CLEVELAND, Ohio – Researchers from Case Western Reserve University and two other schools have discovered something new in the prehistoric past.
With their 13 million-year-old fossil, they have identified two previously unknown ungulate species from a place in Bolivia.
The animals, called Theosodon arozquetai and Llullataruca sockeyi, resemble small moose or deer in the reproduction of an artist. Their closest living relatives would be horses and rhinos that broke apart on different evolutionary paths 60 million years ago.
Now extinct, they disappeared about 12,000 years ago, said Darin Croft, a biology professor at CWRU, the co-leader was the expeditions that have recovered the fossils.
"People have undoubtedly seen the last members of this group," he said in a telephone interview. "We just missed her, it's a little crazy."
The findings published in the June issue of the Journal of Vertebrae Paleontology are important not only because they document two species previously unknown to science, but also because they come from the northern, tropical latitudes of South America. This half of the continent has a rich variety of living mammals, but is a difficult place to find fossils.
"The study of fossils from regions like Bolivia, where few others have looked, has allowed us to discover and describe a myriad of new species that alter our views on the history of mammals in South America," said Croft, who as one of the world's leading researchers in neotropical paleontology, the study of prehistoric mammals in South America, applies.
Because South America was geographically isolated for most of them Over the past 66 million years, the fossil record has been a perfect place to study issues such as mammalian adaptation, diversification and community ecology.
The magazine's lead author was one of Croft's former students. CWRU graduate Andrew McGrath, who is now studying at the University of California-Santa Barbara. Also collaborated with Federico Anaya of Bolivia's Universidad Autonoma Tomas Frias.
The body fossils that were used in identifying the new species skulls, limbs, jaws and teeth have been collected in several expeditions over a period of years, Croft said. Their dramatically different size of the upper limbs was the first indication that they were two types.