PaleoBios Museum of Paleontology University of California, Berkeley Volume 18, Supplement to Number 1 ISSN 0031 -0298 March 22,1997 1997 California Paleontology Conference Berkeley, California Program and Abstracts GENERAL INFORMATION PaleoBios is published on an occasional basis by the University of Cali- fornia Museum of Paleontology. Since its inception in 1967, PaleoBios has published papers on all aspects of paleontology. Current circulation includes over 300 institutional and private subscribers worldwide. PaleoBios publications are indexed in the Zoological Record and in GEOREF. PaleoBios is a peer-reviewed journal. We welcome submissions of manu- scripts from authors not associated with UCMP. PaleoBios has a home page on the World Wide Web, which can be found at http://ucmpl.berkeley.edu/museum/PBSI.html. Guidelines for contributors can be requested from the editor, found in the back of the first issue of each volum or found online at http://ucmpl.berkeley.edu/museum/PBGUIDE.html. Please contact the editor for more information on the publication of symposia and abstract volumes. Information on subscriptions and back issues may be found online at http://ucmpl.berkeley.edu/museum/list.html, or may requested from the editor. Subscription price (including postage) is $10.00 per volume, payable in U.S. dollars. Please address all correspondence to: Editor, PaleoBios, University of California Museum of Paleontology, Berkeley, CA 94720 , or (e-mail) to pbios @ucmp 1 .berkeley.edu EDITOR: Robert P. Guralnick ASSISTANT EDITOR: Thomas Stidham EDITORIAL BOARD: Nan Crystal Arens, William A. Clemens, David R. Lindberg PaleoBios Volume 18, Supplement to Number 1 Pagel Welcome to CalPaleo! The 1997 California Paleontology Conference at UC-Berkeley coincides with the celebration of the 75th anniversary of the founding of the UC Museum of Paleontology, and the 125th anniversary of the founding of the research collections. In 1874 the California State Legislature designated Berkeley as the state's fossil repository. The founding of the Museum of Paleontology occurred in 1921 as a result of the efforts of Annie Alexander, a former student and benefactor. In the past few years some important changes have taken place in the organization of the paleontology research facilities at Berkeley. In 1995, UCMP relocated from McCone Hall to a larger facility with state-of-the-art laboratories in the newly renovated Valley Life Sciences Building. The move finalized the end of the Department of Paleontology at Berkeley, which was added to the newly founded Department of Integrative Biology in 1989. Paleontology graduate students no longer share offices and study space with the UCMP research collections, but work in a variety of faculty laboratories. UCMP still serves as an important research collection for students and faculty in Integrative Biology, and for the research community at large. In addition to an broad spectrum of talks demonstrating the diversity and utility of paleontological data, this year's conference includes an opportunity to familiarize yourself with the changes that have taken place at Berkeley since the move in 1995. Tours will be provided of the new museum collection space, laboratories, and computer facilities (used, in part, to maintain our World Wide Web site). We hope you enjoy the conference, and look forward to seeing you at UCMP in the future. Ross Nehm, Conference Chair Pat Holroyd, Logistics and Field Trip Rob Guralnick, Abstracts Carol Tang, Field Trip Page 2 1997 CalPaleo Abstracts PaleoBios 18(1) Supplement California Paleontology Conference Program Friday, March 21 6:00-8:00 PM. Registration, Welcome Reception, Museum Tours University of California Museum of Paleontology, Floor 1. Valley Life Sciences Building. Museum Tours: Dr. Pat Holroyd, Museum Scientist, Rob Guralnick, Graduate Research Associate. Saturday, March 22, Morning Events 9:00-10:00AM. Morning coffee and poster session. Room 2063 Valley Life Sciences Building, Floor 2. Poster Participants: John Hutchinson, Department of Integrative Biology, UC-Berkeley Marta deMaintenon, Department of Integrative Biology, UC-Berkeley Joseph Skulan et. ah, Department of Integrative Biology, UC-Berkeley Robin Weber, Department of Integrative Biology, UC-Berkeley Selected posters from Berkeley students associated with the Museum of Paleontology 10:10AM. Conference Welcome, Dr. David Lindberg, Acting Director, UC-Museum of Paleontology, Professor of Integrative Biology Room 2040 Valley Life Sciences Building 10:30AM. Contributed Abstracts, Sesssion 1. Session Chair: Ross Nehm 10:30AM: John Bragin, UCLA Center for the Study of the Evolution and Origin of Life. The Martian "Fossils": A case study in Scientific Confirmation and the Public Purse. 10:50AM: Richard P. Hilton and Patrick J. Antuzzi, Sierra College, CA. Chico Formation Yields Clues to Upper Cretaceous Paleoenvironment in California. 11:15AM: Robert Guralnick, Dept. Of Integrative Biology, UCB. Origins of Deep-Sea Pattelogastropods: Offshore Relicts or Onshore Origination? PaleoBios 18(1) Supplement 1997 CalPaleo Abstracts 11:35AM: Bryan Bemis, Howard Spero, Jelle Bijma, and David Lea, Dept. of Geology, UC-Davis. Reassessing Oxygen Isotope Variability in Planktonic Foraminifera: Implications for Sea Surface Temperature Estimates. 