n to C7n.2n, or from about
30.524.9 Ma. However, the rocks we sampled showed unusual behavior
characteristic of a complex magnetic mineralogy in contrast to rocks in
which the primary remanent magnetization is carried in magnetite whereby
a well defined polarity determination and magnetic direction result. We
also found several intervals of anomalously long normal polarity for this
time period based on our preliminary dating of associated tuffs. Our preliminary
correlation together with the mammal fauna of the lowermost interval suggests
that the Arikareean began nearly 1 m.y. earlier in the Pacific Northwest
than in the Great Plains.
Studies currently in progress are addressing these problems
and will also provide a temporal framework that will allow reappraisal
and refinement of the correlation between the classic mammalian faunas
of the Northern Great Plains and the John Day region.
LATE HOLOCENE RECORDS OF INVERTEBRATE DIVERSITY
AND TURNOVER FROM LAKE TANGANYIKA, EAST AFRICA, AND THEIR CONSERVATION
IMPLICATIONS
ALIN, Simone R., Andrew S. Cohen, and Heather D. Heuser, Dept. of Geosciences,
University of Arizona, Tucson, AZ, USA; and Manuel R. Palacios-Fest, Terra
Nostra Earth Science Research, Tucson, AZ, USA
Lake Tanganyika is a global hotspot of freshwater biodiversity,
with ~2000 described species and high levels of endemism, and is located
in a region with rapid human population growth. Nearshore benthic communities
are the most diverse and the most susceptible to anthropogenic habitat
alteration. Ostracods serve as conservative paleoecological indicators
of change in benthic communities, because they have a higher response
threshold to sediment inundation than fish and molluscs. Ostracods are
preserved in sediment cores in sufficient abundance to allow high-resolution
reconstruction of biodiversity turnover through the recent period of intensive
land-use change in the lake's watersheds.
Using detrended correspondence analyses (DCA) of 14C-
and 210Pb-dated fossil ostracod assemblages, we compared
recent diversity trends in numerous sediment cores collected offshore
from watersheds experiencing various degrees of deforestation. Offshore
from deforested watersheds, sediment accumulation rates increased by a
factor of two- to ten-fold over the last c. 150 years with rate increases
triggered by high rainfall (El Niño) events. Cores near highly
disturbed, large watersheds showed paleoecological trends toward decreasing
species diversity and increasing dominance relative to historical conditions
at the same sites. Intermediate disturbance conditions are often correlated
with slightly higher ostracod diversity in living assemblages than at
undisturbed sites. In cores from moderately disturbed areas, DCA revealed
progressive change in ostracod assemblages through time, although overall
species richness and levels of dominance did not change (often the identity
of dominants did). In cores from undisturbed areas, no major transitions
in the ostracod fauna occurred.
Paleoecological records of microinvertebrate diversity
at sites around Lake Tanganyika suggest that localized recent transitions
in species composition of benthic communities can be ascribed to anthropogenic
alteration of the lake habitat.
SPECIES-LEVEL EVOLUTION OF AMMONOID SUTURE COMPLEXITY:
PASSIVE OR DRIVEN?
ALLEN, Emily G., Committee on Evolutionary Biology, University of Chicago,
Chicago, IL, USA
Recently, many patterns historically interpreted as evolutionary
trends have been re-evaluated to discriminate between two possible underlying
mechanisms: passive diffusion away from morphological bounds or active
directional selection. Yet few studies address how analytical biases,
such as taxonomic window, affect interpretations of these patterns. Here,
I examine some of these issues by contrasting species- and genus-level
analyses of the evolution of ammonoid suture complexity.
Genus-level analysis of the evolution of Paleozoic ammonoids
provides strong evidence for a driven trend toward increased suture complexity
over time (Saunders & Work 1997; Saunders et al. 1999). In contrast,
results from tracking species-level changes in the Prolecanitida, an order
of Paleozoic ammonoids, are more consistent with the passive diffusion
model. Over the 100 m.y. prolecanitid duration, species show a 1400% increase
in mean suture complexity as a consequence of a highly increased variance.
This increase is correlated with the loss of simple-sutured species; however,
there is no steady attrition of less complex forms as was reported for
genera. Instead, average minimum complexity remains constant within families
and there is a stepwise loss associated with the extinction of higher
taxonomic groups. Changes in suture complexity across stratophenetic ancestor-descendent
(A-D) pairs show a minor, non-significant preference for increases (n=87)
over decreases (n=72). Among species, the mean magnitude of increases
(45.5%) is twice that of decreases (21.8%). Large increases in complexity
are associated with the rise of new genera; this observation may help
to resolve the species-level results with the significant bias in genus-level
prolecanitid A-D pairs for increases (n=28) over decreases (n=6). As both
the loss of simple-suture species and the appearance of highly differentiated
forms coincide with the rise of new genera one would expect the trend
to appear driven at higher taxonomic levels, regardless of the species-level
behavior.
