Cynodont Probainognathus Jenseni Skull

Probainognathus Jenseni was a carnivorous mammal-like reptile from the family Chiniquodontidae, and is the first animal to exhibit mammal-like features. Approximately the size of a large house cat, this animal lived in South America during the Middle and Upper Triassic, approximately 247-200 million years ago. Probainognathus Jenseni is part of a group of cynodonts that first began to exhibit specialized teeth, jaw structure, and musculature toward a mammalian pattern.

Specifically in jaw articulation, Probainognathus Jenseni exhibits both reptilian and mammalian characteristics with the jaw articulating between the articular and quadrate bones and between the dentary and squamosal bones. This fossil is an excellent example of the transition between ancestral reptiles and mammals.

This beautiful, 2-part replica skull specimen was sculpted by Glenn T. Drewes, instructor of biology at San Bernardino Valley College in California.