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Terraces through time: Reconstructing fossil beaches in southern California

San Nicolas Island is a strange, far-away place very familiar to a surprising number of Californians. Thanks to Scott O'Dell's Island of the Blue Dolphins, this island — the most remote of California's eight Channel Islands — and it's native Nicoleño people have been engrained into the imaginations of many elementary school children. My own mind was captivated by this story in the fourth grade when I had the opportunity to conduct fieldwork on San Nicolas Island with Daniel Muhs (U.S. Geological Survey) and my adviser Seth Finnegan in July 2015 I was thrilled! Descending from hundreds of feet above the island’s landing strip I was already able to spot the very reason for my fieldwork- Pleistocene fossil beaches.

san-nicolas-ile

San Nicolas Island from above showing its terraced coastline. Marine terraces - records of ancient beaches - are formed by the powerful erosional energy of waves. They are relatively flattened geomorphological features that can serve as convenient pre-leveled platforms for human infrastructure. Hence, San Nicolas Island’s naval base airstrip (the island has been a naval base since the 1940’s) lies atop the island’s seventh terrace, which is the island’s most apparent marine terrace. Photo by D. Günther

Emily standing on a concretion jutting out just below San Nicolas Island’s youngest marine terrace (~80,000 years old).

Emily standing on a concretion jutting out just below San Nicolas Island’s youngest marine terrace (~80,000 years old). Photo by Seth Finnegan

Carved by the powerful energy of ancient waves, over 11 Pleistocene fossil beaches are terraced (hence their geological name "marine terrace") over the landscape of San Nicolas Island's modest 23 square miles. The youngest fossil beach (~80,000 years old) sits just above present-day sea level and the oldest (~1,200,000 years old) lies atop the island's highest elevation. Fossil mollusc shells — very similar to the kinds you find along California beaches today — abound within these marine terraces. Differences in the species compositions and abundance of these mollusc shells record dynamic ecological changes that occurred in response to glacial-interglacial climatic change during the Pleistocene.

Close-up of marine terrace sediments from one of the island’s oldest marine terraces (~1,200,000 years old). Fossil preservation on this terrace is exceptionally good- with original shell color preserved on many specimens.

Close-up of marine terrace sediments from one of the island’s oldest marine terraces (~1,200,000 years old). Fossil preservation on this terrace is exceptionally good- with original shell color preserved on many specimens.

My goal on San Nicolas Island is to collect fossil shells from the lowest three marine terraces — which record the last full interglacial cycle (~120,000 – 80,000 years ago). In particular, I am collecting well-preserved fossil Callianax biplicata (common name, purple olive shell) specimens. Using these fossil shells, I am reconstructing paleoenvironmental conditions during the last interglacial period through the use of stable isotopes. The reason this is possible is because shells grow by semi-continuously depositing layers of calcium carbonate. In the same way scientists use tree rings to chronicle the life a tree, I am using shell growth layers to reconstruct the environmental conditions experienced during the lives of molluscs that lived during the last interglacial period.

After collecting fossil C. biplicata from the terraces of San Nicolas Island, Sydney Minges (UCB Integrative Biology and Earth Planetary Sciences undergraduate student) and I sampled tiny holes along shell growth lines and analyzed these samples for carbon and oxygen stable isotope ratios at UC Berkeley's Center for Stable Isotope Biogeochemistry. Taken together, these isotope ratios can be used to reconstruct changes in seasonal, annual, and inter-annual seawater conditions and temperature during the last interglacial period. When combined with paleoecological species abundance and composition data, these paleoenvironmental data will allow me to test whether species lived in environmental regimes during the last interglacial period that are quite different from conditions they experience today, or whether species have tracked their environmental niches from the last interglacial period to the present day.

emily-collage

Left: Emily sampling fossil C. biplicata (purple olive shell) from a terrace on San Nicolas Island; the majority of white shells in photo are C. biplicata specimens. Photo by Seth Finnegan. Top Right: C. biplicata modern shell (specimen in ~1 cm in length). C. biplicata are the most abundant shells on both modern and Pleistocene beaches in southern California. Bottom Right: Sectioned fossil C. biplicata shell; small holes along right side of shell are spots that are being sampled for stable isotope analysis. Photo by Sydney Minges.

San Nicolas Island is only one of my dissertation study areas. Ultimately, I hope to reconstruct the paleoenvironmental and paleoecological conditions of the last interglacial period along much of the coast of southern California. The uniqueness of this Channel Island's geology and biota will leave a lasting impression. Aside from its extensive marine terraces and rich archaeological record, San Nicolas Island also boasts ghostly caliche forests, adorable dwarfed gray foxes called "island foxes", and some of the most pristine rocky intertidal habitats in southern California. Through my work reconstructing the paleoenvironmental and paleoecological characteristics on San Nicolas Island and elsewhere in southern California, I hope to establish a pre-human baseline for how shallow marine environments respond to climate change.

Emily and Dan Muhs on a marine terrace with abundant Giant Coreopsis plants. Photo by Seth Finnegan.

Emily and Dan Muhs on a marine terrace with abundant Giant Coreopsis plants. Photo by Seth Finnegan.

Island fox on San Nicolas Island. Island foxes are dwarfed relatives of mainland California’s gray fox. Adult island foxes weigh about 4 pounds. Photo curtesy of the Island Conservancy.

Island fox on San Nicolas Island. Island foxes are dwarfed relatives of mainland California’s gray fox. Adult island foxes weigh about 4 pounds. Photo curtesy of the Island Conservancy.

Caliche forest that dates to the Last Glacial Maximum; fossil root casts- many of which are Giant Coreopsis- are visible. Caliche is a sedimentary rock made of calcium carbonate cement. Photo by Emily Orzechowski.

Caliche forest that dates to the Last Glacial Maximum; fossil root casts- many of which are Giant Coreopsis- are visible. Caliche is a sedimentary rock made of calcium carbonate cement. Photo by Emily Orzechowski.

Intertidal sea urchins living in holes bored into Eocene sandstone on San Nicolas Island.

Intertidal sea urchins living in holes bored into Eocene sandstone on San Nicolas Island.