11:55PM. Lunch Recess. Saturday, March 22, Afternoon Events 1:30PM. Contributed Abstracts, Session 2. Session Chair: Carol Tang Room 2040 Valley Life Sciences Building 1:30PM. Adrienne Blair, Molecular Biology Institute, UCLA. A_ Comparative Study Between the Drosophila and Tribolium Even- Skipped Promoters and the Evolution of Segmentation. 1:50PM. Glen Kinoshita, Dept. of Geological Sciences, Cal State Polytecnic University. Community Floral Associations of the late Miocene Puente Formation, Chico Hills, CA. 2:10PM. Sarah Boyer, Dept. of Integrative Biology, UCB. The Evolution of Diadromy in Neritid Gastropods of the Tropics. 2:30FM.Coffee break. Room 2063 Valley Life Sciences Building, Floor 2. 3:00PM. Contributed Abstracts Session 3. Session Chair: Ross Nehm Room 2040 Valley Life Sciences Building 3:00PM. Christopher House. Dept. of Earth and Space Sciences, UCLA. Pseudofossils and Microfossils-Important Differences. 3:20PM. Sherri Gust. George C. Page Museum, LA. Size and Sexual Dimorphism in Smilodon from Rancho la Brea. 3:40PM. David Lawler and Howard Shorn, UCMP, Berkeley. Paleogene Floras of the Northern Sierra Nevada: Tecton-Geomorphic Implications. 4:00PM. Karen Whittlesey. Dept. of Earth Sciences, USC. Miocene Mudsticking Monstrosities: The Tall Tale of Tamiosoma. Page 4 1997 CalPaleo Abstracts PaleoBios 18(1) Supplement 4:20PM. Adam Woods. The Role of Environmental Conditions in Determining the Timing and Behavior of Biotic Recovery from Mass Extinctions: An Example from the Early Triassic. Saturday, March 22, Evening Events 5:00PM. Museum Tours II: Dr. Pat Holroyd, Museum Scientist. University of California Museum of Paleontology, Floor 1. Valley Life Sciences Building. 6:30-8:00 PM. Conference Dinner. UC-Museum of Paleontology, Floor 1, Valley Life Sciences Building. 8:00PM. Plenary Speaker: Dr. Kevin Padian, Professor of Integrative Biology, Room 2040 Valley Life Sciences Building Sunday, March 23 9:00AM Geology/Paleontology Field Trip, Dr. Carol Tang, Organizer Please contact Carol to arrange rides and time. PcieoBios 1F(1) Supplement 1997 CalPaleo Abstracts Page 5 VLSB 1st FLOOR NORTH Friday reception & museum tours Sat p.m. dinner AFO WOOD SHO! 1130 ft ft 1170 LSC COMPLEX SHOPS k-r-ft-- DUNCAN OFFICE SCHMID S.OFFICE UCMP SCIENTISTS OFFICE CONNECTOR TO LSA Page 6 1997 CalPaleo Abstracts PaleoBios 18(1) Supplement VLSB 2nd FLOOR NORTH ACADEMIC] FACILITIES OFFICE Meeting talks (Saturday) ACADEMIC COORD. BIO 1A GSI OFFICES PaleoBios 18(1) Supplement 1997 CalPaleo Abstracts Page? California Paleontology Conference <97 Field Trip To The Merced Formation The Merced Formation is exposed along sea- side cliffs south of San Francisco from the Fort Funston area in the Golden Gate Recreational Area to Mussel Rock in northern Pacifica. The geology and paleontology of these Pleistocene outcrops have been studied recently by Clifton et al. (1988) and Clifton (1988), and summarized in numerous field trip guides (e.g., Clifton and Hunter, 1987, 1991; Hunter et al, 1984). Although extensive landsliding of poorly-consolidated Merced and Colma Formation sediments can greatly obscure sedimentological and paleontological features, strata representing a range of marine and non-ma- rine coastal depositional environments are visible along the 7 km outcrop. Both trace and body fossils of invertebrates and vertebrates have been found within the Merced Formation. ACCESS TO MERCED COASTAL EXPOSURES Access to the coastal cliffs of the Merced For- mation can be obtained from Fort Funston on horse trails and from a trail leading down from the hanglider viewing area. The visitor's center at Fort Funston has a small display on the birds, flora and sand dunes of the area. At the beach, the Merced Formation is exposed both to the north and south. Trace fossils have been observed north of the Funston coastal access trail while a dark, fossil hash unit is exposed to the south at the base of the cliffs. Fort Funston is part of the Golden Gate Recreational Area and is accessible from southbound Skyline Boulevard. Due to a large slump/landslide of the Merced Formation, the road to Thornton State Beach is now closed and its parking lot has become replaced with a field of native flora. However, there are still horse trails which lead from Skyline Boulevard to the beach. The Merced Formation is exposed both to the north and south of Thornton Beach. To the south, the beds are much more tilted and thus, a series of units intersect the beach. The closed road which led to Thornton State Beach can be reached by exiting Interstate 280 at the Westlake District exit and proceeding west on John Daly Boulevard until one sees a "Road Closed" sign. To get to an un- paved public parking lot, turn right on Skyline Bou- levard, and make an immediate left turn into a small road which leads to horse stables. The southernmost extent of Merced Forma- tion coastal exposures occurs northwest of Mussel Rock. In fact, the cliffs in this area contain the type section of the Merced Formation. North of Mussel Rock, one can also see the 1906 trace of the San Andreas fault. South of Mussel Rock, the Mesozoic Franciscan Complex is