Three New Species of Primitive Ungulate Ancestors Identified

Thursday, August 19, 2021

Left to right: Conacodon hettingeri, Miniconus jeanninae, and Beornus honeyi. Image credit: Banana Art Studio.

Paleontologists have identified three new species of placental mammals called condylarths (archaic ungulates) from fossils found in Wyoming, the United States.

The newly-discovered archaic ungulates are Miniconus jeanninaeConacodon hettingeri, and Beornus honeyi.

These animals lived in what is now the United States between 66 and 63 million years ago (Paleocene epoch), just after the end-Cretaceous mass extinction that wiped out non-avian dinosaurs.

They belong to the condylarth family Periptychidae, which are distinguished from other condylarths by their teeth, which have swollen premolars and unusual vertical enamel ridges.

They may have been omnivores because they evolved teeth that would have allowed them to grind up plants as well as meat, however this does not rule out them being exclusively herbivores.

“When the dinosaurs went extinct, access to different foods and environments enabled mammals to flourish and diversify rapidly in their tooth anatomy and evolve larger body size,” said Dr. Madelaine Atteberry, a researcher at the University of Colorado Museum of Natural History.

“They clearly took advantage of this opportunity, as we can see from the radiation of new mammal species that took place in a relatively short amount of time following the mass extinction.”

Dr. Atteberry and Professor Jaelyn Eberle from the University of Colorado Museum of Natural History studied the teeth and lower jaw bones of 29 fossil condylarth species.

They aimed to determine the anatomical differences between the species, and used phylogenetic techniques to understand how the species are related to each other and to other early Paleocene condylarths in the western United States.

About the size of a marmot or house cat, Beornus honeyi was the largest.

Conacodon hettingeri is similar to other species of Conacodon, but differs in the morphology of its last molar.

Miniconus jeanninae is similar in size to other small, earliest Paleocene condylarths, but is distinguished by a tiny cusp on its molars called a parastylid.

“Previous studies suggest that in the first few hundred thousand years after the dinosaur extinction (what is known in North America as the early Puercan) there was relatively low mammal species diversity across the Western Interior of North America, but the discovery of three new species in the Great Divide Basin suggests rapid diversification following the extinction,” Dr. Atteberry said.

“These new periptychid condylarths make up just a small percentage of the more than 420 mammalian fossils uncovered at this site.”

“We haven’t yet fully captured the extent of mammalian diversity in the earliest Paleocene, and predict that several more new species will be described.”

The team’s paper was published in the Journal of Systematic Palaeontology.


Madelaine R. Atteberry & Jaelyn J. Eberle. New earliest Paleocene (Puercan) periptychid ‘condylarths’ from the Great Divide Basin, Wyoming, USA. Journal of Systematic Palaeontology, published online August 17, 2021; doi: 10.1080/14772019.2021.1924301