This work is generously supported by grants from The UC Museum of Paleontology, National Sigma Xi, Berkeley Chapter of Sigma Xi, The UC Berkeley Department of Integrative Biology, The Evolving Earth Foundation, The American Philosophical Association, the American Association of Petroleum Geologists, the American Museum of Natural History, and the Geological Society of America.

Our journey from the UCMP to South Africa to study fossil monkeys

Mrs. Charles Camp and her son, Charles Camp Jr., in South Africa (1947-48). Photo by Tesla Monson

Mrs. Charles Camp and her son, Charles Camp Jr., in South Africa (1947-48).

At the time we got involved in what has now become for us - the South Africa project - one of us (Tesla) was soon-to-be a second year graduate student, and the other (Marianne) was about to start her senior year as an undergraduate student here at UC Berkeley.

We began working together in the UC Museum of Paleontology (UCMP) during the summer of 2013, making our way through a massive project and cataloguing exceptional fossil material collected during the UC Africa Expedition of 1947 and 1948. This is the story of that project and the journey that followed.

The UC Africa Expedition

A bit of background for those who may not be familiar with this aspect of UC Berkeley history… as World War II ended, a massive research expedition, dubbed The UC Africa Expedition (UCAE) was just beginning to pick up steam on Berkeley campus. From 1947-1948, the extensive research endeavor became an influential force across numerous fields of study.

During this time, the Expedition also attracted plenty of media attention, resulting in dozens of newspaper articles that were published while the expedition was underway. There were two separate branches of the expedition: the northern branch (led by Wendell Phillips) and the southern branch (led by our very own Charles Camp, director of the UCMP from 1930-49). In addition to all of the fossil material that is now housed in the UCMP, the UCAE brought back an enormous amount of material that, to this day, spans a wide range of libraries, museums, and other repositories on the UC Berkeley campus.

The list below gives you an idea of the amount and diversity of non-fossil materials collected by the expedition and stored outside of the UCMP:

  • The Museum of Vertebrate Zoology has many mammal specimens that were collected during the UCAE by Thomas Larson, ranging in size from bats and elephant shrews to large antelopes.
  • The Phoebe A. Hearst Museum of Anthropology has large amounts of archaeological and ethnographic material, ranging from stone tools to stools, many of which come from the Ovambo people in South Africa. Faunal and archaeological materials collected at the Middle and Late Stone age excavation sites are also stored at Hearst.
  • The Music Library has a series of recordings of local traditional music from South Africa, recorded by famed ethnomusicologists Laura Boulton and Hugh Tracey.
  • The Bancroft Library holds many photographs documenting the life of Charles Camp and his family during the expedition. The library also has many photos of local people and their traditions, as well as the landscapes on which they lived.
  • The UC Botanical Gardens received seeds and living plants that were collected by Robert Rodin, and some of those living plants perpetuate and can still be visited in the African section of the garden.
  • The University and Jepson Herbaria also have a considerable number of specimens, as well as Robert Rodin’s field notes and correspondences. A complete list of everything collected can be found in his preserved field notes.
Fossil primates at the Evolutionary Studies Institute in Johannesburg, South Africa. Photo by Tesla Monson

Fossil primates at the Evolutionary Studies Institute in Johannesburg, South Africa. Photo by Tesla Monson

Following our curatorial and historical work with this collection, we narrowed our focus to the Plio-Pleistocene fossil assemblage. For a more extensive historical account of the UCAE, and faunal and locality details for the Plio-Pleistocene fossil assemblage, see our recently published paper in PaleoBios (Monson TA et al. 2015).

As we turned our attention to the Plio-Pleistocene assemblage, two undergraduate students who were involved in the curatorial process took on independent projects. Sandy Gutierrez examined the ostrich eggshells and quantified interspecific variation in shell characteristics. And Bogart Marquez, emphasizing the bovids, studied the faunal composition of the different caves in order to make inferences about deposition, taphonomy, and predatory behavior in and around the caves. Both Sandy and Bogart presented their results at the Society for the Advancement of Chicanos and Native Americans in Science (SACNAS) conference in Spring 2014.

We also dug into the primate material with the goal of assessing the alpha-taxonomy of the UCMP specimens. This part of the assemblage includes specimens that have been very influential throughout the historical course of monkey taxonomy, and many are still quite controversial. We tag-teamed the project, with Marianne working through the mandibular material as part of her honors thesis and Tesla examining the cranial material. Two then-undergraduates in the Hlusko Lab also worked with the primate material: Kevin Roth examined the juvenile craniodental specimens and Sandy Gutierrez looked at the postcranial material.

Tesla poses for a selfie with Sediba, a South African australopithecine.

Tesla poses for a selfie with Sediba, a South African australopithecine.

The whole group (Tesla, Marianne, Sandy, Bogart, and Kevin) presented our results during a UCMP Fossil Coffee seminar back in Spring 2014 and at the American Association of Physical Anthropologist (AAPA) meeting in April 2014. Fortuitously, our Fossil Coffee presentation was attended by Dominic Stratford, a visiting South African geoarchaeologist from University of the Witwatersrand in Johannesburg, South Africa. Dominic has become an invaluable collaborator on the multiple monkey projects that evolved out of our initial work in the UCMP and that are still ongoing. These projects led us (and our advisor – Leslea Hlusko) on the next leg of our journey. In summer of 2015, we journeyed to South Africa to collect more monkey data, a trip graciously funded by a grant from the Palaeontological Scientific Trust and two Desmond C. Clark fellowships from the Human Evolution Research Center at UC Berkeley.

