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Archive for May 2010

Global warming and declining mammal diversity: new research in Nature

Pleistocene survivor, the deer mouse.  Photo by Glenn and Martha Vargas © California Academy of Sciences

Pleistocene survivor, the deer mouse. Photo by Glenn and Martha Vargas © California Academy of Sciences

Popular images of Ice Age California tend to feature enormous, extinct mammals like mammoths and saber-toothed cats.  By contrast, new research published in Nature examines populations of small mammals that survived through the end of the Ice Age and how they were affected by the climate change.

The research team of Jessica Blois (formerly at Stanford, now at University of Wisconsin, Madison), Elizabeth Hadly (formerly of UCMP, now at Stanford) and Jenny McGuire (UCMP) studied fossilized woodrat nests collected from Samwell Cave in Northern California.  Woodrats carry scat and regurgitated pellets produced by carnivores back to their nests.  These collections are filled with undigested small mammal bones, making fossilized woodrat nests treasure troves for paleontologists.

Comparing fossil data to modern small mammal populations in the same region revealed a big decrease in diversity during a period of global warming at the end of the Pleistocene Epoch.  There was a decrease in both species richness (number of different species) and evenness (relative dominance of species within a community).  A few species disappeared from the area entirely.  Some species remain in the area but as a much smaller proportion of the overall small mammal community.  And the main species to increase in relative abundance was the deer mouse — an animal that can tolerate a wide variety of habitats and climates.

Research of historic periods of global warming improves our understanding of how modern, man-made global warming will affect life on Earth.  Read more about this research:

Marine vertebrate paleontology in Half Moon Bay

Paleontology along California's coastline

Paleontology along California's coastline. A) Fieldwork on the coast often involves climbing up ledges to get access to just one more meter of outcrop. B) A fossil tooth of the great white shark, Carcharodon carcharias. C) A freshly collected tympanic bulla of an extinct porpoise (Phocoenidae).

This week, we welcome guest blogger Robert Boessenecker. Bobby has been interested in paleontology since he was a kid. He grew up in the Bay Area; when he found Miocene shark teeth in the Santa Cruz Mountains, he was hooked.  He first got involved with the UCMP when he was a high school freshman — he visited the museum with his dad, to interview UCMP Assistant Director Mark Goodwin for a school project. Bobby is now getting a Masters' degree at Montana State University. He studies the taphonomy and preservation of marine vertebrate fossils in the Mio-Pliocene Purisima Formation of Central California.

After the completion of my first year of college, I was relaxing during my family's annual vacation at Lake Tahoe. While at the beach I received a phone call from my uncle; a surfing buddy of his had discovered a bunch of fossil bones somewhere near Half Moon Bay. I was excited, primarily because few discoveries of fossil vertebrates had been made along the San Mateo County coastline. I knew that much of the county's shoreline was made of the Purisima Formation, a rock unit I was familiar with from collecting fossils in the Santa Cruz area.

The Purisima Formation is late Miocene and Pliocene in age (7-2.5 Mya). In the Santa Cruz area, fossils of sharks, rays, skates, bony fish, sea birds, walruses, fur seals, dolphins, belugas, baleen whales, and sea cows had been discovered. With such a diverse fossil assemblage, I knew there was serious potential for discovery at this new spot in Half Moon Bay.

A day or two after we returned from Tahoe, my friend Tim Palladino and I followed directions to the locality, and sure enough, it was all Purisima Formation. When we arrived, the exact spot the surfer pointed out was up along a two foot wide ledge overhanging a thirty foot drop to the beach; neither of us were crazy enough to try climbing up there, and we decided to explore elsewhere. Shortly thereafter, we discovered several bonebeds with abundant bones and invertebrate shells preserved. Because the locality was on government-owned land, collecting without a permit was illegal.

After returning to Montana for my second year of college, I applied for (and eventually received) a permit, so that I could return to the locality and establish a collection. In summer 2005, I returned, and discovered a fossil skull of a baleen whale. The excavation took four days and half a dozen volunteers, but eventually the skull was excavated and wrapped in a plaster jacket for safe transport back to Montana. After the plaster jacket was removed that fall, I found that the skull was also encased in a concretion — the sandstone closer to the middle of the skull had been cemented with calcium carbonate, the same mineral in limestone. Needless to say, preparation took four and a half years, and was only finished in March 2010.

In 2006 I returned to the locality. We made two major finds that summer: the nearly complete skull of a fossil porpoise, and a complete lower jaw of the "'dwarf"' baleen whale Herpetocetus. In addition to these finds, by the end of 2006 I had collected several shark teeth (including those of great white sharks, basking sharks, angel sharks, a mako shark, and even a sawshark), fish bones, the humerus of an extinct flightless auk (Mancalla diegensis), bones and teeth of a walrus and a fur seal, and multiple ear bones of porpoises and several baleen whales (Herpetocetus, a right whale, and a rorqual whale). All of this fossil material is currently under curation for UCMP collections. UCMP has more fossil material from the Purisima Formation than any other repository, and now it is the recipient of an entirely new fossil assemblage from the Purisima. All in all, the collection includes several hundred specimens that represent 22 different species of marine vertebrates.

