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Bighorn Basin, Wyoming

Basal Eocene (Wa-0) exposures northeast of Worland, Wyoming. We have concentrated on this area during the last four field seasons. These strata preserve a record of the oldest known true primates, artiodactyls, and perissodactyls, which immigrated into North America during the brief interval of global warming at the beginning of the Eocene.

Shawn Zack and Tonya Penkrot excavate a Wa-0 site in 2004.

Gina McKusick and Mercedes Gutierrez prepare dinner in the field kitchen.

Ken Rose (left) and Katrina Jones (right) survey the Bighorn Basin for fossils, July 2011.

2012 Field Crew and visitors.

2015 Field Crew

The Bighorn Basin of northern Wyoming is a geologist's paradise, with fossil-bearing sediments of nearly all ages from the Cambrian to the Oligocene. Older sediments are found along the margins of the basin and in the beautiful mountains that flank the basin (the Bighorns, Pryors, Beartooths, and Absarokas). Particularly important are the extensive exposures of Paleocene and Eocene age that cover the center of the basin, which are among the most fossiliferous continental beds of this age in the world.

For the last 40 years we have conducted field work during the summer in the seemingly inexhaustible early Eocene Willwood Formation in the southern Bighorn Basin (for many years in association with Tom Bown of the USGS). During that time we have established more than 1200 fossil localities from throughout the 700 meter-thick section that spans almost 3 million years(about 55.5 to 52.7 my ago). Our collection of more than 50,000 fossil mammals and other vertebrate fossils is catalogued at the Smithsonian Natural History Museum and the Denver Museum of Nature and Science, though much of it is housed in the Center for FAE to facilitate study. Included are about 200 species of fossil mammals, including some of the largest available samples of the earliest primates, ungulates, carnivores, and rodents.

Research focuses on several aspects of these fossils: comparative and functional anatomy, tempo and mode of evolution, systematics and relationships, origins of mammalian orders, and faunal composition and turnover. Since many early Eocene mammals were long known only or primarily from their teeth, special effort has been directed toward finding and restoring their postcranial skeletons. Study of postcranial anatomy provides clues to locomotor and associated behaviors, as well as relationships. We have collected hundreds of partial skeletons, including the oldest known skeletons of primates, artiodactyls, and carnivores. The stratigraphic density and richness of our samples makes them particularly important for addressing questions of evolutionary patterns, rates, and processes. Our research on evolving lineages of mammals has adduced evidence that many groups evolved gradually through the early Eocene in the Bighorn Basin. Amy Chew's 2005 dissertation analyzed the stratigraphic distribution of mammal species in our section and statistically demonstrated the existence of two episodes of faunal turnover during the early Eocene. Recently we completed a decade-long study of the faunal composition during the earliest Eocene (Wa-0) Paleocene-Eocene Thermal Maximum, immediately following the major turnover event at the Paleocene-Eocene boundary. Current efforts are concentrating on the relationship between climate change and faunal change at the biohorizons (the other episodes of faunal turnover) and during the latest biozone of the early Eocene. This has been a particular focus of the research of Dr. Amy Chew (now on the faculty at Brown University) who has been co-director of the project for the last several years. Some pertinent publications resulting from our Bighorn Basin research are cited elsewhere on this webpage.

Although we work hard during the week, often in temperatures that reach or exceed 120° in the sun (there is very little shade!), there's always time to relax around the campfire in the evening; and there are many opportunities for recreation on days off, including visiting museums in Worland, Cody or Thermopolis, hiking or relaxing in the mountains, or whitewater rafting through the Wind River Canyon. Yellowstone National Park is less than 3 hours away.

Part of the 2009 Wyoming field crew: L-R, Ken Rose, Katrina Jones (new FAE grad student), Jonathan Voegele, Gina McKusick Voegele (FAE PhD student), Dr. Rachel Dunn (FAE postdoc), Francois Gould (FAE PhD student). Crew members not in the photo include Ali Nabavizadeh (new FAE grad student), Katie Goodenberger (Stony Brook grad student), Chelsea Rose, and Dave Anderson.

