- Peter Wagner
- Curator of Paleozoic Molluscs
- Phone: 202-633-1345
- Fax: 202-786-2832
- E-mail Address: wagnerpj
- Mailing Address:
PO Box 37012, MRC 121
Washington, DC 20013-7012
- Shipping Address:
National Museum of Natural History
10th & Constitution NW
Washington, DC 20560-0121
- Ph.D. Geophysical Sciences University of Chicago 1995, Thesis Title:Â "The generation and maintenance of morphologic and phylogenetic diversity among early gastropods."
- M.S. Geological Sciences Michigan State University 1990, Thesis Title:Â "Phylogenetic analysis of the Lophospiridae (Gastropoda: Pleurotomariina) of the Ordovician and Silurian."
- B.S. Geological Sciences Michigan State University 1989
- B.S. Anthropology/Zoology University of Michigan, Ann Arbor 1986
The fundamentals of my research revolve around phylogenetic relationships among Paleozoic molluscs. The majority of my work has been on Cambrian - Devonian anisostrophic gastropods, although I've started dabbling with bellerophont gastropods also. I also have worked with a more obscure and entirely extinct group, the Rostroconchia.
The primary purpose of this phylogenetic work is to provide a template for the macroevolutionary studies discussed below. However, it also has resulted in an extensive taxonomic revision of Early Paleozoic gastropods.
The main macroevolutionary issues that I have studied concern rates of morphologic evolution. I have been particularly interested in how those rates might change over time, especially after the early Paleozoic. The goal of these studies has been to test a variety of hypotheses (most proposed by Jim Valentine) about why such a disproportionate number of basic metazoan types appeared in the very early Phanerozoic. Gastropods represent one such taxon. The bulk of gastropod morphospace was produced very rapidly. Subsequent evolution in the major clades failed to produce the same range of variation even after the evolution of many more species over many tens of millions of years. When morphologic separations between ancestors and descendants were examined, a highly significant decrease over time was found. Intriguingly, the decrease focused on particular types of shell differences. Among modern snails, these types of differences are observed among taxa with very different soft anatomies. Another set of differences showed very little change in evolutionary potential over time. Among modern snails, these differences are common among close relatives and often reflect differences in specific ecology.
My early work used inferred phylogenies as models for testing various hypotheses.
I found this approach dissatisfying because it was inherently biased towards
supporting hypotheses matching the assumptions of the initial analysis. I
dabbled in using stratigraphy to test
individual nodes but this was not entirely satisfying either as it could
correct flawed initial assumptions only under particular circumstances.
This led me toward likelihood
tests. Fundamentally, I used morphologic and stratigraphic data to
test multiple hypotheses simultaneously. This is best expressed as: >L[t, C |
or (in English), the likelihood of phylogeny (t) and character evolution (C) given character data and stratigraphic data, which is equal to the probability of the data given the hypotheses. The math actually is pretty simple, although it is very different from the approaches used by molecular workers. Ultimately, I wish to test hypotheses about rates of character evolution, both among characters and over time. Also, I am interested in testing hypotheses about driven trends (i.e., the tendency for a character to evolve into a particular state). Ultimately, one can contrast
L[t1, C1 | CD, SD] with the more complicated L[t2, C2 | CD, SD]
where C2 is a hypothesis positing a greater number of different rates (over time, among characters, between character states, etc.). Different trees (t1 and t2) are used to maximize the likelihoods of the null and test hypotheses. This way, both hypotheses get their best shot. Stratigraphic data serve as an arbitrator of sorts. I currently am writing programs to implement this approach (and boy, it's tough!)
Evolutionary biologists traditionally assumed that relationships existed between basic morphologies and factors affecting evolutionary potential (i.e., rates of speciation and extinction). More recently, cladists have challenged this idea, asserting that only monophyletic groups have any biological reality. The truth of the matter is that associations between gross evolutionary patterns and morphology have not been adequately examined. My current research tests this question using Paleozoic gastropods, by examining the relationship between extinction dynamics and gross morphology (especially that associated with very basic ecologic strategies, e.g., sessile suspension feeders vs. mobile detriti-/herbi-/carnivores).
Diversity studies, phylogenetic analyses and morphospace studies all require detailed stratigraphic data. To this end, I have compiled a large number of species lists that identify the species present at particular localities. As you can see, snails are known from an awful lot of localities. The scary thing is that the fossil records of many other groups is a lot better.