South Africa

Data Collection

hominid-vault

The entrance to the hominid vault at the Evolutionary Studies Institute in Johannesburg, South Africa. Photo by Tesla Monson

During our time in South Africa, we studied monkey cranial and dental specimens at University of the Witwatersrand in Johannesburg and at the Ditsong Museum of Natural History in Pretoria. While it was an incredible experience and opportunity, we couldn’t help but feel like some of the days stretched on forever - we were in the museum for nine hours at a time, and some days it felt like all we had to eat was chicken, chicken, and more chicken.... which, according to Dominic, actually qualifies as a vegetable in South Africa. Tesla had to tape her thumbs, followed by her index fingers, followed by almost every other finger, to prevent caliper burn, and Marianne had to squint out of one eye for two weeks straight. (But we made sure to take semi-frequent jellybean breaks to preserve our sanity, thanks Leslea!) It may not have felt like it while we were squinting at calipers and working through the burn, but the amount of data collected made the long hours very worthwhile. Not to mention that we were in good company while at University of the Witwatersrand, since original South African hominid fossil material, including the Taung child, Malapa and Sediba, were displayed (complete with spotlights!) in the vault where we were working.  Yes, that’s correct – a vault. We were stationed in the Hominid Vault at the Evolutionary Studies Institute, a very serious room fully equipped with a 6-foot vault door with rotating handle, locked by a 4-inch key that looked a hundred years old. Serious business indeed.

When we weren’t measuring and photographing monkeys, we got to take tours of some of the famous cave sites, and wow were they incredible! We also got to meet paleoanthropologist Ron Clarke and see the “Little Foot” hominid remains, which are still in the process of being prepared – an opportunity that has only been offered to only a handful of people in the world. Hey, it pays to be a paleontologist!

The surface layers at Sterkfontein Cave in the Cradle of Humankind, South Africa.

The surface layers at Sterkfontein Cave in the Cradle of Humankind, South Africa.

Marianne Brasil, Leslea Hlusko and Dominic Stratford underground in Sterkfontein Cave, South Africa. Photo by Tesla Monson

Marianne Brasil, Leslea Hlusko and Dominic Stratford underground in Sterkfontein Cave, South Africa. Photo by Tesla Monson

Marianne Brasil and Tesla Monson in Sterkfontein Cave. Photo by Leslea Hlusko.

Marianne Brasil and Tesla Monson in Sterkfontein Cave. Photo by Leslea Hlusko.

Famed anthropologist Ron Clarke holding the cranium of “Littlefoot,” a recently discovered South African hominid. Photo by Tesla Monson

Famed anthropologist Ron Clarke holding the cranium of “Littlefoot,” a recently discovered South African hominid.

In the evenings while we were in Pretoria, we ate our delivery dinners (mostly chicken) on the floor of Leslea’s room, and sometimes it was in candlelight because of this odd, but normal “it’s just a part of life here,” load-shedding phenomenon that causes small-scale city blackouts. This was only one of the quirks of South Africa that we encountered. Some others included…

  1. No picture on a restaurant menu was ever actually replicated in person. Dishes served were a surprise every time!
  2. The GPS had a fondness for telling us to “Turn left at unknown road”, as if that’s helpful.
  3. On more than one occasion we had to let baby goats get out of the road before we could continue on our way. Ok, that last one wasn’t so bad… 🙂

Exploring Africa

Following all of the hard work of data collection, we finally got to explore South Africa. We set off - with Tesla driving on the wrong side of the road, in the wrong side of the car, and with the clutch on the left – to our rental at “Zonk Lake”, which was a lone cottage on a tiny lake. So, we basically rented a lake. It’s not often you get to take a romantic vacation with your labmate…

Giant’s Castle reserve in the Drakensberg. Photo by Tesla Monson

Giant’s Castle reserve in the Drakensberg. Photo by Tesla Monson

During the couple of days that we were in the Drakensberg region, we went out to enjoy the natural beauty of the landscape as well as the San petroglyphs of Giant’s Castle. We were also able to see our study organisms in their (not so) natural habitat when we ran into chacma baboons in a park area while out for a hike. On a more serious note, it was an honor and a privilege to tour the Apartheid Museum and the Nelson Mandela Memorial while we were in KwaZulu-Natal, and we highly recommend it to any visitors in the area.

San petroglyphs on the rocks at Giant’s Castle, South Africa. Photo by Tesla Monson

San petroglyphs on the rocks at Giant’s Castle, South Africa. Photo by Tesla Monson

Chacma baboons (Papio hamadryas) eating grass at the Giant’s Castle resort in the Drakensberg. Photo by Tesla Monson

Chacma baboons (Papio hamadryas) eating grass at the Giant’s Castle resort in the Drakensberg. Photo by Tesla Monson

A panel from the Apartheid Museum at the Mandela Capture Site near Howick in KwaZulu-Natal. Photo by Tesla Monson

A panel from the Apartheid Museum at the Mandela Capture Site near Howick in KwaZulu-Natal. Photo by Tesla Monson

Taking the kayak out on Zonk Lake. Photo by Tesla Monson

Taking the kayak out on Zonk Lake. Photo by Tesla Monson

Marianne practices the art of braai, South African barbeque. Photo by Tesla Monson

Marianne practices the art of braai, South African barbeque. Photo by Tesla Monson

During the evenings, we caught Marianne up on the childhood media she never had, pulling from the random assortment of VHS cassettes that someone left on the shelf of our Zonk cabin: Casper, Mask of Zorro, Daredevil – all the greats. We also went kayaking in the early morning, and had true South African “braai” (AKA barbeque) in the evenings. You know what they say — when in South Africa...

After Zonk Lake, we left early for the nine-hour drive to Kruger National Park. Luckily, awesome street signs and plenty of bad jokes from Tesla dotted our journey. When we finally made it to Kruger, we quickly loaded up on snacks, brewed our coffee at 5:30 in the morning, and set out to drive through the park. The first thing we saw was a rhino (spotted by Tesla). We had heard that some people never see anything, so the mood was gleeful right way.

Then, maybe 20 meters down the road past the rhino, we saw an elephant (spotted by Marianne). The day just got better after that. We saw giraffes, lions, hippo, impala, hyena, kudu, crocodiles, warthogs, TONS of birds, baboons, buffalo, zebra, mongoose, and many other cool critters – including loads and loads of baby animals. Oh the babies!