present. The public parking lot of Mussel Rock State Park can be reached by exiting Highway 1 on Manor Drive and following Palmetto Avenue northwest to Westline Drive. GEOLOGICAL SETTING The Merced was deposited in a small struc- tural basin which probably developed between strike-slip faults. The Merced has been informally divided into two units: a lower unit with sediments derived from local source rocks (i.e., the Franciscan complex) and an upper unit composed of sediments from the Sacramento and San Joaquin river drain- ages. The lower unit is also dominated by shelf fades while the upper one is dominated by eolian fades. The boundary between the two units has been placed at about 0.6 Ma (Sarna-Wojcicki et al., 1985). The fades represent a range of paleo-environ- ments including eolian sand dunes; alluvial sys- tems; freshwater ponds; nearshore, backshore, and foreshore settings; to inner-, mid- and outer-shelves. Maximum depth of deposition is about 100 m be- low sea level (Clifton, 1988). The Merced section are composed of a series of transgressive-regressive cycles which may reflect glacioeustatic cycles. Eighty percent of the thickness of the Merced For- mation consists of shallowing-upward, progradational sequences—many of which exhibit a marine to non-marine succession (Clifton and Hunter, 1987). Based on fossils, the cliff exposures are thought to be entirely Pleistocene in age although the lowermost sections of the Merced may include the Pliocene as well. An ashbed in the upper part of the formation has been dated at 0.40 Ma (Sarna- Wojcicki et al., 1985). The Merced Formation is overlain by the Colma Formation which is thought to have been deposited during the last interglacial highstand (Hunter et al., 1984). Page 8 1997 CalPaleo Abstracts PaleoBios 18(1) Supplement PALEONTOLOGY Both trace and body fossils are distributed throughout the Merced Formation in a number of different paleoenvironmental facies. However, finding fossils from the coastal outcrops is compli- cated by their patchy distributions and bad expo- sures due to the poorly-consolidated nature of the Merced and weathering patterns of the sea cliffs. The most conspicuous body fossils are found in current-winnowed lags or storm beds which are often composed of shell hash. The fossil material itself is fairly friable once removed from the sur- rounding matrix. Invertebrate paleontology Invertebrate trace fossils are found in a number of facies and include Macaronichnus, possi- bly made by deposit-feeding polychaetes, large bur- rows and "siphon tracks" probably made by bivalves, and firmground burrows possibly made by decapod crustaceans. Molluscan body fossils can be found in coastal embayments, shelfal, and nearshore facies. Fossil fragments are often found as winnowed accumulations of shell hash. Some remains of insects have also been recovered from facies representing freshwater pond paleoenvironments. Vertebrate paleontology In backshore facies, isolated areas of dis- rupted laminae have been interpreted as vertebrate tracks. These footprints range in size from 5 to 50 cm in diameter in depth and may have been made by canids, split-hoofed ungulates, and proboscide- ans. In addition, there are 30-cm-thick beds which appear to have undergone much deformation; these have been hypothesized to have been intensely trampled by large mammals while the sediment was still water-saturated. Some terrestrial mammal fossils—including Matnmuthus bones—have been recovered from eolian dunes, freshwater ponds, and backshore facies. REFERENCES Clifton, H. E., 1988. Sedimentologic approaches to paleobathymetry, with applications to the merced Formation of central California. Palaios, v. 3, p. 507-522. Clifton, H. E., Hunter, R. E., and Gardner, J.V., 1988. Analysis of eustatic, tectonic, and sedimento- logic influences on transgressive and regres- sive cycles in the late Cenozoic Merced For- mation, San Francisco, California. In Paola, C, and Kleinspehn, K.L. (eds.), New persectives in basin analysis, Springer-Verlag, New York, p. 109-128. Clifton, H. E., and Hunter, R. E., 1987. The Merced Formation and related beds: A mile-thick suc- cession of later Cenozoic coastal and shelf de- posits in the seacliffs of San Francisco, Califor- nia. In, Geological Society of American Cen- tennial Field Guide—Cordilleran Section, p. 257-262. Clifton, H. E., and Hunter, R. E., 1991. Depositional and other features of the Merced Formation in sea cliff exposures south of San Francisco, California. In Sloan, D., and Wagner, D.L. (eds.), Geologic excursions in northern Cali- fornia: San Francisco to the Sierra Nevada, Special Publication 109, California Division of Mines and Geology, Sacramento, p. 35-44. Hunter, R. E., Clifton, H. E., Hall, N. T., Csaszar, G., Richmond, B.M., and Chin, J.L., 1984. Pliocene and Pleistocene coastal and shelf deposits of the Merced Formation and associated beds, northwestern San Frandisco Peninsula, Cali- fornia, SEPM Field Trip Guidebook 3, p. 1-29. Sarna-Wojcicki, A.M., Meyer, C.E., Bowman, H.R., Hall, N.T., Russell, P.C., Woodward, M.J., and Slate, J.L., 1985. Correlation of the Rockland ash bed, a 400,000-year-old stratigraphic marker in northern California and western Nevada, and implications