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Cal Day 2007 features UCMP research

Cal Day 2007 was another smashing success. The ever-popular tours of the collections and "Fun with Fossils" activity were complemented by two lectures: Marine Mammals of the California Coast Through Deep Time presented by Nick Pyenson and A Deadly Equation: Global Warming + Humans = Ecological Catastrophe by Tony Barnosky, and a new tee shirt design debuted, thanks to the artistic skills of Dave Smith. Visitors had the opportunity to enjoy displays that included Chilean forams and ostracodes, whale-falls, mammoths, Triceratops ontogeny, petrified forests, Miocene marine fossils, gastropod protoconchs, and travels to Baja, as this year's Cal Day focused on the diversity of field research projects of UCMP.

Identifying new paleontological sites in Tanzania
Since 2006, Leslea Hlusko and Dr. Jackson Njau of the Tanzanian National Natural History Museum have been co-directing a survey project designed to identify new paleontological sites in Tanzania, focusing on sediments from the last 10 million years. Their goal is to inventory and document new paleontological and archaeological sites and to make these known to the Tanzanian cultural heritage authorities and other researchers. For CalDay, Leslea and three students from her lab (undergrads Liz Bates and Ellen Young, and grad student Theresa Grieco) had a chance to tell the public about how this field research is being carried out, and to show some of the famous stone tools and casts of hominid fossils previously found in Tanzania.

Students in Leslea Hlusko's lab are all smiles as they prepare to discuss the Tanzania project with Cal Day visitors Leslea was kept busy answering questions for an inquisitive Cal Day crowd
Left: Students in Leslea Hlusko's lab are all smiles as they prepare to discuss the Tanzania project with Cal Day visitors. From left are undergrads Liz Bates and Ellen Young, and grad student Theresa Grieco. That's Leslea behind Ellen, talking to a visitor about some known Tanzanian fossil localities. Right: Leslea was kept busy answering questions for an inquisitive Cal Day crowd.
 

A cranial growth series in Triceratops
A postorbital horn from a subadult Triceratops
A postorbital horn from a subadult Triceratops. Note how the horn curves backwards. In studying an ontogenetic series of skulls, Mark Goodwin and Jack Horner have observed that as Triceratops ages, the horns begin to point more forward.
 
Triceratops, everyone's favorite three-horned dinosaur, seemed to imbue our Cal Day efforts: the two skulls in the lobby of the Biosciences Library, the latest UCMP tee shirt design, and a display of fossils by Mark Goodwin. Mark has been working with Jack Horner from the Museum of the Rockies to examine Triceratops cranial growth series of at least 12 skulls and over 20 partial skulls and numerous individual cranial elements from the Late Cretaceous Hell Creek Formation in eastern Montana. Of particular interest are the unique dermal ossifications, such as the nasal horn,"beak," bony knobs, and ornaments that are expressed later in Triceratops ontogeny. Historically, most early collectors and major museum field parties preferred complete skulls and the bigger the better, resulting in the collecting of dozens of adult Triceratops over the decades, but few subadult, juvenile and baby skulls — until now!

Discovery of a Miocene whale-fall at Año Nuevo
While preparing the fossil skeleton of a baleen whale found in 1987 on the Año Nuevo Island Reserve, Nick Pyenson noticed a number of unusual bivalves affixed in deep crevices of the whale's skull. Nick showed the bivalves to museum scientist David Haasl, who recognized the association as a potential example of a fossil whale-fall. Modern examples of whale-fall communities are well documented from deep-sea environments, where large, sunken whale carcasses provide enough nutrients to sustain a unique community of deep-sea invertebrates. Such associations are known in the fossil record from Oligocene and Miocene localities in Washington and Japan, but this discovery is the first for California and is also among the youngest, being no more than 15 million years old. The large number of mollusks and the small size of the whale (‹ 4 m long in reconstructed length) challenge previous hypotheses that large carcasses (1020 m long) are required to sustain fully-developed, modern whale-fall communities.

Excavation of the baleen whale in 1986 and how the site looks today Bones of the fossil baleen whale discovered on A&241;o Nuevo Island
Left: Excavation of the baleen whale bones in 1986 (left) and how the site looks today, with Dave Haasl for scale. Right: Bones of the fossil baleen whale discovered on Año Nuevo Island. Small bivalves found in crevices in the skull suggest that the whale carcass sustained a community of invertebrates when it lay at the bottom of a Miocene sea.
 

Comparing developmental strategies in extinct and extant gastropods
Using living specimens, her laptop, and a microscope, Jann Vendetti introduced our visitors to her research on the development and larval evolution of extant and extinct marine gastropods in the family Buccinidae. These are abundant, diverse, and highly derived gastropods that vary in their larval strategy, called "developmental mode," during early ontogeny. These developmental differences are reflected in the shape (and other characters) of gastropod larval shells and in the first coils of an adult gastropod's shell apex (i.e., the protoconch). Jann studies both the larval shell and the protoconchs (using scanning electron microscopy) to gain insight into the early life history of living and extinct species within the Buccinidae.