A white rhinoceros (Ceratotherium simum) in Kruger National Park, South Africa. Photo by Tesla Monson

A white rhinoceros (Ceratotherium simum) in Kruger National Park, South Africa. Photo by Tesla Monson

Southern ground hornbills (Bucorvus leadbeateri) in Kruger National Park, South Africa. Photo by Tesla Monson

Southern ground hornbills (Bucorvus leadbeateri) in Kruger National Park, South Africa. Photo by Tesla Monson

Giraffes (Giraffa camelopardalis), impala (Aepyceros melampus) and warthogs (Phacochoerus africanus) at a watering hole in Kruger National Park, South Africa. Photo by Tesla Monson

Giraffes, impala and warthogs at a watering hole in Kruger National Park, South Africa.

An African elephant (Loxodonta africana) in Kruger National Park, South Africa. Photo by Tesla Monson

An African elephant (Loxodonta africana) in Kruger National Park, South Africa. Photo by Tesla Monson

A baby spotted hyaena cub (Crocuta crocuta) in Kruger National Park, South Africa. Photo by Tesla Monson

A baby spotted hyaena cub in Kruger National Park, South Africa. Photo by Tesla Monson

A zebra (Equus burchelli) in Kruger National Park, South Africa. Photo by Tesla Monson

A zebra in Kruger National Park, South Africa. Photo by Tesla Monson

A warthog (Phacochoerus africanus), also known as “Radio Africa,” runs with its tail up. Photo by Tesla Monson

A warthog  also known as “Radio Africa,” runs with its tail up. Photo by Tesla Monson

A vervet monkey (Chlorocebus pygerythrus) hangs out near a rest area in Kruger Park, South Africa. Photo by Tesla Monson

A vervet monkey hangs out near a rest area in Kruger Park, South Africa. Photo by Tesla Monson

Overall, our trip was really productive, and we had a really excellent time. We collected lots of data, generated many hypotheses we’re currently testing, and raised questions that we are working to answer. We will both be presenting at the AAPA meeting in April 2016 on some of our findings from the data collected on this trip. We also got to know each other really, really well and we’re both happy to say, we’d go on another data collection trip to Africa together anytime!

The sun sets over Kruger National Park, South Africa. Photo by Tesla Monson

The sun sets over Kruger National Park, South Africa. Photo by Tesla Monson

A first: Sauropod bones found in Ethiopia!

Assistant Director Mark Goodwin and his project collaborators (see Feb. 1 blog post) made a surprising discovery while collecting microvertebrates, turtles, and fish.  Within a small area of exposure in the Late Jurassic Agula Shale in the Tigray Province, just south of Mekele, Ethiopia, were the first sauropod dinosaurs ever reported from Ethiopia!

The team found mostly partial bones and bone fragments, and the local school kids delighted in holding Ethiopia's first sauropod dinosaur bones.

Mark labeling some of the bones with Connie Rasmussen (Univ. of Utah) and local school kids looking on.

Mark labeling some of the bones with Conny Rasmussen (Univ. of Utah) and local school kids looking on.

Million Alameyeho & Samuel Getachew (Addis Ababa U.) and Tadesse Berhanu (Oklahoma State U,) with local school kids

Million Alameyeho & Samuel Getachew (Addis Ababa U.) and Tadesse Berhanu (Oklahoma State U,) with local school kids

sauropod bones

Close up of some of the many sauropod bones found by the field party.

Assistant director reunites with UCMP alumni in Ethiopia to investigate Mesozoic ecosystems

Assistant director Mark Goodwin is in Ethiopia for several weeks as part of a collaborative project with UCMP alums Greg Wilson (University of Washington) and Randall Irmis (Utah). Together with colleagues from the University of Oklahoma, Addis Ababa University, and Mekelle University in Ethiopia, the team is investigating non-marine Mesozoic ecosystems from the Northwestern Plateau, Ethiopia.

Mark reports "we had great success in the Late Jurassic units and it is gratifying working with Ethiopian students and staff from the Earth Sciences Dept at Addis Ababa University. In the late Jurassic Mugher Mudstone, in addition to turtles, fish, croc teeth and verts, we found a partial crocodile skull with brain case and parietals, partial lower jaw, many allosauroid-like theropod teeth at almost every site and finally some large dinosaur bones - still fragmentary but we're getting there - and very rich micro vertebrate localities that just have to have mammals - collected some bags of sediment from each. Working with the Earth Sciences Dept at Addis Ababa University has been great and hopefully a model for future work and lots of opportunity for collaboration, including informal science."

This collaborative research project, "US-Ethiopia planning visit for the investigation of non-marine Mesozoic ecosystems from the Northwestern Plateau, Ethiopia," is funded by the National Science Foundation grant NSF-CNIC-1444238.

Group pic at the top of the flood basalts that cap the steep sided canyons of the Blue Nile Gorge, near Fiche, Ethiopia. From L to R: Tadesse Berhanu (PhD student, Oklahoma State); Connie Rasmussin (PhD student, Utah); Keegan Melstrom, PhD student, Utah); Randy Irmis (Utah); Greg Wilson (Washington); Mark Goodwin (UCMP); Dave Demar (Postdoc, Washington); Million Mengesha and Samuel (Earth Sciences Dept., Addis Ababa University).

Group pic at the top of the flood basalts that cap the steep sided canyons of the Blue Nile Gorge, near Fiche, Ethiopia. From L to R: Tadesse Berhanu (PhD student, Oklahoma State); Conny Rasmussin (PhD student, Utah); Keegan Melstrom, PhD student, Utah); Randy Irmis (Utah); Greg Wilson (Washington); Mark Goodwin (UCMP); Dave Demar (Postdoc, Washington); Samuel Getachew and Million Mengesha  (Earth Sciences Dept., Addis Ababa University).

National Fossil Day website features research by UCMP and partners

The UCMP partnership with Point Reyes National Seashore and the National Park Service continues to thrive and fossil discoveries made as a result of this partnership are highlighted in a previous post. Lillian Pearson, who works part-time with Museum Scientist Erica Clites cataloging specimens from the Point Reyes National Seashore, is the lead author on an article posted in honor of National Fossil Day (October 14, 2015) describing Cenozoic life and landscape features.

National Fossil Day article summarizes the research here.