Dr. Tom Bown guides us across a difficult drainage.

Gina and Mercedes quarrying at Jay's Pocket Quarry in the lower Willwood Formation, 2005.

Heather Ahrens overlooks the badlands, July 2011.

2013 Field Crew.

Ken Rose excavates a Coryphodon jaw.

July 2011 Wyoming Field Crew. (L-R, standing): Katrina Jones (FAE grad student), Leonie Schwermann (University of Bonn grad student), Simone Hoffmann (Stony Brook grad student), Heather Ahrens (FAE grad student). (L-R, seated): George Junne, Amy Chew (Western University; FAE alum), Ken Rose, Jennie Rose.

Western India

Searching for fossil vertebrates at Giral Lignite Mine near Barmer, Rajasthan. FAE graduate (then grad student) Jay Mussell at right.

Drs. Rose, Loyal, and Rana on camels at the Sam Sand Dunes, western Rajasthan.

Vastan Lignite Mine, east of Surat, Gujarat, February 2006.

Screen-washing at Vastan Mine; FAE grad student Gina McKusick at right.

Soft-shell (trionychid) turtle shell fragment in situ at the Vastan Mine, February 2006.

FAE grad student François Gould sacks matrix at Vastan Mine, Feb. 2008.

Rachel Dunn (FAE postdoc) and Heather Ahrens (FAE grad student) at Vastan Mine, March 2011; Annelise Folie (Royal Belgian Institute of Natural Sciences) at right.

Vastan Field Crew, 2008: Dr. Kishor Kumar, Dr. Rajendra Rana, Ken Rose, François Gould, Dr. Annelise Folie and Dr. Thierry Smith.

Little is known of the early Cenozoic land mammal fauna of India, and until recently, nothing had been found from prior to the middle Eocene. Because India has been suggested as a possible source area of some of the groups that first appear in the early Eocene, it is critical to find evidence of Paleocene and early Eocene mammals there.

With that objective in mind, we began a collaboration in 2001 with Prof. Ashok Sahni (Panjab University, Chandigarh) and Prof. Rajendra Rana (Garhwal University, Srinagar) to explore continental sediments, especially lignites, in western India for land mammals. Work focused initially on western Rajasthan, and later on lignite mines in Gujarat. Drs. Thierry Smith, Annelise Folie, and Pieter Missiaen, of the Royal Belgian Institute of Natural Sciences, Brussels, and Dr. Kishor Kumar of the Wadia Institute of Himalayan Geology, Dehradun, have since joined our research team. Our multinational team, including graduate students/postdocs from FAE, the Royal Belgian Institute, and Garhwal University, worked at the Vastan Mine in late 2004, February 2006, February 2008, March 2011, and January 2012. Our efforts have resulted in discovery of diverse assemblages of early Eocene fishes, sharks, frogs, lizards, snakes, birds, and mammals-the first early Eocene land mammals from India. Among more than 20 species recovered so far are the oldest known lagomorph and the oldest bats known from Asia, as well as primitive insectivores, primates, artiodactyls, and anthracobunids (see references below). The work has been funded by the National Geographic Society.

Resulting publications:

Dunn, R.H., K.D. Rose, R.S. Rana, K. Kumar, A. Sahni, T. Smith. 2016. New euprimate postcrania from the early Eocene of Gujarat, India, and the strepsirrhine-haplorhine divergence. J. Human Evol. 99: 25-51.

Koenigswald, W.v., K.D. Rose, L.T. Holbrook, K. Kumar, R.S. Rana, and T. Smith. 2018. Mastication and enamel structure in Cambaytherium, a perissodactyl-like ungulate from the early Eocene of India. PalZ (Paläontologische Zeitschrift) 92(4): 671-680.

