New genus of tiny, hornless deer that lived 32 million years ago discovered at Badlands National Park

Researchers have discovered a new genus of prehistoric deer that they believe existed some 32 million years ago in an area around what is now southwestern South Dakota. The deer would not have resembled anything like the ones that exist today, though. A study into a fossilized skull found at Badlands National Park, which eventually led to the novel findings, suggested that all of these deer were hornless and roughly the size of a modern household cat.

The study was carried out by a team of researchers from the national park, the American Museum of National History and California State Polytechnic University, and published recently in the Proceedings of the South Dakota Academy of Science, a journal. 

Mattison Shreero and Ed Welsh, both rangers at Badlands National Park, led the research effort. They named the newly-discovered deer santuccimeryx, or “Santucci’s ruminant,” after paleontologist Vincent Santucci, who helped shape the paleontology program at the park, the National Park Service said this week.

In a statement to the agency, Santucci said that he was “personally and professionally grateful to be associated with this important new fossil discovery,” particularly because it came from the place where he started his career as a National Park Service paleontologist almost four decades ago.

Santuccimeryx as a genus belongs to the Leptomerycidae family, which is extinct, and roamed parts of North America from about 41 million years ago to about 11 million years ago. That family are considered close relatives of mouse deer, whose appearance follows the name and which live in tropical forests in western Africa and southeastern Asia, according to the National Park Service. But certain features of this creature were unlike anything else — the skull, for one, had elements characteristic of different prehistoric animals that lived almost 10 million years apart. 

Researchers identified similarly unusual combinations when looking at dental features. That led them to identify the fossils as part of “a distinct species” within the previously unknown santuccimeryx genus.

“Genus” as a term refers to the group within which multiple species exist. For example, dogs, foxes, wolves and a number of other dog-like creatures all belong to the same genus, called canis, while humans belong to the genus Homo sapiens. 

The hornless deer fossil was discovered in 2016 at Badlands, which, like the creature itself, would be an unrecognizable landscape during the period when the deer actually lived. Geologists say the rock formations that eventually became Badlands began being deposited well before the santuccimeryx, but erosion processes that led to the park’s current appearance did not start happening until 500,000 years ago.