12_PORE_NPS_01

Robert Boessenecker (College of Charleston), Lillian Kennedy Pearson (GeoCorps Intern at Point Reyes National Seashore), Sarah Boessenecker, and Erica Clites (University of California, Musuem of Paleontology), are excavating the partial skeleton of an extinct porpoise. The skeleton was excavated from the Purisima Formation on Drakes Beach and includes a nearly complete skull, ribs, several vertebrae, and a humerus. Photo by Kathleen Zoehfeld.

Building a forest: The adventures continue in the Jose Creek Member

It's April 18, 2015, and I am sitting in a room at the Charles Motel in Truth or Consequences, New Mexico, the same apartment-style room that I have stayed in during the past four years of field work. Time sure has passed by quickly; from my first paleontological dig as an undergraduate at Texas State University-San Marcos under Dr. Gary Upchurch, to my ambitious inaugural self-guided field trip as a first-year graduate student at Berkeley, to last year's even longer field excursion, and finally to this short trip with my advisor, Cindy Looy. What keeps bringing me back to this area is an exceptional Late Cretaceous flora in the Jose Creek Member of the McRae Formation—this flora is the foundation of my dissertation work.

I am interested in the functional diversity (the range of plant ecological strategies) of Cretaceous forests in warm-wet climates. Cretaceous floras often contain a mix of plants that are no longer seen in association today. The Jose Creek assemblage, for example, includes both palms and redwoods. These non-analog communities can be difficult to understand from the perspective of community ecology, because we cannot make inferences about their ecology based on similarities in taxonomic composition with modern floras. The difficulty of understanding past communities is compounded by the paucity of fossil deposits preserving a "snapshot" of a forest in relative growth position. This is precisely why the Jose Creek deposit is so unique—it contains a flora preserved in a volcanic ash airfall. During my 2013 field season, we traced a single-horizon ash layer for approximately 1.2 km (see previous blog). Such an extensive deposit makes reconstruction of the forest, including lateral variation in forest structure, possible. Because the volcanic ashes are fine-grained and deposited rapidly, the plant parts (leaves, fruits, flowers, seeds, cones, etc.) are very well preserved. I am using morphological features of these plant fossils—and an explicit ecological and spatial sampling scheme—to reconstruct the forest. My ultimate goal is to evaluate the ecological diversity of the community, and to understand how forests in warm-wet climates have changed since the Late Cretaceous.

Leaf specimens and Dori

Assorted leaf specimens found at the Jose Creek site, and Dori, happy to have found a cone attached to conifer foliage. Leaf photos by Dori Contreras; photo of Dori by Stephanie Ranks.

This is what brings me to Truth or Consequences this April—a continuation of my quest to describe this incredible flora. This trip is a short one—only four days—with two simple missions: (1) "cherry picking" well-preserved leaf specimens to use for trait measurements (for inferences of their ecology), and (2) hunting for cones to finish a whole-plant description of an extinct redwood that is abundant in the deposit.

Last June's trip (2014) was more intensive. I drove to New Mexico with two undergraduates—James Buckel and Negin Sarami—and recent IB graduate/Looy Lab veteran, Stephanie Ranks. We spent two weeks working at the site, establishing new collecting quarries and re-sampling the 12 small exploratory quarries from the previous year, effectively doubling their size. All in all, we have now established 17 quarries that span the length of the exposure! We successfully employed a new data collection method in the field, which had several advantages over the previous year. During the 2013 collecting trip, we collected and brought back to the UCMP all of the specimens excavated from each quarry. This generated a large amount of material very quickly—the maximum that our extra-long SUV could carry. In contrast, during the 2014 trip we looked at all our excavated specimens, comparing them with a leaf morphotype guidebook of over 120 different leaf types that I created from the previous collections. Using the book as a guide, we were able to record the number of occurrences of each morphotype, as well as their percent cover of the rock surfaces, without having to bring every specimen back to the museum. Of course, we did collect the specimens that were very well-preserved or that represented new morphotypes. By adopting this method in the field, we were able to collect far more data than would have been possible by only making collections and still bring back a full load of really nice specimens to the museum.

Negin wrapping and labeling

Negin wrapping and labeling fossils to take back to UCMP. Photo by Dori Contreras.

Dori, Stephanie, and James

The field crew: Dori, Stephanie, and James (Negin not pictured). Photo by CJ at the Charles Motel and Hot Springs.

The flora has proven to be extremely diverse, with new morphotypes being found every day. The variation in morphotype composition from quarry to quarry also suggests a very structurally diverse flora. This is an incredible site to work, never a dull moment! I am really looking forward to the next big trip, and consider myself extremely lucky to receive the support of so many organizations, especially the UCMP and its amazing community of researchers, staff, and donors. Now, back to the field site before I lose any more daylight—Cindy and I still have a day of "wow" moments ahead of us before we return to Berkeley!

Organizations that have generously supported this work include:
— UCMP Graduate Student Award, University of California Museum of Paleontology, 2013 and 2014
— Geological Society of America Graduate Student Research Grant, 2014
— Integrative Biology Graduate Research Fund, 2014
— Sigma Xi Grants-in-Aid of Research, UC-Berkeley Chapter, 2014
— Mid-American Paleontological Society (MAPS) Outstanding Student Research Award, 2013
— GRAC Research Funds, UC-Berkeley Integrative Biology Department, 2013

Do green tide algae reproduce all year?

Occurrences of green tides have been on the rise in recent years worldwide. The most impressive have been reported off the coast of China in the Yellow Sea. In August 2014, the Monterey Bay area experienced a green tide that resulted in the accumulation of the macroalgae, Ulva, on its beaches. Algal blooms often make the headlines in spring and summer yet they are not a new phenomenon. In fact, toxic algal blooms may have been responsible for bird, fish and marine mammal die-offs recorded in the fossil records of Chile's Neogene and Gulf Coastal Florida's Pliocene. Blooms are typically considered to be an indication of decreased ocean health and pollution but there are many other factors that contribute to algal blooms. While Ulva itself doesn't produce toxic chemicals as it grows, the bacteria that decompose the alga once it begins to die can suck the oxygen from the surrounding seawater, suffocating other marine life.

