Research

Richard S. White

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(Rich is 3rd from left)


Current Research


Capybara from Terapa, Sonora and the biogeography of North American fossil capybaras

With my colleagues Jim Mead, Gary Morgan and Nick Czaplewski, I am currently working on describing the fossil capybara specimens from the site of San Clemente de Terapa, on the Rio Moctezuma in Sonora, Mexico. Capybaras are relatively common at the site, with more than 30 specimens identified. Recently, Jim Mead, Sandy Swift and I travelled to San Diego, where we examined a spectacular capybara skull from a lake deposit in San Diego County, as well as spent time at the San Diego Zoo watching and photographing their group of 9 capybaras.

The capybara is the world's largest living rodent, which can reach a weight of 150 pounds or more. Many fossil capybara are even larger, as was the capybara from Terapa. Modern capybara are at least partly amphibious, and eat lake, swamp and marsh vegetation, as well as grazing on dry land.

Capybaras are known in temperate North America in the Blancan, Irvingtonian and Rancholabrean - that is, for most of the last 3 million years. Our studies will help illuminate the factors which allowed capybaras to extend from their ancestral home in South America into Central America, and ultimately into the southern United States.

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Photos courtesy of Sandy L. Swift


111 Ranch, Safford, Arizona

Survey and Inventory of Late Pliocene sediments have yielded abundant remains of fossil herps, birds and mammals which lived about 2.32 million years ago. I am studying several of the groups of animals recovered, including deer, antelope (pronghorn) and carnivores. The carnivores are being studied jointly with Greg McDonald (National Park Service).

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Click on the picture for a larger version


Capromeryx

Revision of the genus Capromeryx, an extinct 4-horned pronghorn. Remains of this animal have been found in Arizona, Texas, New Mexico, Nebraska, California and Sonora, Baja California, Chihuahua and Southern Mexico. Eight or more species have been described; Jan Saysette and I are revising the genus, and reducing the number of species to three species: an Early Blancan form, a Blancan/Irvingtonian form and an Irvingtonian/Rancholabrean form.


Stockoceros

Large samples of the extinct 4-horned pronghorn Stockoceros, have been described from San Josecito cave in Mexico and from Papago Springs Cave in southern Arizona. The two forms, S. conklingi from Mexico and S. onusrosagris from Arizona, have never been directly compared. I have measured all available specimens from both populations; preliminary results suggest that they are nearly the same size, with the northern population being just slightly larger than the more southern population.

The question of whether female Stockoceros had horns has been the subject of considerable speculation. It now appears, based on a beautifully preserved female skull from Musk Ox Cave in New Mexico, that females had greatly reduced horncores, even smaller than those of female Antilocapra. Why this hasn't been noticed in the past may be a function of preservation and collecting bias.


Ceratomeryx from Idaho

Phil Gensler from Hagerman Fossil Beds National Monument and I are currently redescribing the material of Ceratomeryx in the U.S.N.M. and some isolated elements in the HAFO collections and the University of Michigan. We should have something interesting to say about this material in the near future, based especially on the nearly complete skull Gazin found with the type specimen.


Deer from El Golfo, Sonora, Mexico

El Golfo is an Irvingtonian locality at the head of the Gulf of California. Fossils are found in deltaic sediments of the ancestral Colorado River. I am describing the many specimens of fossil deer which have been found there by Chris Shaw (Page Museum) and Fred Croxen (Arizona Western College, Yuma) and their field crews. At this time, it appears that white-tail deer are defintely present, mule deer may be present, and that there is at least one other larger cervid species in the fauna (Navahoceros?)

Keving Moodie

Keving Moodie, then at the University of Arizona, standing over a complete shell of the giant tortoise Hesperotestudo found by Richard White. This is the only complete shell ever found at El Golfo.

Fred Croxen

Fred Croxen from Arizona Western College and Robert Predmore in the field at El Golfo.

A lower jaw of the deer (Odocoileus)

Lower jaw of the deer (Odocoileus). Photo by D. Sussman, courtesy F. Croxen

The El Golfo Crew in 2002

The El Golfo Crew in 2002 in at the El Capitan Cantina in the Village of El Golfo de Santa Clara.

Biosphere Research Station in Mexico

The Mexican Government maintains a Biosphere Research Station which is located right in the middle of the fossil bearing exposures.

Click on the picture for a larger version

Also see http://www.tarpits.org/


Blancan Camelops

Working with Mary Thompson (Idaho Museum of Natural History) I am currently describing a skeleton of the camel Camelops traviswhitei which was recovered by Ted Galusha of the American Museum of Natural History in 1938. This specimen includes a beautifully preserved skull and jaws. We are comparing this specimen to other reported occurrences of Camelops from the Blancan, including a skull from Hagerman, Idaho.

Blancan Camelops Skull (Side)

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Also see:
Hagerman Fossil Beds National Monument
Idaho Museum of Natural History


Paleo Deer Hunter

(C) Ray Troll


R. S. WHITE BIBLIOGRAPHY