The effect of distributions on sampled richness.
- Research Scientist, National Museum of Natural History, Smithsonian 10/07 - present
- Research Associate, National Museum of Natural History, Smithsonian 4/05 - 9/07
- Lecturer, University of Chicago, Committee on Evolutionary Biology 6/98 - 9/07
- Curator, Field Museum 9/96 - 9/07
- Smithsonian Postdoctoral Fellow 9/95 - 8/96
Financial Awards and Support
- Testing the generality of macroevolutionary dynamics with bellerophont molluscs ($68,221) Aug. 2002 - July 2008
- NSF Research Grant EAR-9903238 - “Evolutionary dynamics among Early- Middle Devonian gastropods” ($72,444) Aug. 1999 - July 2004
- NSF Collections Grant EAR-9728991 - "Support for the Field Museum fossil invertebrate collections ($64,620) June 1998 - July 2001
- NSF Research Grant DEB-9213977 - “Phylogenetic and morphometric analysis of Early PaleozoicÂ archaeogastropods”Â ($10,000) Oct.1992 - Sept. 1995
- Sigma Xi June 1992
- Hinds Fund, Biological Sciences Division, U. Chicago April 1992
- Geological Society of America March 1992
- Smithsonian Institution Predoctoral Fellowship April 1991
- Harper Fellowship, University of Chicago Oct. 1994 - Sept. 1995
- Pringle Fellowship, Geological Sciences Dept., M.S.U. May 1990
- Teaching/Research Assistantships (U. Chicago) Oct. 1990 - August 1995
- Teaching Assistantships (Michigan State University) April 1989 - June 1990
Honors / Awards
- Charles Schuchert Award, Paleontological Society November 2004
- Best Student Paper, American Malacological Union June 1993
- Outstanding Research Proposal, Geological Society of America June 1992
- Editor, Paleobiology (2007 - present)
- Editorial Board, Palaeontologische Zeitschrift (2005 - present)
- Science Advisory Board, National Evolutionary Synthesis Center (2005 - present)
- Lecturer, Paleobiology Database "Quantitative Paleobiology" Short Course (Phylogenetics component), 2005, 2006, 2007, 2008.
- Officer Nominations Committee, the Paleontological Society (1999- 2002)
- Advisory Board, Paleobiology Database (2000- 2005)
- Reviewer for: Paleobiology, Journal of Paleontology, Systematic Biology, Proceedings of the Royal Society of London, Evolution, Palaeontology, Science, Journal of Systematic Palaeontology, Biological Bulletin, Journal of Evolutionary Biology, Lethaia, Biological Journal of the Linnean Society, Alcheringa, Geology, Journal of Geology, National Science Foundation, National Geographic, Society of Systematic Biology Graduate Student Grants (2000), The University of Chicago Press.
- Fossil and Molecular Estimates of Divergence Times for the Tree of Life: Database and Synthesis: Sept. 2006 - Present (Todd Oakley, head: National Evolutionary Synthesis Center, Durham NC)
- Adaptive Radiations Aug. 2001 - 2004. (Jonathan Losos, head; National Center for Ecological Analysis & Synthesis, Santa Barbara CA).
- Paleobiology Database (PBDB) Project Aug. 1998 - Present (John Alroy & Charles Marshall, heads; National Center for Ecological Analysis & Synthesis, Santa Barbara CA).
- Co-chair of Taxonomy Subgroup for PBDB.