Environmental factors necessary to generate an algal bloom include:

— Sunlight
— High nutrients
— Calm water
— Few grazers or predators
— Temperature
— Salinity

I've been interested in learning more about why we see green tides when we do. To do this, I've been focusing on the microscopic reproductive stages of the green-tide-forming algae, Ulva. In July 2014 I began collecting two liters of seawater every month from San Francisco Bay. I divide the water into culture flasks, add nutrients important to algal growth—such as nitrate, phosphate, ammonium, trace metals and vitamins—and culture it in environmental chambers on the UC Berkeley campus. These chambers are set to simulate summer conditions (16°C, 12-hour days) and every week I replace the seawater with fresh nutrient-enriched seawater. After four weeks I find young Ulva blades and tubes growing on the bottom of my culture flasks. Since I know the volume of the water I originally put into the flasks, I can estimate the number of propagules per liter that were present at the time of collection. I've been repeating this sampling at an additional four locations within San Francisco Bay once every season to estimate variation in spatial distribution of these reproductive stages.

Collecting water samples

I collect monthly water samples from the San Francisco Bay at the Romberg Tiburon Center. Each season I visit four additional locations within the bay to estimate spatial variation in reproductive stage abundances.

Every cell in adult Ulva (blade or tube) has the potential to become reproductive, releasing up to 16 swimming spores from each cell. The cells along the margins of the blades usually become reproductive first; you can see the difference in color between the reproductive cells and vegetative cells in the image at right, below.

Left: These algae (<1cm) grew from reproductive cells of Ulva, also known as sea lettuce. Right: There is a color difference between reproductive and vegetative cells in Ulva. The former are the lighter ones along the margins.

Left: These algae (<1cm) grew from reproductive cells of Ulva, also known as sea lettuce. Right: There is a color difference between reproductive and vegetative cells in Ulva. The former are the lighter ones along the margins.[/caption] Along with the help of some UC Berkeley undergraduates, I am also tracking the settlement of young Ulva at my field site in Tiburon. We have attached settling plates made of resin to rocks in the intertidal zone near the Romberg Tiburon Center. These settling plates are submerged at high tide and exposed at low tide. Each month we return to the intertidal at low tide to collect the plates covered in algae and replace them with sterilized plates. Once back at the lab we use a dissecting microscope to estimate the amount of young Ulva growing on the plates. Now we are working on comparing the amount of young Ulva that grows in the cultures to the patterns of young Ulva we are seeing on the settling plates.

[caption id="attachment_3955" align="aligncenter" width="470"]Algae established on a settling plate A quantity of algae has established itself on this settling plate.

All photos courtesy of Rosemary Romero.

Southern California Spring Break 2015 field trip

Annual field trips used to be something of a tradition at UCMP, but that tradition faded once the Department of Paleontology merged with other units to become the Department of Integrative Biology in 1989. In recent years, former UCMP Director Jere Lipps organized and led three field trips: Baja in 2001, southern California in 2008, and Oregon in 2009. And now two of UCMP’s newest curators, Assistant Professors Seth Finnegan and Cindy Looy, are trying to revive the annual field trip tradition. Seth organized and led a trip to the Kettleman Hills and Death Valley in 2014, and this year, he and Cindy led one to southern California during Spring Break, March 21-28.

On March 21, Seth, Cindy, three UCMP staff (Lisa White, Dave Smith, and Erica Clites), and 11 grad students headed south from Berkeley, with their first stop being a locality south of Soledad along Arroyo Seco Canyon in Monterey County. Here, the group had their first look at the rocks of the extensive Miocene Monterey Formation and found pea crabs, bivalves, and brachiopods. The group would visit more exposures of the Monterey Formation along the California coast — at Gaviota State Park and El Capitan State Beach, west of Santa Barbara — and even as far south as Newport Bay.

Crabs and scallops

Left: Small crab fossils were fairly abundant at the first locality in the Monterey Formation, Arroyo Seco Canyon. Photo by Camilla Souto. Right: Bivalves, such as these scallops, were found at a second locality about a mile away. Photo by Erica Clites.

Gaviota and strike-dip

Top: The strongly dipping exposures of the Monterey Formation at Gaviota State Park, about 33 miles west of Santa Barbara. Bottom: Lisa White (center) takes a strike and dip reading before the students begin measuring a stratigraphic section at the park. Both photos by Camilla Souto.

El Capitan and alga

At both Gaviota State Park and El Capitan State Beach (left), the group found fossils, such as this alga (right), in the Monterey Formation exposures. El Capitan photo by Dave Smith; alga photo by Camilla Souto.

At Piru Gorge, just off I-5 south of Tejon Pass, an attempt was made to relocate some plant localities reported by UCMP alum Daniel Axelrod (A.B., 1933; M.A., 1936; Ph.D., 1938), but without success. East of the gorge and the highway, some road cuts exhibiting nice geological features (cross bedding, ripple marks, etc.) were examined.

Piru Gorge and geology

Top: In Piru Gorge, the group sets off in search of fossil plant localities. Photo by Erica Clites. Bottom: West of Piru Gorge, Caitlin Boas, Seth Finnegan, and Cindy Looy admire the geological features exhibited in a road cut. Photo by Dave Smith.

Jere Lipps — current Director of The Cooper Center, the fossil repository for Orange County — gave the group a tour of the Cooper facility. Afterwards, Jere took the group to a number of interesting localities in the Newport Bay area, including a visit to the Upper Newport Bay Nature Preserve with outstanding views of marine terraces. At the end of the day, Jere and Susie Lipps had the group to their home for a barbecue.

Cooper Center and Newport Bay

Top: Jere Lipps (in all black) gives the group a tour of The Cooper Center. Bottom: Examining another Monterey Formation exposure on the east side of Newport Bay. Note the plastic sheeting draped across the bluff in an attempt to slow erosion. Both photos by Dave Smith.

