Specimens of T. brandti were collected over the last seven years in northwestern Wyoming's Bighorn Basin and represent the earliest North American species from the group of euprimates, also known as "true" primates. The fossils date to the early Eocene epoch, about 55.8 million years ago, at the same time as a 200,000-year global warming event known as the Paleocene-Eocene Thermal Maximum occurred, Bloch said. Mammals evolved to be smaller during that time, when even- and odd-toed hoofed mammals, distantly related to modern deer and horses, also first appeared in the fossil record.
"The appearance of the first modern primates in North America co-occurred with the appearance of other modern mammals such as horses, and it's all associated with a major global warming event," said co-author Stephen Chester, a Yale University doctoral student and research associate at UF. "It in part set the stage for what we see today in terms of modern mammalian biodiversity."
Less than 6 inches long, T. brandti was omnivorous, Bloch said. While archaic primates mostly had claws, some of the characteristics of modern primates include forward-facing eyes, an enlarged brain and nails on all digits.
"They are the smallest true nails known on record, whether living or fossil," said first author Ken Rose, a professor in the Center for Functional Anatomy & Evolution at Johns Hopkins University School of Medicine. "That certainly doesn't suggest nails developed with larger bodies."
Based on the age of the fossils and analyses of Teilhardina species from other parts of the world, researchers were also able to analyze the hypothesis that mammals migrated from Asia into North America. Instead, they likely passed from Asia, through Europe and into North America on high-latitude land connections.
"This research really suggests that we are looking at something extremely close [to
|Contact: Jon Bloch|
University of Florida