GRADUATE STUDENT COMMITTEES
- Jon Marcot (Co-Chair) (Committee on Evolutionary Biology, U. Chicago; completed 2003)
- John Finarelli (Co-Chair) (Committee on Evolutionary Biology, U. Chicago; completed 2007)
- Emily Allen (Committee on Evolutionary Biology, U. Chicago; completed 2005)
- Allison Beck (Committee on Evolutionary Biology, U. Chicago; completed 2004)
- Matthew Friedman (Committee on Evolutionary Biology, U. Chicago; completed 2009)
- Anjali Goswami (Committee on Evolutionary Biology, U. Chicago; completed 2005)
- Bjarte Hannisdal (Geophysical Sciences, U. Chicago; completed 2006)
- Annat Haber (Committee on Evolutionary Biology, U. Chicago)
- Paul Harnik (Geophysical Sciences, U. Chicago; completed 2009)
- Melanie Hopkins (Geophysical Sciences, U. Chicago)
- Christian Kammerer (Committee on Evolutionary Biology, U. Chicago; completed 2009)
- Kimberly Koverman (Geophysical Sciences, U. Chicago)
- Lee Hsiang Liow (Committee on Evolutionary Biology, U. Chicago; completed 2006)
- Virginia Miller (Committee on Evolutionary Biology, U. Chicago)
- Rebecca Price (Geophysical Sciences, U. Chicago; completed 2003)
- Tom Rothfus (Geophysical Sciences, U. Chicago; completed 2005)
- Carl Simpson (Geophysical Sciences, U. Chicago; completed 2006)
- Melinda Brady (Committee on Evolutionary Biology, U. Chicago; completed 2000)
- Robin Oâ€™Keefe (Committee on Evolutionary Biology, U. Chicago; completed 2000)
- Rudyard Sadlier (Committee on Evolutionary Biology, U. Chicago)
- Chris Sidor (Organismal Biology & Anatomy, U. Chicago; completed 2000)
- Hallie Sims (Geophysical Sciences, U. Chicago, completed 2000)
- Jeff Wilson (Anatomy, U. Chicago; completed 1999)
- Phil Gottshall (Geology, U. Cincinnati; completed 1999)
- Andrea Lofgren (Geology, U. Illinois, Chicago; completed 2000)
- Andrew Rominger (Summer 2008)
- Michael Nakagaki (Summer 2008)
- Alexei Rivera (Summer 1999)
- Kimberly Koverman (Summer 1997)
- Western Australia (Ordovician, Devonian & Carboniferous). (7/04)
- Antelope Valley Formation (Ordovician) / Ely Dolomite (Ordovician) (9/00)
- Lost Burro Formation (Devonian) / Antelope Valley Formation (Ordovician), Nevada / California (4/99)
- Lost Burro Formation (Devonian), Death Valley National Park (5/98)
- January 2007 - Present: Paleobiology Department Representative, Fellowship Committee.
- November 2007 - Present: Alternate, Paleobiology representative, Senate of Science
- November 2006: Presentation for Friends of Geology donors group.
- November 2003: "Introduction to museum research" lecture (Committee on Evolutionary Biology)
- November 2002: "Introduction to museum research" lecture (Committee on Evolutionary Biology)
- May 2001 - May 2004: Academic Affairs Information Technology Subcommittee (Chair).
- May 2001 - May 2004: Library Committee.
- January 2001 - May 2004: Information Technology Committee.
- November 2000: "Introduction to museum research" lecture (Committee on Evolutionary Biology)
- October 2000 - August 2002: Academic Affairs representative for "Kaffeklatsch" / Roundtable.
- July 2000: Presentation on FMNH / University of Chicago interactions to the Dean of Physical Sciences
- September 1999 - October 2000: Organizer, A. Watson Armour III Symposium "The history of biodiversity."
- April - December 1999: Chair, Paleobotany search committee
- May 1999: Science Olympiad judge.
- December 1998: Outside member of Zoology search committee (entomology position)
- November 1998: "Introduction to museum research" lecture (Committee on Evolutionary Biology)
- Summer 1998: Co-organizer "Summer Symposium Series."
- April 1998: Organizer A. Watson Armour III Spring Symposium "Combining molecular and paleontological data."
- February 1997: "Introduction to Invertebrate Paleontology" lecture for museum volunteers.
- November 1996: "Introduction to museum research" lecture (Committee on Evolutionary Biology)
- Nov. 1996 - August 2007: Ongoing: Maintenance and development of departmental server and online database.
- Nov. 1996 - August 2007: Maintenance and development of Geology image analysis laboratory.