Rana, R.S., K. Kumar, S.P. Zack, F. Solé, K.D. Rose, P. Missiaen, L. Singh, A. Sahni, and T. Smith. 2015. Craniodental and postcranial morphology of Indohyaenodon raoi from the early Eocene of India, and its implications for ecology, phylogeny, and biogeography of hyaenodontid mammals. J. Vert. Paleont. 35(5), e965308

Rose, K.D., R.H. Dunn, K. Kumar, J.M.G. Perry, K. Prufrock, R.S. Rana, and T. Smith. 2018. New fossils from Tadkeshwar Mine (Gujarat, India) increase primate diversity from the early Eocene Cambay Shale. J. Human Evol. 122: 93-107.

Rose, K.D., L.T. Holbrook, R.S. Rana, K. Kumar, K.E. Jones, H.E. Ahrens, P. Missiaen, A. Sahni, and T. Smith. 2014. Early Eocene fossils suggest that the mammalian order Perissodactyla originated in India. Nature Communications 5:5570 doi: 10.1038/ncomms6570

Rose, K.D., K. Kumar, R.S. Rana, A. Sahni, and T. Smith. 2013. New hypsodont tillodont (Mammalia: Tillodontia) from the early Eocene of India. J. Paleontology 87: 842-853.

Smith, T., K. Kumar, R.S. Rana, A. Folie, F. Solé, C. Noiret, T. Steeman, A. Sahni, and K.D. Rose. 2016. New early Eocene vertebrate assemblage from western India reveals a mixed fauna of European and Gondwanan affinities. Geoscience Frontiers 7: 969-1001.

Smith, T., F. Solé, P. Missiaen, R.S. Rana, K. Kumar, A. Sahni, and K.D. Rose. 2015. First early Eocene tapiroid from India and its implication for the paleobiogeographic origin of perissodactyls. Palaeovertebrata 39 (2)-e5

Zack, S., K.D. Rose, L.T. Holbrook, K. Kumar, R.S. Rana, and T. Smith. 2019. An enigmatic new ungulate-like mammal from the early Eocene of India. Papers in Palaeontology, 24 pp. doi: 10.1002/spp2.1288

Folie, A., R.S. Rana, K.D. Rose, A. Sahni, K. Kumar, L. Singh, and T. Smith 2013. Early Eocene frogs from Vastan Lignite Mine, Gujarat, India. Acta Palaeont. Polonica. 58 (3): 511-524. (view here)

Kumar, K., K.D. Rose, R.S. Rana, L. Singh, T. Smith, and A. Sahni. 2010. Early Eocene artiodactyls (Mammalia) from western India. J. Vert. Paleontol. 30(4): 1245-1274.

Mayr, G., R.S. Rana, K.D. Rose, A. Sahni, K. Kumar, and T. Smith. 2013. New specimens of the early Eocene bird Vastanavis and the interrelationships of stem group Psittaciformes. Paleontological Journal 47(11): 1-7.

Mayr, G., R.S. Rana, K.D. Rose, A. Sahni, K. Kumar, L. Singh, and T. Smith. 2010. Quercypsitta-like birds from the early Eocene of India (Aves, ?Psittaciformes). J. Vert. Paleontol. 30: 467-478.

Rage, J.-C., A. Folie, R.S. Rana, H. Singh, K.D. Rose, and T. Smith. 2008. A diverse snake fauna from the early Eocene of Vastan Lignite Mine, Gujarat, India. Acta Palaeontologica Polonica 53: 391-403.

Rana, R.S., M. Augé, A. Folie, K.D. Rose, K. Kumar, L. Singh, A. Sahni, and T. Smith. 2013. High diversity of acrodontan lizards in the Early Eocene Vastan Lignite Mine of India. Geologica Belgica 16/4: 290-301.

Rana, R.S., K. Kumar, G. Escarguel, A. Sahni, K.D. Rose, T. Smith, H. Singh, and L. Singh. 2008. An ailuravine rodent from the lower Eocene Cambay Formation at Vastan, western India, and its palaeobiogeographic implications. Acta Palaeontol. Polonica 53(1): 1-14.