for middle Pleis- tocene paleogeography of central California, Quaternary Research, v. 23, p. 236-257. PaleoBios 18(1) Supplement 1997 CalPaleo Abstracts Page 9 1997 California Paleontology Conference Abstracts REASSESSING OXYGEN ISOTOPE VARI- ABILITY IN PLANKTONIC FORAMIN- IFERA: IMPLICATIONS FOR SEA SUR- FACE TEMPERATURE ESTIMATES Bemis, Bryan E. and Spero, Howard J., De- partment of Geology, University of Cali- fornia, Davis, CA 95616 Bijma, Jelle, Alfred-Wegener Institute of Po- lar and Marine Research, P.O. Box 120161, D-27515, Bremerhaven, Germany Lea, David W., Marine Science Institute and the Department of Geological Sciences, University of California, Santa Barbara, CA 93106. We have investigated the influence of tem- perature, light level, sea water oxygen isotopic com- position, sea water carbonate ion concentration, and sea water phosphate concentration on oxygen iso- tope values of the planktonic foraminifera Orbulina universa (symbiotic) and Globigerina bulloides (non- symbiotic). These experiments demonstrate that O. universa shells grown in high light have lower oxy- gen isotope values than low light individuals grown at the same temperatures, due to symbiont activity. In addition, elevated sea water carbonate ion con- centration exerts a non-temperature dependent, negative offset on oxygen isotopes of O. universa shells. Elevating sea water phosphate concentra- tion has no significant effect on O. universa oxygen isotope values. Equilibrium calcite predictions using empiri- cal high and low light O. universa paleotemperature equations account for >80% of the oxygen isotope variability observed in plankton tow material. The mean of these equations provides an excellent fit to the data. The oxygen isotope values of individual G. bulloides chambers are size-dependent, such that successively larger chambers in the shell whorl have higher oxygen isotope values at all temperatures studied. This produces a strong dependence of whole shell isotopes on shell size, as observed in other studies of fossil and plankton tow-collected samples. Our equations provide much more realis- tic depth habitat interpretations for this species. Other paloetemperature equations may overesti- mate temperature by ~1-2°C for symbiotic plank- tonic foraminifera, and by 3°C or more for G. bulloides data. A COMPARATIVE STUDY BETWEEN THE DROSOPHILA AND TRIBOLIUM EVEN- SKIPPED PROMOTERS AND THE EVOLU- TION OF SEGMENTATION. Blair, Adrienne, Molecular Biology Institute, UCLA, Los Angeles CA 90095 As Arthropods, both the fruit fly Drosophila and the red flour beetle Tribolium share a segmented body plan, one of the defining characteristics of the phylum. The pair-rule gene even-skipped (eve) encodes a homeodomain protein that functions as a transcriptional regulator in the segmentation hier- archy during embryogenesis. There are intriguing similarities and differences in the modes of devel- opment of these two insects before the onset of segment specification. The long-germ-band devel- opment of Drosophila is the derived condition where the entire body plan is specified in the syncytium (an environment where transcription factors are able to diffuse freely). Distantly related Tribolium has intermediate-germ-band development, a con- dition where only the gnathal and thoracic seg- ments are specified in the syncytium. The remain- ing abdominal segments form after cellularization and are added sequentially from a posterior growth zone. The developmental genetics of Drosophila have been extensively studied and provide an excellent starting point for a comparative study. In Droso- phila, eve expression is the first evidence of segmen- tation, and is seen as the simultaneous expression of seven transverse stripes along the anterior-poste- rior axis of the developing embryo. The regulatory elements of stripes 2,3+7, and to a lesser extent the autoregulatory element, have been dissected to a mechanistic level. This provides an opportunity to implement a reverse experimental approach, that is, to determine whether these regulatory elements are present and functionally similar in Tribolium. The Tribolium eve ortholog has been cloned, and molecular charaterization of sequences up- stream and downstream of the coding region is in Page 10 1997 CalPaleo Abstracts PaleoBios 18(1) Supplement progress. To date, putative promoter sequences from Tribolium are capable of driving the expres- sion of a reporter gene in Drosophila embryos in a Drosophila-]ike pattern in the dorsal mesoderm and the presumptive anal pads. More interestingly, se- quences within the second intron of Tribolium eve indicate autoregulatory function. This region is capable of driving the expression of a reporter gene in a pattern of late eve-like stripes in Drosophila embryos undergoing germ band extension. Fur- ther sequences are being tested for regulatory ele- ments capable of driving the expression of segmen- tal stripes in the early embryo. THE EVOLUTION OF DIADROMY IN NERITID GASTROPODS OF THE TROPICS Boyer, Sarah, Department of Intergrative Bi- ology, University of California, Berke- ley, CA 94720 The gastropod family Neritidae includes taxa that have adapted to many different environments, including marine, freshwater, and