TURRITELLID GASTROPODS OF THE NEOGENE OF THE
NORTHERN DOMINICAN REPUBLIC: A ROSETTA STONE FOR THE MID-LATE CENOZOIC
WESTERN ATLANTIC HISTORY OF THE GROUP?
ALLMON, Warren D., Paleontological Research Institution, Ithaca, NY,
USA
Gastropods of the family Turritellidae are rare overall
in Neogene sediments of the northern Dominican Republic, although they
are occasionally locally abundant. They are also relatively un-diverse,
with only three species having previously been recognized: Turritella
planigyrata Guppy 1867, T. tornata Guppy 1866, and T. submortoni
Maury 1917 (which may be synonymous with planigyrata). ("Turritella"
is used here sensu lato.) Yet the occurrence of the group in these
well-sampled exposures may provide important information about its biogeographic,
phylogenetic, and paleoenvironmental history. T. tornata appears
to belong to a clade that includes T. rina Palmer 1937 and its
relatives from the Eocene and Paleocene of the US Gulf Coastal Plain,
as well as several taxa in the later Neogene of Florida and elsewhere,
including the abundant T. perattenuata Heilprin 1887 and the Recent
T. exoleta Linnaeus 1758. T. planigyrata may belong to a
clade that includes T. mortoni Conrad 1830 from the Paleocene of
the Gulf Coast and its Paleogene relatives. Its later relatives remain
unknown. Preliminary analysis of the paleoenvironmental distribution of
turritellids in the Domincan sequence suggests that it may document part
of the transition from a more thermophilic pattern that characterized
the group earlier in its history to a more frigiphilic and nutriphilic
habit that characterizes and controls its distribution later.
THE PALEOBIOLOGY DATABASE
ALROY, John, NCEAS, University of California, Santa Barbara, CA, USA
The Paleobiology Database is a five-year, NSF-funded
initiative to build an open, World Wide Web-based resource for the paleontological
community. The Database currently includes 50 Ph.D.s and 19 students from
33 institutions; any professional researcher who wants to contribute data
may join. Researchers enter, edit, and analyze data over the Web.
We also plan to develop Web-based data sharing protocols
with other databases. The Paleobiology Database originated in the Phanerozoic
marine paleofaunal diversity project (19982000), which was funded
by the National Center for Ecological Analysis and Synthesis (NCEAS).
This initiative, which seeks to produce a sampling-standardized Phanerozoic
diversity curve using rigorous statistical techniques, continues as the
Paleobiology Database marine working group. It has so far compiled data
on 10,076 Neoproterozoic-Paleogene fossil collections that are made up
118,821 taxonomic occurrences, mostly from North America and Europe. Three
new working groups for paleobotany (discussed later in the symposium),
vertebrates, and taphonomy have been established. The vertebrate group's
initial goal is to quantify large-scale sampling intensity patterns by
databasing a randomly drawn subsample of the literature. The group also
will bring together existing data sets: the North American Mammalian Paleofaunal
and Fossil Mammal Systematics Databases; a global data set on dinosaurian
taxonomy, phylogeny, and body size; detailed occurrence data on Karoo
vertebrates; and additional data on both terrestrial and marine Mesozoic
and Cenozoic vertebrates. The taphonomy group bridges the others and seeks
to quantify large-scale taphonomic patterns in the record. All four groups
meet periodically at NCEAS. Preliminary results concerning three research
areas will be discussed: removing the effects of sampling intensity bias
from estimates of diversity using occurrence data; analyzing abundance
distributions using specimen count data; and modelling the dynamics of
evolutionary trends using phylogenetic and morphometric data.
ENVIRONMENTALLY ASSOCIATED ALLOMETRY AND SIZE
TRUNCATION IN NEOGENE CARYOCORBULA OF THE NORTHERN DOMINICAN REPUBLIC
ANDERSON, Laurie C., Dept. of Geology and Geophysics, Louisiana State
University, Baton Rouge, LA, USA; and Peter D. Roopnarine, Dept. of Invertebrate
Zoology and Geology, California Academy of Sciences, San Francisco, CA,
USA
Richly fossiliferous Neogene deposits of the northern
Dominican Republic have been a source of taxa for numerous evolutionary
studies over the last two decades. A reexamination of Dominican Caryocorbula
from this area using landmark-based techniques, relative warp analysis
and canonical variates analysis reveals better separation among morphologies
than is achieved with traditional measures and principle components analysis.
At least three species can be recognized. As is common in Neogene Caryocorbula
of tropical America, a strong allometric trend is apparent among species.
Because species distributions are strongly facies dependent, this allometric
trend is correlated with an environmental gradient. Larger, elongate Caryocorbula
occur in marginal- to very shallow-marine deposits (<30 m). Intermediate-sized
subtriangular Caryocorbula occur in sediments deposited in shallow-water
(also <30 m) with a fully marine salinity. The smallest Caryocorbula,
which are triangular, are found in sediments deposited in water of intermediate
depth (30100 m). Caryocorbula in deeper-water deposits (>100
m), however, are the same shape as, but are larger than, those found in
intermediate depths.