Rana, R.S., H. Singh, A. Sahni, K.D. Rose, and P.K. Saraswati. 2005. Early Eocene chiropterans from a new mammalian assemblage (Vastan Lignite Mine, Gujarat, Western Peninsular Margin): oldest known bats from Asia. J. Palaeontological Soc. India 50(1): 93-100.

Rana, R.S., K. Kumar, H. Singh, and K.D. Rose. 2005. Lower vertebrates from the Late Palaeocene-Earliest Eocene Akli Formation, Giral Lignite Mine, Barmer District, western India. Current Science 89: 1606-1613.

Rana, R.S., K. Kumar, R.S. Loyal, A. Sahni, K.D. Rose, J. Mussell, H. Singh, and S.K. Kulshreshtha. 2006. Selachians from the early Eocene Kapurdi Formation (Fuller's Earth), Barmer District, Rajasthan, India. J. Geol. Soc. India 67: 509-522.

Rose, K.D., V.B. DeLeon, P. Missiaen, R.S. Rana, A. Sahni, L. Singh, and T. Smith. 2008. Early Eocene lagomorph (Mammalia) from western India and the early diversification of Lagomorpha. Proc. Royal Soc. London B 275: 1203-1208.

Rose, K.D., R.S. Rana, A. Sahni, K. Kumar, P. Missiaen, L. Singh, and T. Smith. 2009. Early Eocene Primates from Gujarat, India. J. Human Evol. 56: 366-404.

Rose, K.D., R.S. Rana, A. Sahni, K. Kumar, L. Singh, and T. Smith. 2009. First tillodont from India: Additional evidence for an early Eocene faunal connection between Europe and India? Acta Palaeont. Polonica 54(2): 351-355.

Rose, K.D., R.S. Rana, A. Sahni, and T. Smith. 2007. A new adapoid primate from the early Eocene of India. Contrib. Univ. Michigan Museum Paleont. 31(14): 379-385.

Rose, K.D., T. Smith, R.S. Rana, A. Sahni, H. Singh, P. Missiaen, and A. Folie. 2006. Early Eocene (Ypresian) continental vertebrate assemblage from India, with description of a new anthracobunid (Mammalia, Tethytheria). J. Vert. Paleont. 26: 219-225.

Sahni, A., R.S. Rana, R.S. Loyal, P.K. Saraswati, S.K. Mathur, K.D. Rose, S.K.M. Tripathi, and R. Garg. 2004. Western Margin Palaeocene-lower Eocene lignites: biostratigraphic and palaeoecological constraints. Proceedings 2nd Conference, Association Petroleum Geologists (Khajuraho, India), ONGC, Tech.Sess. III: 1-22.

Sahni, A., P.K. Saraswati, R.S. Rana, K. Kumar, H. Singh, H. Alimohammadian, N. Sahni, K.D. Rose, L. Singh, and T. Smith. 2006. Temporal constraints and depositional palaeoenvironments of the Vastan Lignite Sequence, Gujarat: analogy for the Cambay Shale hydrocarbon source rock. Indian J. Petroleum Geol. 15(1): 1-20.

Smith, T., R.S. Rana, P. Missiaen, K.D. Rose, A. Sahni, H. Singh, L. Singh. 2007. Highest diversity of earliest bats in the Early Eocene of India. Naturwissenschaften 94(12): 1003-1009.

Dr. Rose and Prof. Sahni at Giral Mine.

Dr. Rana sorts screen-washed sediment at Vastan Mine, Gujarat.

Rajasthani musicians near Sam, northwest of Barmer.

Our multinational team excavates the mammal-bearing layer at Vastan during February 2006.

Local vegetable vendor in Gujarat, India.

Excavation at Mangrol Mine, January 2013.

Rachel and Heather at the Ellora Caves in Maharashtra, March 2011.

Crew at work in Vastan Mine, March 2011: (L-R) Ken Rose, Rachel Dunn, Heather Ahrens, Kishor Kumar.

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