Skull from Theriognathus microps (UCM23381), collected at Hoeksplass, Murraysburg District, South Africa on January 30, 1963 by J.W. Kitching.

University of Colorado Museum of Natural History Object of the Month!

Theriognathus microps

The use of dinosaur fossils in museum exhibitions has served to increase the public's fascination with these prehistoric creatures. However, much less attention has been given to other groups of fossilized vertebrates. Dinosaurs and other fossil vertebrates can provide paleontologists with valuable information regarding the evolution of life on earth.

Theriognathus microps was a dog-sized predator that lived in the Karoo Basin of South Africa before the Age of Dinosaurs, more than 250 million years ago (Ma). It belongs to a larger group of terrestrial vertebrates called "therapsids" (mammals and their extinct relatives). The therapsid fossil record provides one of the finest examples of an evolutionary transition.

Neither mammal nor reptile, Theriognathus displayed a mosaic of "reptilian" and "mammalian" characteristics. While it had very mammal-like canine teeth and an incipient secondary palate, it retained multiple bones in the mandible, having a typical "reptilian" jaw joint. Fossils like this are important because they give us insight into the early evolution of therapsids and the origins of mammals.

The University of Colorado Museum of Natural History's Paleontology Collection houses over 70,000 fossil vertebrates. Aside from a small collection of South African therapsids, it also maintains one of the largest collections of Tertiary (65 Ma to 1.8 Ma) Rocky Mountain vertebrates in the world including over 35,200 mammals from the Paleocene and Eocene mammals (65 Ma to 35 Ma). Other important collections include late Tertiary vertebrates of Africa and Cretaceous (145 Ma to 65 Ma) marine reptiles and fish from the Western Interior of North America.

For previous Objects of the Month, check out our Archive.