Pyenson, Nicholas D., Parham, James F. and Velez-Juarbe, Jorge. 2016. The dilemma of trade samples and the importance of museum vouchers—caveats from a study on the extinction of Steller's sea cow: a comment on Crerar et al. (2014), Biology Letters, 12(2):20150149
Le Roux, Jacobus P., Achurra, Luciano, Henríquez, Álvaro, Carreño, Catalina, Rivera, Huber, Suárez, Mario E., Ishman, Scott E., Pyenson, Nicholas D. and Gutstein, Carolina S. 2016. Oroclinal bending of the Juan Fernández Ridge suggested by geohistory analysis of the Bahía Inglesa Formation, north-central Chile, Sedimentary Geology, 333:32-49
Pyenson, Nicholas D. and Vermeij, Geerat J. 2016. The rise of ocean giants: maximum body size in Cenozoic marine mammals as an indicator for productivity in the Pacific and Atlantic Oceans, Biology Letters, 12(7)
Valenzuela-Toro, Ana, Pyenson, Nicholas D., Gutstein, Carolina S. and Suárez, Mario E. 2016. A new dwarf seal from the late Neogene of South America and the evolution of pinnipeds in the southern hemisphere, Papers in Palaeontology, 2(1):101-115
Yamato, Maya, Khidas, Kamal, Pyenson, Nicholas D., Fordyce, R. Ewan and Mead, James G. 2016. Extensively remodeled, fractured cetacean tympanic bullae show that whales can survive traumatic injury to the ears, Journal of anatomy, 228(1):125-136
O'Dea, Aaron, Lessios, Harilaos A., Coates, Anthony G., Eytan, Ron I., Restrepo-Moreno, Sergio, Cione, Alberto L., Collins, Laurel S., de Queiroz, Alan, Farris, David W., Norris, Richard D., Stallard, Robert F., Woodburne, Michael O., Aguilera, Orangel, Aubry, Marie-Pierre, Berggren, William A., Budd, Ann F., Cozzuol, Mario A., Coppard, Simon E., Duque-Caro, Herman, Finnegan, Seth, Gasparini, German M., Grossman, Ethan L., Johnson, Kenneth G., Keigwin, Lloyd D., Knowlton, Nancy, et al. 2016. Formation of the Isthmus of Panama, Science Advances, 2(8)
Goldbogen, Jeremy, Shadwick, Robert, Lillie, Margo, Piscitelli, Marina, Potvin, Jean, Pyenson, Nicholas D. and Vogl, A. W. 2015. Using morphology to infer physiology: case studies on rorqual whales (Balaenopteridae), Canadian journal of zoology, 93(9):687-700
Pyenson, Nicholas D., Vélez-Juarbe, Jorge, Gutstein, Carolina S., Little, Holly, Vigil, Dioselina and O'Dea, Aaron. 2015. Isthminia panamensis, a new fossil inioid (Mammalia, Cetacea) from the Chagres Formation of Panama and the evolution of 'river dolphins' in the Americas, PeerJ, 3:1-50
Vogl, A. W., Lillie, Margo A., Piscitelli, Marina A., Goldbogen, Jeremy A., Pyenson, Nicholas D. and Shadwick, Robert E. 2015. Stretchy nerves are an essential component of the extreme feeding mechanism of rorqual whales, Current biology: CB, 25(9):R360-R361
Boersma, Alexandra T. and Pyenson, Nicholas D. 2015. Albicetus oxymycterus, a New Generic Name and Redescription of a Basal Physeteroid (Mammalia, Cetacea) from the Miocene of California, and the Evolution of Body Size in Sperm Whales, PLoS ONE, 10(12):1-32
Kelley, Neil P. and Pyenson, Nicholas D. 2015. Evolutionary innovation and ecology in marine tetrapods from the Triassic to the Anthropocene, Science, 348(6232)
Yamato, Maya and Pyenson, Nicholas D. 2015. Early development and orientation of the acoustic funnel provides insight into the evolution of sound reception pathways in cetaceans, PloS One, 10(3):1-15
Gutstein, Carolina S., Figueroa-Bravo, Constanza P., Pyenson, Nicholas D., Yury-Yañez, Roberto E., Cozzuol, Mario A. and Canals, Mauricio. 2014. High frequency echolocation, ear morphology, and the marine-freshwater transition: A comparative study of extant and extinct toothed whales, Palaeogeography, Palaeoclimatology, Palaeoecology, 400:62-74
Pyenson, Nicholas D., Kelley, Neil P. and Parham, James F. 2014. Marine tetrapod macroevolution: Physical and biological drivers on 250 Ma of invasions and evolution in ocean ecosystems, Palaeogeography, Palaeoclimatology, Palaeoecology, 400:1-8