terrestrial habi- tats. This group first appears in rocks of Triassic age, and genera with freshwater representatives originate in the Cenozoic. The first appearance of Neritina is in the Eocene. The first appearance of Clithon is in the Pliocene, and Septaria is known only from the Recent. All three of these genera include freshwater as well as marine taxa, and this poly- phyletic distribution suggests that this habitat shift is particularly easy for animals of this group to make. The biogeography of the Neritid radiation into freshwater is tied to high oceanic islands of the Pacific Basin. The dispersal to these islands was facilitated by their diadromous life history: fresh- water Neritid larvae undergo much of their larval development in salt water. Five freshwater species of Neritids, representing the genera Neritina, Clithon, andSeptaria, occur in the streams of the Is- land of Moorea, French Polynesia, and marine rep- resentatives from these groups are numerous on the reefs of the island. This site is therefore an ideal setting in which to investigate the evolution of diadromy through comparative study of the life histories of Neritid species. In general, increased salinity promotes an increased rate of larval devel- opment in molluscs, but whether this is true in diadromous species remains to be seen. Under- standing of the ecology of freshwater and marine larvae is key to understanding the Neritids' evolu- tion of diadromy and invasion of island streams. THE MARTIAN "FOSSILS": A CASE STUDY IN SCIENTIFIC CONFIRMATION AND THE PUBLIC PURSE. Bragin, John, UCLA Center for the Study of Evolution and the Origin of Life. Los Angeles, CA 90095. The extreme vigor with which the NASA Mars Rock team — and particularly its head scientist Dr David McKay — has been on the stomp across the United States for the case that the Rock holds true fossils of immensely ancient organisms has eclipsed the many lines of counter-argument to these claims at almost all levels of the science, media and public communities. What are the claims? Under what concepts of scientific confirmation are the proponents arguing their case? How good are the "raw" observations and — even if they are good — do they support the NASA Team's conclusions about the biogenic ori- gin of the forms? How scientifically literate would a non-spe- cialist — particularly an "average" citizen — have to be to assess these conclusions, especially in de- ciding whether he or she should support and en- courage costly government projects whose focal- point is based on these claims for early Mars life? What are the implications of the need for such literacy in general science education in public schools, colleges and universities? PHYLOGENIES OF THE COLUMBELLA AND CONELLA (NEOGASTROPODA: COLUMBELLIDAE), AND IMPLICATIONS FOR THE EVOLUTION OF NEOGENE TROPICAL AMERICAN MARINE FAU- NAS. deMaintenon, Marta J., Department of Intergrative Biology, University of Cali- fornia, Berkeley, CA 94720 The closure of the Isthmus of Panama in the mid-Pliocene is one of the most accessible model systems for assessing evolutionary responses to a vicariant event followed by large scale environ- mental change. The patterns of evolution of tropical American marine faunas have been the subject of many studies, but preservational and sampling bi- ases have hampered their identification. This paper documents the patterns of diversification and ex- PaleoBios 18(1) Supplement 1997 CalPaleo Abstracts Page 11 tinction in two groups of shallow marine molluscs of the Neogene American tropics. The members of the Columbella and ConeZZagroups of theneogastropod taxon Columbellidae were assessed through the corroboration of cladistic phylogenies and the fossil record. The three major clades of the Columbella and Conella Groups show different patterns of evolution through the Neogene in the American tropics, but also share some common trends. All three clades experienced increased extinction in the Caribbean after Isthmian closure, which was not balanced by increased origination; however no major clade went entirely extinct in the Caribbean. One eastern Pa- cific group underwent an episode of diversifica- tion, but the timing of this diversification is uncer- tain. MOVING OUT OF THE DEEP SEA INTO THE INTERTIDAL: EVIDENCE FROM MULTIPLE PATELLOGASTROPOD DATASETS. Guralnick, Robert. Department of Integra- tive Biology and Museum of Paleontol- ogy. University of Calif ornia. Berkeley, CA 94720. Morphological and molecular evidence sup- ports the positon of the Patellogastropoda as the most basal gastropod clade. Although the clade is almost exclusively intertidal, it has representatives that live in deep sea habitats, including hot vents and cold seeps. Workers have argued that presence of patellogastropod taxa at vents and seeps is the result of migration with the vents down from shal- low water habitats or later immigration and coloni- zation of the vents and seeps again from shallow water habitats. Although this onshore-offshore model may be correct, it has not been tested by examining patterns of speciation. Instead, workers have tested the model by studying fossil occurences of taxonomically similar but possibly unrelated groups. I have gathered a