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Randy Irmis
Padian Lab

Randy Irmis


Phone: (510) 643-2109

Research: Randy is interested in several questions, including the biogeography and ecology of the earliest dinosaurs. "Basically, dinosaurs were rare in the Triassic and exploded at the beginning of the Jurassic Period. Why is this? I'm also curious about the Triassic Period because that's when most major modern vertebrate groups evolved. It was a time of real experimentation. To answer all of these questions, we need a good understanding of these organisms' relationships, which is what I'm focusing on now."

Why UCMP? "UCMP has the best Triassic collection in the U.S. I also wanted to work with Kevin Padian, who has been involved with many of these Triassic questions. Finally, as a student with a geology background, I felt I needed a good grounding in biology as well."


Irmis, R.B., M.B. Goodwin, and G.P. Wilson. 2014. Early Mesozoic vertebrate assemblages from Ethiopia and their significance for Gondwanan biogeography. 4th International Palaeontological Congress. Programme and abstracts Mendoza, Argentina.

Goodwin, M.B., R. Irmis, G. P. Wilson, B. Atnafu. 2013. Non-marine Mesozoic ecosystems of northeastern Africa: New insights from the northwest plateau of Ethiopia. Geological Society of America Abstracts with Programs, Vol. 45, No. 7:187-2.   Read it

Lee, A.H., K. Padian, M.T. Taylor, M.J. Wedel, R.B. Irmis, and S. Werning. 2010. The universal temperature dependence model fails to predict body temperatures of mammals and dinosaurs. Society for Integrative and Comparative Biology 2010 Annual Meeting: abstract 98.7.

Pyenson, N.D., R.B. Irmis, and J.H. Lipps. 2010. Comment on "Climate, Critters, and Cetaceans: Cenozoic Drivers of the Evolution of Modern Whales." Science, 330: 178-a.

Pyenson, N.D., R.B. Irmis, J.H. Lipps, L.B. Barnes, E.D. Mitchell, Jr., and S.A. McLeod. 2009. The origin of a widespread marine bonebed deposited during the middle Miocene Climatic Optimum. Geology 37:519-522.

Irmis, R.B., and F. Knoll. 2008. New ornithischian dinosaur material from the Lower Jurassic Lufeng Formation of China. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 247:117-128  Read it

Parham, J.F., and R.B. Irmis. 2008. Caveats on the use of fossil calibrations for molecular dating. American Naturalist. 171(1):132-136.  Read it

Parker, W.G., M.R. Stocker, and R.B. Irmis. 2008. A new desmatosuchine aetosaur (Archosauria: Pseudosuchia) from the Upper Triassic Tecovas Formation (Dockum Group) of Texas. Journal of Vertebrate Paleontology. 28(3):692-701.  Read it

Irmis, R. B., N. D. Pyenson, and J. H. Lipps. 2007. Formation of marine bonbeds: insights from the Middle Miocene Sharktooth Hill bonebed of California. Journal of Vertebrate Paleontology 27(3 Suppl.): 94A.

Irmis, R.B. 2007. Axial skeleton ontogeny in the Parasuchia (Archosauria: Pseudosuchia) and its implications for ontogenetic determination in archosaurs. Journal of Vertebrate Paleontology 27(2):350-361.

Irmis, R.B. 2007. The Sauropods: Evolution and Paleobiology. Journal of Vertebrate Paleontology. 27(3):776.  Read it

Irmis, R.B., Nesbitt, S.J., Padian, K., Smith, N.D., Turner, A.H., Woody, D., and Downs, A. 2007. A Late Triassic Dinosauromorph Assemblage from New Mexico and the Rise of Dinosaurs. Science 317:358-361. (DOI: 10.1126/science.1143325)  Read it

Irmis, R.B., W.G. Parker, S.J. Nesbitt, and J. Liu. 2007. Early ornithischian dinosaurs: the Triassic record. Historical Biology 19(1):3-22.  Read it

Nesbitt, S.J., R.B. Irmis, and W.G. Parker. 2007. A critical reevaluation of the Late Triassic dinosaur taxa of North America. Journal of Systematic Palaeontology 5(2):209-243.  Read it

Pyenson, N. D., R. B. Irmis, and J. H. Lipps. 2007. Formation and taphonomy of the sharktooth hill bonebed, a unique accumulation from the Mid-Miocene of California. Geological Society of America Abstracts with Programs, 39(6): 398.

Irmis, R.B. 2006. The Dinosauria, 2nd Edition. Journal of Vertebrate Paleontology 26(1):232.  Read it

Irmis, R.B., and D.K. Elliott. 2006. Taphonomy of a Middle Pennsylvanian marine vertebrate assemblage and an actualistic model for marine abrasion of teeth. Palaios 21(5):466-479.  Read it

Parker, W.G., and R.B. Irmis. 2006. A new species of the Late Triassic phytosaur Pseudopalatus (Archosauria: Pseudosuchia) from Petrified Forest National Park, Arizona. Museum of Northern Arizona Bulletin 62:126-143.  Read it

Parker, W.G., R.B. Irmis, and S.J. Nesbitt. 2006. Review of the Late Triassic dinosaur record from Petrified Forest National Park, Arizona. Museum of Northern Arizona Bulletin 62:160-161.  Read it

Fraser, N.C., R.B. Irmis, and D.K. Elliott. 2005. A procolophonid (Parareptilia) from the Owl Rock Member, Chinle Formation of Utah, USA. Palaeontologia Electronica 8(1):13A. 7 pp.  Read it

Irmis, R.B. 2005. A review of the vertebrate fauna of the Lower Jurassic Navajo Sandstone in Arizona. Mesa Southwest Museum Bulletin 11:55-71.  Read it

Irmis, R.B. 2005. The vertebrate fauna of the Upper Triassic Chinle Formation in northern Arizona. Pp. 63-88 in S.J. Nesbitt, W.G. Parker, and R.B. Irmis (eds.), Guidebook to the Triassic formations of the Colorado Plateau in northern Arizona: Geology, Paleontology, and History. Mesa Southwest Museum Bulletin 9.  Read it

Irmis, R.B., and W.G. Parker. 2005. Unusual tetrapod teeth from the Upper Triassic Chinle Formation, Arizona. Canadian Journal of Earth Sciences 42(7):1339-1345.  Read it

Nesbitt, S.J., R.B. Irmis, S.G. Lucas, and A.P. Hunt. 2005. A giant crocodylomorph from the Upper Triassic of New Mexico. Paläontologische Zeitschrift 79(4):471-478.

Nesbitt, S.J., W.G. Parker, and R.B. Irmis (eds.). 2005. Guidebook to the Triassic formations of the Colorado Plateau in northern Arizona: geology, paleontology, and history. Mesa Southwest Museum Bulletin 9.

Parker, W.G., and R.B. Irmis. 2005. Advances in vertebrate paleontology based on new material from Petrified Forest National Park, Arizona. New Mexico Museum of Natural History & Science Bulletin 29:45-58.  Read it

Parker, W.G., R.B. Irmis, S.J. Nesbitt, J.W. Martz, and L.S. Browne. 2005. The Late Triassic pseudosuchian Revueltosaurus callenderi and its implications for the diversity of early ornithischian dinosaurs. Proceedings of the Royal Society of London, Biological Sciences 272:963-969.  Read it