Pyenson, Nicholas D., Gutstein, Carolina S., Parham, James F., Le Roux, Jacobus P., Chavarria, Catalina C., Little, Holly, Metallo, Adam, Rossi, Vincent, Valenzuela-Toro, Ana M., Velez-Juarbe, Jorge, Santelli, Cara M., Rogers, David R., Cozzuol, Mario A. and Suarez, Mario E. 2014. Repeated mass strandings of Miocene marine mammals from Atacama Region of Chile point to sudden death at sea, Proceedings of the Royal Society B: Biological Sciences, 281(1781)
Gutstein, Carolina S., Cozzuol, Mario Alberto and Pyenson, Nicholas D. 2014. The Antiquity of Riverine Adaptations in Iniidae (Cetacea, Odontoceti) Documented by a Humerus from the Late Miocene of the Ituzaingó Formation, Argentina, The Anatomical Record, 297(6):1096-1102
Debey, Lauren B. and Pyenson, Nicholas D. 2013. Osteological correlates and phylogenetic analysis of deep diving in living and extinct pinnipeds: What good are big eyes?, Marine Mammal Science, 29(1):48-83
Noakes, Scott E., Pyenson, Nicholas D. and McFall, Greg. 2013. Late Pleistocene gray whales (Eschrichtius robustus) offshore Georgia, U.S.A., and the antiquity of gray whale migration in the North Atlantic Ocean, Palaeogeography, Palaeoclimatology, Palaeoecology, 392:502-509
Valenzuela-Toro, Ana M., Gutstein, Carolina S., Varas-Malca, Rafael M., Suarez, Mario E. and Pyenson, Nicholas D. 2013. Pinniped Turnover in the South Pacific Ocean: New Evidence from the Plio-Pleistocene of the Atacama Desert, Chile, Journal of Vertebrate Paleontology, 33(1):216-223
Pyenson, Nicholas D. 2013. Ecology and Conservation of the Sirenia: Dugongs and Manatees by Helene Marsh, Thomas J. O'Shea, and John E. Reynolds, The Quarterly review of biology, 88(1):42-43
Pyenson, Nicholas D., Goldbogen, Jeremy A. and Shadwick, Robert E. 2013. Mandible allometry in extant and fossil Balaenopteridae (Cetacea: Mammalia): the largest vertebrate skeletal element and its role in rorqual lunge feeding, Biological Journal of the Linnean Society, 108(3):586-599
Shadwick, Robert E., Goldbogen, Jeremy A., Potvin, Jean, Pyenson, Nicholas D. and Vogl, Wayne. 2013. Novel muscle and connective tissue design enables high extensibility and controls engulfment volume in lunge-feeding rorqual whales, Journal of experimental biology, 216:2691-2701
Goldbogen, Jeremy A., Calambokidis, John, Croll, Donald A., McKenna, Megan F., Olseson, Erin, Potvin, Jean, Pyenson, Nicholas D., Schorr, Greg, Shadwick, Robert E. and Tershy, Bernie R. 2012. Scaling of lunge feeding performance in rorqual whales: mass-specific energy expenditure increases with body size and progressively limits diving capacity, Functional Ecology, 26(1):216-226
Velez-Juarbe, Jorge, Domning, Daryl P. and Pyenson, Nicholas D. 2012. Iterative Evolution of Sympatric Seacow (Dugongidae, Sirenia) Assemblages during the Past ~26 Million Years, PLoS ONE, 7(2):1-8
Vélez-Juarbe, Jorge and Pyenson, Nicholas D. 2012. Bohaskaia monodontoides, a new monodontid (Cetacea, Odontoceti, Delphinoidea) from the Pliocene of the western North Atlantic Ocean, Journal of Vertebrate Paleontology, 32(2):476-484
Pyenson, Nicholas D., Goldbogen, Jeremy A., Vogl, A. Wayne, Szathmary, Gabor, Drake, Richard L. and Shadwick, Robert E. 2012. Discovery of a sensory organ that coordinates lunge feeding in rorqual whales, Nature, 485(7399):498-501
Goldbogen, J. A., Calambokidis, J., Oleson, E., Potvin, J., Pyenson, Nicholas D., Schorr, G. and Shadwick, R. E. 2011. Mechanics, hydrodynamics and energetics of blue whale lunge feeding: efficiency dependence on krill density, Journal of Experimental Biology, 214(1):131-146
Pyenson, Nicholas D. 2011. The high fidelity of the cetacean stranding record: insights into measuring diversity by integrating taphonomy and macroecology, Proceedings of the Royal Society B: Biological Sciences, 278(1724):3608-3616
Pyenson, Nicholas D. and Lindberg, David R. 2011. What Happened to Gray Whales during the Pleistocene? The Ecological Impact of Sea-Level Change on Benthic Feeding Areas in the North Pacific Ocean, PLoS ONE, 6(7):1-14