dataset of morphological characters and taxa in order to assess the phylog- eny of the patellogastropods. The analysis includes eighteen taxa, five of which are deep sea, and eighty three characters. All the characters have been coded from primary data, representing histological infor- mation, shell microstructure data, dissection, and observations of external anatomy. The phyloge- netic hypothesis I generated does not support an onshore-offshore model, but instead the pattern of speciation suggests that taxa have migrated from the offshore to the onshore. Stratigraphic distribu- tion of the patellogastropod lineages indicates that anoxic events may be correlated with recolonization of on-shore habitats during the Cretaceous. SIZE AND SEXUAL DIMORPHISM IN SMILODON FROM RANCHO LA BREA Gust, Sherri, George C. Page Museum. Los Angeles, CA. Preliminary results of a study of population biology of Smilodon based on innominates, reveal a large range in size of individuals. Length of the innominate varies from 350mm to 290mm. How- ever, measurements traditionally thought to reflect body mass such as acetabular length and width are extremely similar across the range in length. By restricting analysis to specimens at the same onto- genetic stage, sexual dimorphism can be observed and measured. The best characters are those defin- ing the pelvic basin. Results of the dimorphism analysis also allow calculation of sex ratio in the specimens represented at Rancho La Brea. CHICO FORMATION YIELDS CLUES TO UP- PER CRETACEOUS PALEOENVIRONMENT IN CALIFORNIA Hilton, Richard P. and Patrick J. Antuzzi, Department of Geology, Sierra College, Rocklin CA 85677 Outcrops of Chico Formation at Granite Bay, Placer County, provide evidence toward a greater understanding of the Campanian marine paleoenvironment of central California. The area contains offshore fossils, as well as fossils from an intertidal environment contained in turbidites. One turbidite contains granitic clasts two meters in length that are enclosed in a coquina-like matrix. Other clasts of unweathered slates typical of the Mariposa Formation hint of a shoreline with cliffs, perhaps east of present highway 49. Finer clastic rocks under the turbidite contain numerous plant fossils, probably once waterlogged flotsam that settled to the sea bottom. These range from numerous seeds and dicotyledonous leaves to portions of fern and cycad fronds. A large stem cast is complete with frond scars, adventitious roots, prop branches and possible seeds along the trunk. Page 12 1997 CalPaleo Abstracts PaleoBios 18(1) Supplement The fauna includes numerous bivalves, gas- tropods, ammonites, baculites, a nautilus and a scaphopod. One ammonite is the first of its genus to be found on the North American Pacific coast and two other mollusks may be new species. Other invertebrates include worm tubes and arthropod burrows, two species of urchin and a crinoid. Ver- tebrates include five species of shark, a boney fish and two types of marine turtle, as well as skull fragments from the first mosasaur from the Chico. Aside from the Chico type section, this local- ity contains the most diverse array of Late Creta- ceous fossils in California. PSEUDOFOSSILS AND MICROFOSSILS - IMPORTANT DIFFERENCES House, Christopher H., Department of Earth and Space Sciences, University of Cali- fornia Los Angeles, Los Angeles, CA 90095-1567 Although megascopic fossils have been found as far back as 2.1 Ga ago, microfossils are known from sediments up to 3.465 Ga old. Microfossils are morphologically recognizable remains of ancient microorganisms. Although well preserved Prot- erozoic microfossils have remarkably detailed structures, the Archean microfossils are not as well preserved. In all of the cases though, the fossils are distinctly cellular, and are composed of ^-en- riched organic material. For example, ion micro- probe analysis shows that the 313C value for the Bitter Springs Eomycetopsis is -22±7%o and for the Gunflint Huroniospora is -31.5+6.5 %o. Ion micro- probe analysis has also indicated the presence of carbon, nitrogen, and sulfur in the fossils. Since Archean microfossils were first reported in 1923, there have been numerous examples of non-fossils that were originally interpreted as microfossils. These pseudofossils maybe mineral grains, clumps of carbonaceous material, fluid inclusions, artifacts of preparation, or modern contamination. Al- though the recent report of possible evidence of ancient life on Mars is extraordinary, it may prove to be an example of another pseudofossil. RECONSTRUCTING DINOSAUR LOCO- MOTION: PROBLEMS AND PROSPECTUS Hutchinson, John R., Department of Integra- tive Biology, University of California, Berkeley, CA 94720 Much remains to be understood about the lo- comotion of dinosaurs. Birds have often been used as functional analogs for other bipedal dinosaurs, but the question of how useful they are as func- tional analogs has seldom been addressed. Other sorts of approaches to studying dinosaur locomo- tion often suffer from critical assumption-related flaws, are rife with speculation, or lack any phylo- genetic context. I will present one example of a holistic ap- proach to studying dinosaur locomotion, empha- sizing the