Anza-Borrego Desert State Park, east of San Diego, was the next stop. The group spent two days looking at the geology exposed at Split Mountain and along Fish Creek Wash in the southeastern corner of the park. The rocks along the wash told some very interesting stories. Moving from east to west, the group examined cobble-filled layers believed to have been deposited by flash floods. Farther on, the rocks showed where an underwater landslide buckled unlithified ocean sediments. Close to the western end of Split Mountain, a series of turbidites — underwater sediment flows that result from slope failures at shelf margins or the distal edges of large river deltas — were observed. Even farther west down the wash, many layers of nearly equal thickness were suggestive of sands deposited out on a vast river delta of shallow slope.

Fold and camp at dawn

Top: Dori and Natalia take a closer look at folded marine sediments, thought to be the result of an underwater landslide hitting the ocean floor nearby. The toe of the unstratified landslide deposit can be seen at the far right. Bottom: A new day dawns at the group’s camp in Fish Creek Wash. Both photos by Dave Smith.

From Anza, the group headed to the Sonny Bono Salton Sea National Wildlife Refuge on the southeast shore of the Salton Sea. Here the group had an initial look at the lake’s beaches covered with dead barnacles and the bones of fish and birds. After a stop to admire some mud volcanoes near one of the 11 geothermal power plants located around the southern end of the Salton Sea, the group headed to the hills above Mecca at the north end of the lake. The group spent its final night in Painted Canyon after taking a hike through it and an adjoining slot canyon.

Salton Sea and mud volcanoes

Top: The shore of the Salton Sea, with a geothermal power plant visible in the distance. Bottom: Ash studies a mud volcano located near one of the geothermal plants. Both photos by Dave Smith.

Painted Canyon and Anza-Borrego sunset

Top: Caitlin, Ash, Dori, Cindy, and Jeff in Painted Canyon. Bottom: A last look across the hills south of Wind Caves in Anza-Borrego Desert State Park. Both photos by Camilla Souto.

After a morning look at some roadside exposures of delta deposits, the group made the long drive back to Berkeley. All participants thoroughly enjoyed the trip and Seth and Cindy are already pondering where to go next year. Will it be the Great Basin? Channel Islands? Italy anyone?

California pollen taphonomy and pollen trap study in Clear Lake, California

Pollen analysis (or palynology) has been used to study Quaternary changes in vegetation and climate in North America since the nineteenth century. Palynologists generally compare plant assemblages in spatial-time frames instead of focusing on particular plant species. These changes in plant assemblages across landscapes through time are a good indication of vegetation shifts caused by environmental changes. Besides using pollen assemblages to reconstruct parent plant communities in a particular area, certain species, which are sensitive to changes in temperature or precipitation, are of special interest. By comparing assemblages of plant communities and these indicative species through time and space, we can infer how regional flora responded to environmental changes such as changes in climate.

Before comparing these past assemblages of plant communities and inferring environmental changes, palynologists carefully consider the processes leading to pollen accumulation. Do their pollen and spore assemblages accurately reflect local or more regional vegetation? Are certain pollen types over- or underrepresented? Does the assemblage include the majority of taxa present in the local plant communities? Pollen assemblages are incorporated in sediments at the end of a long taphonomic pathway, and are affected by temporal and quantitative aspects of pollen and spore production, differential dispersal characteristics, secondary transport, and other taphonomic processes.

How could we get hints of that process throughout geologic time? Wind-pollinated assemblages are most often transported and they are usually produced in large amounts and have wider dispersal ranges. To study the taphonomic process of pollen and spores, palynologists often use surface samples to research the discrepancy between vegetation composition and pollen assemblages. Such analysis also might help to understand the taphonomic conditions in the sample area and provide a reference point for a regional paleopalynological study.

First version of pollen trap

First version of a modified Olefield pollen trap (Jantz et al. 2013).

For my dissertation research, I am compiling a California pollen reference collection. Focused on the last interglacial period, I plan to reconstruct the vegetation from a relatively warm period during that time interval. My methods involve extracting pollen from core samples from Clear Lake. Clear Lake is the largest lake in California with a sedimentary record going back at least to the last interglacial period (~130 ka) (see Scientists core into Clear Lake to explore past climate change). The microscopic pollen grains are expected to yield important clues on the history of vegetation communities and the taphonomic process surrounding Clear Lake; data from pollen traps set in different vegetation areas in the vicinity of the lake — forests up to 2 km from the lake, or small, more distant upstream communities — will enable further analysis of modern vegetation types.

The most common pollen in Clear Lake samples is wind-pollinated, mostly pine and oak pollen. An important question is: does this pollen mainly originate from the northwestern forests, the southwestern forests, or other adjacent places? To solve this question, I started to look for appropriate types of pollen traps to collect surface samples and, with the help of my undergrads, Mary Grace Rodriguez and Rebecca Shirsat, we built some traps to position in the field.

After visiting the Clear Lake area a couple of times, I positioned the first 10 pollen traps close to the lake — many thanks to Carolyn Ruttan from Lake County Water Resources who helped me obtain landowners' permits for this.

The first time doing field research is often filled with anticipation. On January 20, I left Berkeley in the early morning. I was so excited — not only because I could finally install my pollen traps, but because it would be only my second time driving through winding mountain roads!

After meeting Carolyn Ruttan I set off to Clear Lake State Park, our first pollen trap site. I selected a rocky corner of the lake that had a gorgeous view. Securing this first pollen trap to the ground was a challenge, but we stabllized the base with pebbles and used a small iron wire to prevent the trap from blowing over in the wind.

The next trap was easier to position, being on soft soil in Anderson Marsh. We only had to avoid picking a spot where weeds might cover the area later in the year.

The Lake County Land Trust’s Rodman Preserve is another one of my research sites. The trust was formed as a non-profit organization in 1994 and it works to protect important land resources, wetlands, forests, etc., in Lake County, CA.

Preparing to install a trap and one in the Rodman Preserve

Left: Preparing to install pollen traps in Clear Lake State Park. Right: Pollen trap in the Lake County Land Trust's Rodman Preserve.

The Elem Indian Colony, near Clearlake Oaks on the eastern shore of Clear Lake, is my fourth research site. It is a Native American colony of Pomo, associated with the Sulphur Bank Rancheria. The residents were friendly and curious about our purpose. I am sure they will help prevent tourists from removing the trap that we placed near a power station.