A sample of buccinid gastropods that Jann Vendetti is looking at Jann hopes that her enthusiasm for her gastropod studies will inspire these two future scientists
Left: A sample of buccinid gastropods that Jann Vendetti is studying. Top row, from left: Kelletia kelletii, Neptunea despecta, Neptunea latus, Neptunea fukueae, Macron aethiops, Bablyonia japonica, Northia northiae. Bottom row, from left: Burnopena papyratia, Solenosteira macrospira, Siphonalia fuscolineata, Solenosteira sp., Cantharus pallidus, Macron aethiops; fossil taxa: Bruclarkia barkeriana, Bruclarkia columbiana, Bruclarkia blakelyensis, Bruclarkia oregonensis. Right: Jann hopes that her enthusiasm for her gastropod studies will inspire these two future scientists.
 

Exploring Sharktooth Hill bonebed origins
The Sharktooth Hill bonebed in Kern County, CA is widely known for its shark teeth (hence the name); however, it also preserves a wide variety of marine animals that lived in the North Pacific during the middle Miocene, around 16 million years ago. UCMP has a long history with this site and recently, UCMP grads Nick Pyenson, Randy Irmis, and UCMP curator Jere Lipps have been working to better understand how the Sharktooth Hill bonebed was formed, and what processes occurred during its preservation to account for the high density of marine vertebrate bones and teeth. Nick and Randy are examining crucial data on the identity, abrasion, and condition of bones that make up the bonebed. These data can falsify some current hypotheses about the bonebed (e.g., it was a calving ground for cetaceans, or it is a catastrophic mass-death assemblage). The team will also test different models of sedimentation rates to add to our understanding.

Nick Pyenson and Randy Irmis talk to Cal Day visitors about the wealth of fossils excavated at Sharktooth Hill Fossil skull from a Sharktooth Hill sea lion
Left: Nick Pyenson (far right) and Randy Irmis (second from right) talk to Cal Day visitors about the wealth of fossils excavated at Sharktooth Hill. Right: This fossil skull from a Sharktooth Hill sea lion Allodesmus kernensis, was on display.
 

A new explanation for a Chilean microfauna
Foraminifera and ostracodes may be the size of sand grains, but they can provide a wealth of data about the past. These critters live at all ocean depths, but depth-related environmental factors control the distributions of bottom dwellers, and that makes their fossil counterparts useful in determining where sediments accumulate. Ken Finger and Dawn Peterson have been studying microfossil assemblages from numerous outcrops and boreholes in south-central Chile, particularly the Navidad Formation that Charles Darwin named after he visited the region in 1835 and collected a rich molluscan fauna that indicated coastal uplift. Subsequent studies defined this as a shallow marine fauna from the early to middle Miocene (23 to 11 million years ago). The microfossils extracted from the rocks that Ken and Dawn are studying tell a different story. They found the microfauna to be a mix of species derived from a wide range of depths and ages, which they attribute to earthquakes along the nearby Peru-Chile trench. Such quakes would have triggered downslope transport of unconsolidated sediments. The deepest-dwelling indicators reveal that Navidad deposition was below 1500 meters, and the youngest-age markers indicate this occurred about 4.2 to 4.6 million years ago in the early Pliocene.

Museum scientist Ken Finger and volunteer Dawn Peterson are happy to 'spread the word' about foraminifers The foram Globorotalia puncticulata
Left: Museum scientist Ken Finger (second from left) and volunteer Dawn Peterson (arms folded) are happy to have an opportunity to "spread the word" about foraminifers. Right: Three views of the foram Globorotalia puncticulata, one of several forams and ostracodes used in the Chile study.
 

Answering questions about a Nevada petrified forest
Museum scientist Diane Erwin shows a young visitor thin sections of petrified wood
Museum scientist Diane Erwin shows a young visitor thin sections of petrified wood.
 
Like the victims of Pompei, the giant tree stumps of Nevada's George W. Lund Petrified Forest stand as they were, entombed in volcanic ash. But these trees are providing evidence of their ancient ecosystem. Working in conjunction with the Bureau of Land Management (BLM) and US Forest Service, Diane Erwin is helping to conserve the forest, while addressing the many scientific questions inspired by this once thriving community. What are the trees and how can we identify them? When did this forest live? Can we determine if the forest was a climax community? Did the trees ever experience wildfires? Has the forest always been in this part of Nevada? Was it the ash, climate change, or something else that killed the trees? Cal Day visitors learned that to answer these questions, researchers are studying the area's geologic history. Also, because the Lund fossil tree rings (annual growth rings) are so well preserved, tree ring analysis methods can be used to decipher the trees' life histories. Learn more about the tree ring methods.
 

Museum scientist Ken Finger and volunteer Dawn Peterson are happy to 'spread the word' about foraminifers The foram Globorotalia puncticulata
Left: Laura Levy and Regina Smith of the Bureau of Land Management (center and right, respectively) watch as former UMCP preparator Jane Mason applies adhesives to a fossil stump to slow down the effects of weathering. Right: One of the many large upright stumps of the Lund forest.
 

Cal Day photos of Hlusko lab, Leslea Hlusko, Jann Vendetti, Nick Pyenson and Randy Irmis, Ken Finger and Dawn Peterson, and Diane Erwin by Scott Fay and Liz Perotti; Triceratops horn and fossil sea lion skull by Judy Scotchmoor, © UCMP; Año Nuevo photos courtesy of Dave Haasl and Nick Pyenson; buccinid gastropods by Jann Vendetti, © UCMP; Globorotalia puncticulata images courtesy of Ken Finger; Lund forest photos by Diane Erwin, © UCMP.