comparative method and cautious sensi- tivity analysis of assumptions. The specific prob- lem that I will address is the locomotion of the large nonavian theropod Tyrannosaurus rex. Did it move more like a bird, or did its bulk constrain its loco- motory abilities as in the case of an elephant? This project uses a diversity of tools and approaches to investigate a complex problem, and demonstrates both the potential and the limitations for studying functional morphology in paleontology. COMMUNITY FLORAL ASSOCIATIONS OF THE LATE MIOCENE PUENTE FORMA- TION, CHINO HILLS, CALIFORNIA Kinoshita, Glen, Department of Geological Sciences, California State Polytechnic University, Pomona, CA, 91768 The late Miocene Puente formation near Chino, CA consists of four members: the La Vida Soquel, Yorba, and Sycamore Canyon in strati- graphic order. The upper three are Mohnian and Delmontian stage and contain an abundant fossil record within the marine strata. In addition to marine fish, algae, mammals, and birds, the deposit also contains numerous terrestrial plant remains, including leaves, seeds, and wood fragments. Leaf remains are the most common type of plant fossil, consisting of over one thousand individual speci- mens recovered from the sandstone turbidites of the three members. Analysis on the generic level of the leaves indicate that there has been a degree of preferential PaleoBios 18(1) Supplement 1997 CalPaleo Abstracts Page 13 fossilization, and the basis for this bias can be seen when comparing the recovered leaf assemblages to modern flora community associations. From pre- liminary data, there is indication that at least two discrete environments can be ascertained from ge- neric-ratios of the fossil data, these being a riparian habitat with associations between Phragmites sp., Platanus sp., andSalix sp., and an upland area characterized by members oijuniperus sp., Cercocarpus sp., and Mahonia sp. These conclusions are based on comparing present day associations of modern genera and probable transport distance based on habitat with ratios of fossils gathered at sites over the three members. This study tentatively recognizes 27 floral families, 41 genera, and at least 41 species pending further identification of the assemblages. PALEOGENE FLORAS OF THE NORTH- ERN SIERRA NEVADA: TECTONIC-GEO- MORPHIC IMPLICATIONS Lawler, David A., FarWest Geoscience Foun- dation, 48 Shattuck Square, Suite 108, Berkeley, CA 94704 Howard E. Schorn, Museum of Paleontology, University of California, Berkeley, CA 94720-4780 The Ancestral Yuba fluvial system of the northern Sierra Nevada is one of the best preserved and most extensive early Tertiary fluvial systems in the world. Some thirty paleobotanical localities, the Chalk Bluffs paleoflora (s.L), are preserved in this Eocene paleodrainage system. These sites sug- gest similar depositional settings within a vast, ag- grading fluvial system that extended from sea level to upland elevations. The recently discovered sites near the present crest of the Sierras in the Soda Springs area, Placer County, represent a tributary of the Ancestral Yuba and are the easternmost and most upland sites know within the paleodrainage system. Reevaluation of the geologic context of the thirty paleofloras suggest that the paleoelevations of these paleofloras is closely correlated with paleoelevations of the coeval Ancestral Yuba flu- vial system. This increasingly detailed body of physical and biological evidence has significant tec- tonic implications for reevaluation of Sierra Ne- vada uplift models. PALEONTOLOGICAL APPLICATIONS OF CALCIUM ISOTOPIC ANALYSIS Skulan, J. L., D. J. DePaolo, T. L. Owens. De- partment of Integrative Biology and De- partment Geology, University of Cali- fornia, Berkeley, CA 94720 Mass spectrographic analyses of calcium from a variety of biological and geological sources reveal that calcium isotopes undergo significant mass dependent fractionation during biological processing. This fractionation probably exceeds that caused by abiotic processes. 44Ca/44Ca var- ies both among organisms, and among tissues in a single organism. Analyses of soft and hard tis- sues from the same organism show that soft tis- sues are isotopically heavier than mineralized tis- sues, with 44Ca/44Ca of mineralized tissue being about 0.1% lower than that or source calcium. Preferential incorporation of isotopically light cal- cium into biominerals leaves the ocean enriched in heavy calcium, and causes calcium to become isotopically lighter as it moves through food cheains. These effects create isotopic differences among possible environmental and dietary sources of calcium, and suggest that calcium iso- topes in fossils may record information about the diet, environment and taphonomy of ancient or- ganisms. COMPARATIVE GILL MORPHOLOGY OF LUCINOIDIAN BIVALVES Weber, Robin J., Department of Integrative Biology, University of California Berkeley,CA,94720-3140 There are several taxa of bivalves that use a chemoautotrophic symbiotic nutritional strategy. These include members of the families Vesicomyidae, Solemyidae, Thyasiridae, and Lucinidae, all of which are well represented in the fossil record. Among these, the Lucinioidians have enjoyed a far more extensive