Uhen, Mark D., Pyenson, Nicholas D., Devries, Thomas J., Urbina, Mario and Renne, Paul R. 2011. New Middle Eocene Whales from the Pisco Basin of Peru, Journal of Paleontology, 85(5):955-969
Pyenson, Nicholas D. and Sponberg, Simon N. 2011. Reconstructing body size in extinct crown Cetacea (Neoceti) using allometry, phylogenetic methods and tests from the fossil record, Journal of Mammalian Evolution, 18(4):269-288
McKenna, Megan F., Cranford, Ted W., Berta, Annalisa and Pyenson, Nicholas D. 2011. Morphology of the odontocete melon and its implications for acoustic function, Marine Mammal Science, 28(4):690-713
Parham, James F. and Pyenson, Nicholas D. 2010. New Sea Turtle from the Miocene of Peru and the Iterative Evolution of Feeding Ecomorphologies since the Cretaceous, Journal of Paleontology, 84(2):231-247
Pyenson, Nicholas D., Irmis, Randall B. and Lipps, Jere H. 2010. Comment on "Climate, Critters, and Cetaceans: Cenozoic Drivers of the Evolution of Modern Whales", Science, 330(6001):178
Pyenson, Nicholas D. 2010. Carcasses on the coastline: measuring the ecological fidelity of the cetacean stranding record in eastern North Pacific Ocean, Paleobiology, 36(3):453-480
Uhen, M. D. and Pyenson, Nicholas D. 2007. Diversity estimates, biases, and historiographic effects: Resolving cetacean diversity in the tertiary, Palaeontologia Electronica, 10(2):11A-11A
Presentations at Invited Symposia
Darwin 2009 (SUNY, 11/09)
Testing Macroevolutionary Hypotheses of Diversification: Approaches and Perspectives (Society of Integrative and Comparative Biology Annual Meeting, San Antonio 1/08)
Perfect phylogeny and Other Problems: Compatibility Methods in Systematics (Biennieal Conference of the Systematics Association, Cardiff, 8/05)
Molluscan Phylogeny Symposium (World Congress of Malacology, Perth 7/04)
The Study of Sequences in Natural Sciences (Society of Integrative and Comparative Biology Annual Meeting, New Orleans 1/04)
Approaches to Reconstructing Phylogeny (Lyell Meetings, London, 6/02)
Major Evolutionary Radiations (Society of Systematic Biology Meetings, 6/00).
Beyond Phylogeny Reconstruction: Tree-Based Analyses in Paleontology (Geological Society of America, 10/99)
Bridging Temporal Scales in Malacology: Uniting the Living and the Dead (World Congress of Malacology, 7/98)
Stratigraphy and Phylogeny (Society of Vertebrate Paleontology, 9/97)
Traditional versus Phylogenetic Classifications in MalacologyÂ (American Malacological Union, 6/97)
Morphospace Concepts in Paleobiology (North American Paleontolological Convention, 6/96)
Molluscan Speciation (American Malacological Union, 6/93)
Speciation and the Fossil Record (Geological Society of America, 10/92)
Phylogeny and Classification of GastropodsÂ (American Malacological Union, 8/92)
Compatibility: some new uses for an old metric.Â (U. Cincinnati, 4/08).
Relative Abundance Distributions in the fossil record and their implications for major extinction events (U. New York, Buffalo, 4/07)
Relative Abundance Distributions in the fossil record and their implications for major extinction events (Cambridge University, 1/07)
Likelihood tests of macroevolutionary scenarios: examples with gastropods (Smithsonian, 6/04)
Relative abundance distributions and sampled richness (NCEAS, Santa Barbara, 1/04)
Hypothesis testing with likelihood: general relationships and speciation modes (S.U.N.Y. 12/03)
Likelihood tests of general phylogenetic hypotheses: an example with bellerophont molluscs (U. Leipzig. 3/03)
They meant to do that: dissecting patterns of gross convergence among early gastropods (U. Chicago, 2/02).
Effects of species distribution curves on sampled richness (U. New Mexico, 10/01).Â
Phylogeny likelihood given morphologic data (U. Chicago, 2/98).
Biases in diversity patterns implied by model phylogenies (U. Illinois, Chicago, 2/97; U. Arizona, 4/97).
Decreasing rates of morphologic evolution among early gastropods (U. C., Berkeley, 11/94).Â