Faculty

James M. Clark
Ronald Weintraub Professor of Biology
Systematics and Paleontology of Dinosaurs and Crocodylomorpha
Lisner Hall 344 (Office)
Bell Hall 401 (Lab)

Tel. Lab: (202) 994-9210
Tel. Office: (202) 994-7144
Tel. Secretary: (202) 994-6090
Fax: (202) 994-6100
E-Mail: jclark@gwu.edu

Courses

• BISC 207 - Current Topics in Systematic Biology
• BISC 215 - Vertebrate Phylogeny
• BISC 216 - Morphological Systematics

Education

A.B., University of California, Berkeley, 1978
M.S.. University of California, Berkeley, 1985
Ph.D., University of Chicago, 1986
Post-Doctoral Work: Zoology Department, U.C. Davis (1987-1989), National Museum
of Natural History (1989-1991), American Museum of Natural History (1991-1994)

Research

My research addresses the interpretation of fossil land vertebrates (tetrapods), especially those from fossil deposits of the Age of Dinosaurs (the Mesozoic). My field work includes participation in the American Museum of Natural History-Mongolian Academy of Sciences expeditions to the Gobi Desert of Mongolia from 1991 to 2002 (at times as co-field leader), and extensive work in Mexico. My current NSF-funded field project is an exploration of the Middle to Late Jurassic Shishugou Formation of Xinjiang, China, in collaboration with Dr. Xu Xing of the Institute of Vertebrate Paleontology and Paleoanthropology, Beijing. Research projects focus upon the evolutionary relationships of birds to theropod dinosaurs, based upon the collections from the Gobi Desert of Mongolia and China, and the function of the foot of pterosaurs based upon a new specimen from the Early Jurassic of Mexico.

Click here for the latest from China

Dinosaurs and the Origin of Birds. The theropod dinosaurs and primitive birds collected by the AMNH-MAS expeditions to the Gobi Desert include numerous skeletons providing important new information on the relationships of birds to other dinosaurs. Among these are the first embryonic dinosaur skeleton from Mongolia and specimens of oviraptors sitting on nests in a bird-like position. My NSF-funded research, in collaboration with M. Norell, L. Chiappe, and P. Makovicky, focuses on the relationships among the closest relatives of birds, especially oviraptorids, dromaeosaurids, troodontids, the bizarre therizinosaurs, and the unusual basal bird Mononykus. Supported by a $3 million NSF Tree of Life grant in 2002 (along with J. Cracraft, G. Barrowclough, and S. Hackett), we are now developing an online database of theropod and bird morphological characters including images of each character.

Locomotion in Pterosaurs. An exquisite skeleton of a primitive pterosaur from Huizachal Canyon in Mexico provides important information about the capacity for walking and running in these animals. In particular, the joint at the base of the toes (the metatarsal-phalangeal joints) are nearly flat, preventing them from bending back into a posture in which the animal walked or ran on its toes, rather than on the ball of its foot. This research is in collaboration with James Hopson of the University of Chicago.

Thalattosaurs. Abundant isolated bones and articulated skulls of this obscure group of lizard-like reptiles distantly related to dinosaurs were collected in Nevada and are currently being removed from their limestone matrix in acid baths. This work is in collaboration with Hans-Dieter Sues of the Royal Ontario Museum and Nick Hotton of the National Museum of Natural History and funded by the National Geographic Society.

Phylogeny of Crocodylomorpha. My dissertation work on crocodylomorph phylogeny identified the major clades in this large group, which includes living crocodylians and a wide variety of extinct forms related more or less distantly to them. Clark (1994) presented a cladogram and data matrix for the Crocodyliformes, and Clark et al. (2000) presented an analysis of the remaining crocodylomorphs.

Phylogenetic Studies of Fossils. Fossils offer important information about evolutionary relationships, but they also are difficult to study because of they are invariably incomplete. My research explores the limitations and advantages of information from fossils, especially regarding the effect of missing data and the inference of non-morphological features of fossils.

Field Work. My field research, undertaken nearly every summer since my co-discovery of the Fruita Paleontological Area in the Late Jurassic of Colorado with George Callison in 1975, has focused on fossil vertebrates in dinosaur-age deposits (i.e., the Mesozoic). Two areas of special interest are the Cretaceous dinosaur deposits of Mongolia, as a member and co-organizer of the American Museum of Natural History-Mongolian Academy of Sciences expeditions to the Gobi Desert since 1991, and an Early Jurassic locality in the Sierra Madre Oriental of Mexico I discovered in 1982 with R. Cifelli, in Huizachal Canyon. Other field work includes expeditions to Late Triassic marine deposits of Nevada (with H.-D. Sues and N. Hotton), Early Jurassic fluvial deposits of the Glen Canyon Group in Arizona (with D. Fastovsky and K. Padian), Early Jurassic deposits in southern Arizona, Cretaceous-Tertiary boundary deposits of eastern Montana (with W. Clemens), Early Cretaceous deposits of central Mexico (with R. Hernandez and M. Montellano), Jurassic deposits of Venezuela (with M. Sanchez-Villagra), Tertiary deposits of Yemen (with I. Tattersall and P. Whybrow), and Cenozoic deposits of Vietnam (with I. Tattersall and J. Schwartz).