To learn more about Bobby's research, check out his blog, The Coastal Paleontologist.
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Think Evolution II: a summer institute for science educators

thinkevo_blogJoin us at the UCMP for a fun-filled five days of evolutionary explorations with biologists and educators from the University of California. On August 2-6, UCMP and the National Center for Science Education will host a workshop for middle school, high school, and community college biology teachers and science educators. Scientists will discuss their research, covering topics like molecular evolution, developmental biology, and human evolution. Learn how you can integrate cutting-edge evolutionary research into your curriculum. For more information about the workshop, including registration information, click here.

Last year's Think Evolution workshop was a great success — check out some photos from the workshop, below.

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Special exhibit: Fossil eggshell

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This week, we've launched a new online special exhibit — Fossil eggshell: Fragments from the past. This is the best online source of information about fossil eggshell — you can't find this info anywhere else!  This special exhibit was created in collaboration with Laura E. Wilson, Karen Chin and Emily S. Bray, from the University of Colorado, Boulder, and Frankie D. Jackson from Montana State University.

We can learn a lot from fossil eggshell. Using scanning electron microscopy, we can examine the details of the shell morphology and structure. This provides clues as to the identity of the egg-layer; different groups of animals have very different types of shells. Fossil eggshell can also tell us about the ecology and behavior of the egg-layers — and their babies.

This online special exhibit features a case study of the Willow Creek Anticline in the Two Medicine Formation, Montana, where paleontologist Jack Horner and colleagues found numerous dinosaur eggs and eggshell fragments. Read about the discovery of the fossils, and what Jack and his colleagues learned about the egg-layers — dinosaurs Maisasaura and Troodon — through their detailed analyses of the fossil eggshell.

Much of the material in the online exhibit comes from the Hirsch Eggshell Collection at the University of Colorado Museum of Natural History. The collection was donated by eggshell enthusiast Karl Hirsch who made significant contributions to the field of fossil eggshell research. Learn about his legacy in the special exhibit section Karl Hirsch and the Hirsch Eggshell Collection.

UCMP's Tony Barnosky on Science Friday

barnosky_scifriMounting evidence suggests we may be on the cusp of a major extinction event. Last week, UCMP Faculty Curator Tony Barnosky talked about modern extinctions on Science Friday, a weekly science talk show on NPR. Tony was joined by Barry Sinervo, Professor at UC Santa Cruz, George Amato, of the Sackler Institute and the American Museum of Natural History, and Vance Vredenburg, Assistant Professor at San Francisco State University. In a lively conversation, Tony and the guests discussed many examples of animals and ecosystems currently affected by global warming. If you missed the program last week, you can listen to it here.

Tony is the author of Heatstroke: Nature in an Age of Global Warming. To learn more about his work, check out the Barnosky Lab website.

On May 17, Tony Barnosky gave the 2010 Integrative Biology Commencement Address, which he titled Geography of Hope, a line he borrowed from Wallace Stegner. Tony discussed the biological and global issues that will challenge the Class of 2010 — and how these graduates represent his hope for the future. Read Tony's commencement address, Geography of Hope, here.

Tony was involved with a BBC radio broadcast (May 2012) about the possibility of our being in the midst of a sixth mass extinction.

Evo in the news: Making sense of ancient homonin DNA

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Denisova Cave, where the fossil finger was discovered. Photo provided by ЦуваевНиколай at ru.wikipedia and shared via Creative Commons.

When archaeologists discovered a 40,000 year old pinky bone in a Siberian cave, everyone wondered who the bone belonged to. Researchers extracted DNA from the fossil and used it to construct an evolutionary tree to see how the pinky bone's owner was related to modern day humans and Neanderthals. Scientists were surprised by what they found — read more about it in this month's Evo in the news: Making sense of ancient homonin DNA.

Each month, the UCMP's Understanding Evolution website features an Evo in the news article, which focuses on the evolutionary aspects of a popular news story. Click here to browse the Evo in the news archive!

Congratulations Tim White!

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Tim White. Photo: Discovery Communications, LLC.

Congratulations are due to Tim White, Director of the Human Evolution Research Center and Faculty Curator at the UCMP! Tim was selected by Time Magazine as one of The 100 Most Influential People in the World. Tim receives this recognition for his work on human evolution. This past fall, Tim and his colleagues published numerous papers on Ardipithecus ramidus, the oldest and most complete skeleton of a human ancestor. Congratulations, Tim!