These Dominican sections one of the few molluscan-rich
shallow-marine units of Messinian and Zanchlean age that are well documented
in tropical America. In these uppermost Miocene to lower Pliocene sediments,
the earliest evidence of a dramatic size decrease in Caribbean Caryocorbula
is recorded. This size minimum does not appear to be facies related or
taphonomicaly based. The size minimum does not appear to have affected
all corbulids, however, and large-bodied Bothrocorbula are locally
abundant in the upper Miocene Cercado Formation. The size decrease in
Caryocorbula appears to be triggered by a productivity collapse
associated with emergence of the Isthmus of Panama that also warmed the
Caribbean and made it more carbonate rich.
RESURRECTION OF AN OLD WORLD FOSSIL, THE ECHINOID,
MELONECHINUS MULTIPORUS
ANGELI, Nicholas, Patricia Eicks, and Bruce L. Stinchcomb, Dept. of Geology,
St. Louis Community College at Florissant Valley, St. Louis, MO, USA
Some historically significant, paleontological wonders
once described in the rudimentary firsts of documented literature often
remain silent, throwing up no barriers of questionable origin, affiliations
or misinterpretations. They remain dormant and undaunted as the world
of paleontology grew up around them, leaving only a trail of unparalleled
enchantment for us to follow.
Melonechinus Meek and Worthen 1860 (Melonites
Norwood and Owen 1846) is one such fossil. Described by J.G. Norwood and
D.D. Owen through the Transactions of the Saint Louis Academy of Science
after a visit to Saint Louis in the winter of 18441845. Three specimens
were recovered from near low water mark along the Mississippi River from
the Limestone Formation of what is presently known as the St. Louis Formation,
Mississippian or Lower Carboniferous Period. Additional discoveries were
later made in the old north city sections. These yielded specimens of
the cantaloupe-shaped echinoid made famous by their discovery as a biostrome
in a quarry. Workman noted their unusual shape and commonly referred to
them as coltsfoot in reference to the resemblance of the frog of a horse's
foot.
Minor taxonomy problems were worked out by paleontologists
such as Agassiz, McCoy, Jackson, Jaggar, Keys, and of course Meek and
Worthen. These Victorian paleontological dilemmas started at the class
level and included the inclusion of echinoids with the Crinoidea. Early
thinking suggested that echinoids were attached by a pedicel stalk or
jointed columns, simply because some washed in crinoid stems were consolidated
with the specimens. Almost all other systematical descriptions had to
do with the number and arrangement of ambulacral plates and pores. Later
works solved problems at the species level eventually settling at fourteen
species by 1910.
In 1860 Meek and Worthen renamed the genus Melonechinus
from Melonites to which Lamarck first applied the name (Melonites)
for the genus Polypi (an anthozoa) thus retaining the name if so
needed.
PHYLOGENETIC AND BIOGEOGRAPHIC IMPLICATIONS
OF PERMIAN DICYNODONTS FROM RUSSIA
ANGIELCZYK, Kenneth D., Dept. of Integrative Biology and Museum of Paleontology,
University of California, Berkeley, CA, USA
Anomodont therapsids have been known from Russia since
the first half of the 20th century. Most research on these forms traditionally
focused on Permian basal anomodonts such as Otsheria, Ulemica,
and Venyukovia or derived Triassic dicynodonts similar to Kannemeyeria.
However, several recently described Permian dicynodonts show clear differences
from their Gondwanan contemporaries, indicating that Eastern Europe may
have been an area of considerable endemism for dicynodonts.
To examine the relationships of the Russian dicynodonts,
a cladistic data matrix was constructed of six Russian taxa and 18 genera
known predominantly from South Africa. Forty-six morphological characters
were coded and Patranomodon and Otsheria were used as outgroups
to root the most parsimonious cladograms. The results of this analysis
suggest that the Russian taxa Elph and Interpresosaurus
form a clade that is the basal sister of the clade including taxa such
as Dicynodon, Kannemeyeria, Oudenodon , and Aulacephalodon.
Also, Dicynodon, Lystrosaurus, and Kannemeyeria nest
within a clade including the Russian taxa "Dicynodon"
trautscholdi, Delectosaurus, and Vivaxosaurus. Vivaxosaurus
is reconstructed as the sister group of Kannemeyeria.
These results are interesting because they are compatible with a Russian
origin of many South African dicynodont genera. However, at the current
level of taxon sampling, it is equally parsimonious to posit dispersal
into Eastern Europe by South African taxa. Stratigraphic information could
help resolve this uncertainty, but correlations between Russia and South
Africa are poor. Further phylogenetic and stratigraphic studies will be
necessary to test the hypotheses presented here, but these results emphasize
that the South African fossil record does not preserve the full history
of dicynodont evolution in the Late Permian.
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