In 2000 I began a new field project in Middle to Late Jurassic deposits of Xinjiang, northwestern China along with Dr. Xu Xing. Organized in collaboration with the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, this project is directed towards discovering the earliest members of dinosaur lineages dominating the Cretaceous Period, including the theropod dinosaurs most closely related to birds.

Publications

Clark, J.M., and P. Ulinski. 1984 A golgi study of the anterior dorsal ventricular ridge of the Alligator, Alligator mississippiensis. Journ. Morphol. 179:153-174.

Clark, J.M. 1985 Fossil plethodontid salamanders from the latest Miocene of California. Journ. Herpetology 19(1):41-47.

Clark, J.M., and J.A. Hopson. 1985 The first mammal-like reptile from Mexico and its bearing on the phylogeny of the Tritylodontidae. Nature 315:398-400.

Benton, M. J. and J.M. Clark (alphabetical) 1988 Archosaur phylogeny and the relationships of the Crocodylia. In: The Phylogeny and Classification of the Tetrapods, Vol. 1: Amphibians, Reptiles, Birds, M. J. Benton, editor. Syst. Assoc. Spec. Vol. 35A, Clarendon Press, London.

Clark, J.M., L. Jacobs, and W. Downs. 1989 Mammal-like dentition in a Mesozoic crocodylian. Science 244:1064-1066

Norell, M.A. and J.M. Clark. 1991 A reanalysis of Bernissartia fagesii, with comments on its phylogenetic position and its bearing on the origin and diagnosis of the Eusuchia. Bulletin Institut National de Sciences Naturelles, Belgique 60:115-128.

Shaffer, H.B., J.M. Clark, and F. Kraus. 1991 When molecules and morphology clash: A phylogenetic analysis of North American ambystomatid (Caudata: Ambystomatidae) salamanders. Systematic Zoology 40:284-303.

Clark, J.M. and M. Norell. 1992 The Early Cretaceous crocodylomorph Hylaeochampsa vectiana from the Wealden of the Isle of Wight. American Museum Novitates 3032.

Perle, A., M. Norell, L. Chiappe, and J.M. Clark. 1993 Flightless bird from the Cretaceous of Mongolia. Nature 362:623-626.

Norell, M., J.M. Clark, and L.M. Chiappe. 1993 Scientific correspondence: Naming names. Nature 366:518.

Clark, J.M. and R. Hern·ndez. 1994 A new burrowing diapsid from the Jurassic of Mexico. Journal of Vertebrate Paleontology 14:180-195.

Perle A., L.M. Chiappe, Barsbold R., J.M. Clark, and M.A. Norell. 1994. Skeletal morphology of Mononykus olecranus (Theropoda: Avialae) from the Late Cretaceous of Mongolia. American Museum Novitates 3105, 29 pp.

Sues, H.-D., J.M. Clark, and F. Jenkins, Jr. 1994 A review of the Early Jurassic tetrapods from the Glen Canyon Group of the American southwest. Pp. 284-294 in: In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods, N. Fraser and H.- D. Sues (eds.), Cambridge Univ. Press.

Clark, J.M. 1994 Patterns of evolution in Mesozoic Crocodyliformes. Pp. 84-97 in: In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods, N. Fraser and H.-D. Sues (eds.), Cambridge Univ. Press.

Clark, J.M., M. Montellano, J. Hopson, R. Hern·ndez, and D. Fastovsky. 1994 An Early or Middle Jurassic tetrapod assemblage from the La Boca Formation, northeastern Mexico. Pp. 295-302 in: In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods, N. Fraser and H.-D. Sues (eds.), Cambridge Univ. Press.

Novacek, M.J., M. Norell, M.C. McKenna, and J.M. Clark. 1994 Fossils of the Flaming Cliffs. Scientific American 271(6):60-69.

Clark, J.M., Perle, A., and Norell, M. 1994 The skull of Erlicosaurus [sic] andrewsi, a Late Cretaceous "segnosaur" (Theropoda: Therizinosauridae) from Mongolia. American Museum Novitates 3115, 39pp.

Norell, M., J.M. Clark, and J.H. Hutchison 1994. The Late Cretaceous alligatoroid Brachychampsa montana: new material and putative relationships. American Museum Novitates 3116, 26pp.

Norell, M., J.M. Clark, Dashzeveg D., Barsbold R., L.M. Chiappe, A.R. Davidson, M.C. McKenna, Perle A., and M.J. Novacek. 1994 A theropod dinosaur embryo and the affinities of the Flaming Cliffs dinosaur eggs. Science 266:779-782.

Clark, J.M. 1995 An egg thief exonerated. Natural History 104(6):56-57.