evolutionary radia- tion than the other groups. Lucinids also occur in more diverse habitats and over a wider range of depth, sediment type, and latitude. Solemyids, vesicomyids, and thyasirids are more restricted eco- logically, and living and fossil members of these families are more typically associated with deep- sea settings. Vesicomyids, the most narrowly re- Page 14 1997 CalPaleo Abstracts PaleoBios 18(1) Supplement stricted, are known only from deep cold seeps and hydrothermal vents. Another distinction is that lucinids are mixotrophic, capable of particulate feeding as well as deriving nutrition from their bacterial symbionts. This mixotrophy may have played an important role in the adaptive radiation of lucinids by extending their eco-space. If so, the relative importance of heterotrophy vs. chemosymbiotic autotrophy may differ among lucinid lineages, and these differences may be re- flected in morphology. TEM analysis of the gill filaments of lucinids provides fundamental information for comparative study of the gill tissues that house the symbiotic bacteria in these bivalves. The ultrastructure of these important nutritional organs can be used with general morphological characteristics to relate nu- tritional strategy with environmental parameters and to reevaluate phylogeny. MIOCENE MUDSTICKING MONSTROSI- TIES: THE TALL TALE OF TAMIOSOMA. Whittlesey, Karen Elizabeth, Department of Earth Sciences, University of Southern California, University Park, Los Ange- les, Ca 90089-0740, whittles@usc.edu The Pancho Rico Formation, a fossiliferous, fine-grained unit, represents the final incursion of marine conditions in the Salinas Valley of Califor- nia. These strata contain abundant fossil barnacles in shell beds and small reef-like buildups, includ- ing the giant (up to 30cm long) barnacle, Tamiosoma gregaria. Unlike any other barnacle, extant or fossil, Tamiosoma flourished in a muddy, diatom-domi- nated depositional regime. In response to rapid sedimentation, the barnacles grew upward with narrow, elongate bases, like rudist bivalves. The diverse communities found there are a result of the unique depositional system found in the Pancho Rico Formation. Barnacle-dominated shell beds provided hard substrates for small barnacles to settle on, however, these shells are small in com- parison to the barnacles themselves, and served only as anchors in the mud which surrounded them. These shell beds now serve to protect the large barnacles from erosion. This preservation provides a unique glimpse into shallow marine biotas of the latest Miocene. Although previous taxonomic research recog- nized most barnacles of the Pancho Rico Formation as Tamiosoma gregaria, recent work has shown that multiple barnacle species make up the reef-like structures. Previously, based on opercular plate morphology, T. gregaria was synonymized with ex- tant Balanus aquila. Based on new specimens, Tamiosoma's opercular plates appears to be signifi- cantly different than those previously described. These findings warrant reclassification of these bar- nacle taxa, and show that a diverse barnacle com- munity, not one barnacle with varying morphol- ogy, dominated the area. THE ROLE OF ENVIRONMENTAL CON- DITIONS IN DETERMINING THE TIMING AND BEHAVIOR OF BIOTIC RECOVERY FROM MASS EXTINCTIONS: AN EX- AMPLE FROM THE EARLY TRIASSIC. Woods, Adam D., Department of Earth Sci- ences, University of Southern Califor- nia, Los Angeles, CA 90089-0740 Biotic recovery from mass extinctions has re- cently become an important topic in paleobiology. Several studies have been produced which examine and/or model how faunas recover from mass ex- tinctions and how ecosystems are re-occupied. However the question of how environmental con- ditions might affect a rebound has been largely unanswered. It seems reasonable to assume that harsh environmental conditions related to the mass extinction could persist for some time after the event, affecting both the duration and direction of the recovery. One such example of where severe environ- mental conditions may have influenced the rebound from a mass extinction is the recovery from the Permian-Triassic mass extinction. The biotic recov- ery from the mass extinction is protracted, lasting the entire length of the Early Triassic. Such an extended rebound could be attributed to the sever- ity of the mass extinction, however facies data sug- gest that harsh environmental conditions should be considered as an additional cause for a lengthened recovery interval. The Union Wash Formation of east-central California was deposited along the outer shelf to slope of western North America during the late Early Triassic, and appears to accurately record oce- anic chemistry from this time. Geochemical, sedi- mentologic and paleontologic proxies suggest PaleoBios 18(1) Supplement 1997 CalPaleo Abstracts Page 15 deposition under conditions of reduced benthic oxygenation. The combination of this data with previously-published Lower Triassic facies data suggests that harsh environmental conditions, spe- cifically anoxia, did indeed have some degree of control over the Triassic recovery, and that envi- ronmental conditions should be considered when examining the dynamics of biotic recovery.