We then attached pollen traps to railings and floating platforms at three sites. Installation of the first 10 pollen traps was completed on this first trip; we went back two weeks later to complete the west side of the lake.

Pollen traps on platforms

Two pollen traps attached to floating platforms.

The most serious threat to my traps is the strong winds around Clear Lake, especially on the northwest side. Strong, seasonal winds can take down deeply-rooted trees and it could damage the pollen traps. Squirrels and birds might also be a problem but hopefully, the iron wires we used will keep them safe from animals. I plan to return to Clear Lake later in the year to replace trap materials and to see what my pollen traps have collected (if the squirrels and birds have not absconded with my trap materials)!

The hunt for a Ph.D. thesis: Collecting Late Cretaceous plant fossils in New Mexico

"It ain't Mexico and it ain't new" [quoted from a postcard in a gift shop]

Armed with hammers, chisels, pry-bars, boxes of newspaper, and sunscreen, two trusty assistants (recent graduate Meriel Melendrez and current undergrad Nicolas Locatelli) and I drove from Berkeley in our 4WD extra-long SUV heading for southern New Mexico. There, we met up with paleobotanist Dr. Gary Upchurch and crew from Texas State University and geologist Dr. Greg Mack from New Mexico State University for two weeks of field work in Late Cretaceous plant localities of the Jose Creek Member. It was a bona fide tri-state expedition working on multiple projects. My interests were to set the foundation for my dissertation work on the ecological diversity of Late Cretaceous forests in warm-wet climates. For this I needed a primary study site to generate new collections and data. The trip wasn’t entirely exploratory — I was familiar with some of the localities from my undergraduate days with Dr. Upchurch, and had collected here previously. Based on this earlier work, we knew that there was an abundance of plant fossils, and preliminary studies have indicated that the fossil assemblages of the Jose Creek Member represent a subtropical-paratropical forest. That’s right, in the present day desert of New Mexico, rich in angiosperms but mixed with conifers and ferns.

Late Cretaceous plant communities often contain interesting combinations of plants that are no longer found living together under the same climatic conditions (for example palms and redwoods). That is because the Late Cretaceous represents an important transitional time, as flowering plants (angiosperms) rapidly diversified and rose to dominance in warmer climates. During this time, the typical early to mid-Mesozoic forests that were dominated by ferns and gymnosperms (conifers and other non-flowering seed plants) transitioned to the modern, angiosperm-dominated forests. This begs several questions: what were the different ecological roles of angiosperms and conifers in these forests, and did conifers and other gymnosperms serve functions that have now been replaced by angiosperms? How has the structure of plant communities in warm-wet climates changed from the Cretaceous to present, and how does this inform our understanding of the evolution of modern tropical forests? These are the questions that fueled my quest into the southwest last summer. The New Mexico sites seemed like an ideal place to start my investigations, and we ambitiously set out to do some major collecting.

In the Jose Creek Member, the best-preserved plant fossils come from beds of recrystallized volcanic ash. My initial goal was to collect quadrats from multiple volcanic ash beds, which would give an indication of the vegetation through time (because beds are not necessarily deposited at the exact same time). But things don’t always work out like you plan, and luckily this was one of those times ….

Field site

Field site on the distant hills (can you see the exposure?), but with modern vegetation of course! Photo by Meriel Melendrez.

Dori with palm frond

Fossil palm frond (with Dori for scale). Photo by Meriel Melendrez.

Preparing a collecting site

Meriel and Nick preparing a collecting site. Photo by Dori Contreras.

The first locality we went to had an ash bed that was known for its abundance of plant fossils and beautiful preservation. After setting up the first collecting quadrat with Meriel and Nicolas, Dr. Mack and I headed off to investigate how far we could track the exposed bed, as its lateral extent was hitherto unknown. To our amazement, we were able to track the deposit for ~1.2 km! This was an incredible revelation; here were the remains of a forest preserved in ash for quite an impressive spatial extent, which would enable the reconstruction of a plant community at a single instant in time. This was considerably more attractive for my questions than reconstructing vegetation from multiple beds comprising an unknown amount of geologic time. I adjusted plans and concentrated our efforts on this deposit alone (rather than a compilation of sites) and spent the next nine days collecting small quadrats along the length of the bed. The deposit is so rich that virtually every rock we cracked open had multiple fossil plant specimens! Consequently, almost everything we touched was wrapped in newspaper, hiked out of the field site, and brought back to the UCMP. This was no light task — thank goodness for the incredible Meriel and Nicolas! In total we collected samples from 14 sites along the exposure. These initial collections reveal a rich and laterally diverse flora, and yet are only the tip of the iceberg!

We headed back west with the SUV packed to the brim and riding low from the weight of the fossils; it was the maximum that could possibly be brought back. I should also mention — Cindy Looy and Ivo Duijnstee, along with some of the other Looy Lab members (Jeff, Renske, Robert) — were in New Mexico for a conference and we arranged to meet them. This was particularly fortuitous, not only for good company, but also because they took two large tubs of fossils back with them! Another two tubs went back to Texas, and made it to Berkeley later that summer. All in all, it was enough fossils to fill two double-door cases in the museum!

Of course, the field work is only the beginning and, since then, a lot of work has gone into getting these first collections organized and examined. Currently, two students (James Buckel and Negin Sarrami) and I are describing and photographing leaf morphotypes from the collections to assess the diversity of plants in the flora. A large portion probably represent unknown/undescribed species, so we differentiate ‘species’ as morphotypes based on detailed descriptions of leaf characteristics. The flora includes a diversity of herbaceous and woody ‘dicots’, monocots (e.g., palms and ginger), cycads, ferns, an abundant extinct sequoia-like conifer and several extinct conifers probably related to the Araucariaceae. Overall, it is clear that it will take several more field excursions and countless hours of lab work to understand the taxonomic and structural diversity of this amazing flora. And, of course, I am eagerly looking forward to the return trips and uncovering the treasure trove of fossils still entombed in the rock out in the desert!

Fossil fern

Fossil fern. Photo by Dori Contreras.

Angiosperm leaf

Angiosperm leaf with insect feeding damage (holes). Photo by Dori Contreras.