Dashzeveg D., M. Novacek, M. Norell, J.M. Clark, L.M. Chiappe, A. Davidson, M.C. McKenna, L. Dingus, C. Swisher, and Perle A. 1995 Extraordinary preservation in a new vertebrate assemblage from the Late Cretaceous of Mongolia. Nature 374:446-449.

Fastovsky, D.E., J.M. Clark, N. Strater, M. Montellano, R. Hern·ndez R., and J.A. Hopson. 1995 Depositional environments of a Middle Jurassic terrestrial vertebrate assemblage, Huizachal Canyon, Mexico. Journal of Vertebrate Paleontology 15:561-575.

Tattersall, I., J.M. Clark, and P. Whybrow. 1995 Paleontological reconnaissance in Yemen. Bull. Amer. Inst. Yemeni Stud. 37:21-24

Norell, M.A., J.M. Clark, L. Chiappe, and D. Dashzeveg. 1995. A nesting dinosaur. Nature 378:774-776.

Norell, M. and J.M. Clark. 1996 Dinosaurs and their youth. Science (correspondence) 273:165-166.

Chiappe, L., M. Norell, and J.M. Clark. 1996. Phylogenetic position of Mononykus from the Upper Cretaceous of the Gobi Desert. Memoirs of the Queensland Museum 39(3):557-582.

Chiappe, L.M., M.A. Norell, and J.M. Clark. 1997. Mononykus and birds: methods and evidence. The Auk 114(2):300-302.

Clark, J.M. 1997. Crocodylia. In: The Encyclopedia of Dinosaurs, P. Currie and K. Padian (eds.). Academic Press.

Norell, M. and J.M. Clark 1997 Birds are dinosaurs. Science Spectra 8:28-34.

Norell, M., P. Makovicky, and J.M. Clark 1997 A wishbone in Velociraptor. Nature 389:447.

Clark, J.M., J.A. Hopson, R.Hernandez, D.E. Fastovsky, and M. Montellano 1998 Foot posture in a primitive pterosaur. Nature 391:886-889.

Chiappe, L., M. Norell, and J.M. Clark 1998 The skull of a relative of the stem-group bird Mononykus. Nature 392:275-278.

Reynoso, V.H. and J.M. Clark 1998 A dwarf sphenodontian from the Jurassic La Boca Formation of Mexico. Journal of Vertebrate Paleontology 18: 333-339.

Clark, J., M. Norell, and L. Chiappe 1999 An oviraptorid skeleton from the Late Cretaceous of Ukhaa Tolgod, Mongolia, preserved in an avian-like brooding position over an oviraptorid nest. American Museum Novitates 3265, 36 pp.

Clark, J., H.-D. Sues, and D. Berman 2000 A new specimen of Hesperosuchus agilis from the Upper Triassic of New Mexico and the interrelationships of basal crocodylomorph archosaurs. Journal of Vertebrate Paleontology 20(4):583-704. PDF

Norell, M.A., P. Makovicky, and J. Clark 2000. A new troodontid theropod from Ukhaa Tolgod, Mongolia. Journal of Vertebrate Paleontology 20:7-11. PDF

Norell, M.A., J. Clark, and L.M. Chiappe 2001 An embryonic oviraptorid (Dinosauria: Theropoda) from the Upper Cretaceous of Mongolia. American Museum Novitates 3315, 1-17. PDF

Norell, M.A., J. Clark, and P.J. Makovicky. 2001. Relationships among Maniraptora: problems and prospects. Pp. 49-67 in Jacques Gauthier and Lawrence F. Gall, editors. New perspectives on the origin and early evolution of birds: proceedings of the international symposium in honor of John H. Ostrom; New Haven: Peabody Mus. Nat. Hist., Yale Univ.

Chiappe, L. M. M. Norell, and J. Clark. 2001. A new skull of Gobipteryx minuta (Aves, Enantiornithes) from the Cretaceous of the Gobi Desert American Museum Novitates 3346, 1-15. PDF

Clark, J. M. , M. A. Norell, and T. Rowe 2002. Cranial anatomy of Citipati osmolskae (Theropoda, Oviraptorosauria), and a reinterpretation of the holotype of Oviraptor philoceratops. American Museum Novitates 3364, 1-24. PDF

Clark, J.M. and H.-D. Sues. 2002. Two new species of basal crocodylomorphs and the status of the Sphenosuchia. Zoological Journal of the Linnean Society 136:77-96.

Clark, J.M., M. Norell, and P. Makovicky. 2002. Cladistic approaches to the relationships of birds to other theropods. Pp. 31-64 in: "Mesozoic Birds: Above the Heads of Dinosaurs," L. Chiappe and L. Witmer, editors, University of California Press.

Makovicky, P.J., M.A. Norell, J.M. Clark, and T. Rowe. 2003. Osteology and relationships of Byronosaurus jaffei (Theropoda: Troodontidae). American Museum Novitates 3402, 32 pp. PDF

Kearney, M. and J. Clark. 2003 Problems due to missing data in phylogenetic analyses including fossils: a critical review. Journal of Vertebrate Paleontology 23: 263-274.

For reprint requests, please send an email to jclark@gwu.edu