Pakasuchus

Pakasuchus is a genus of notosuchian crocodyliform distinguished by its unusual mammal-like appearance, including mammal-like teeth that would have given the animal the ability to chew. It also had long, slender legs and a doglike nose. Pakasuchus lived approximately 105 million years ago, in the mid-Cretaceous.[1] Fossils have been found from the Rukwa Rift Basin of southwestern Tanzania, and were described in 2010 in the journal Nature.[2] The type species is P. kapilimai. Pakasuchus means "cat crocodile" (paka meaning "cat" in Kiswahili) in reference to its cat-like appearance and probable behavior.

Description
Pakasuchus was around 50 centimetres (20 in) long. Like all notosuchians, it was an active terrestrial animal. It probably hunted small prey such as insects. It had a short, broad skull somewhat similar in shape to a cat. Unlike living crocodilians, Pakasuchus had distinctive heterodont teeth that varied in shape throughout its jaws. There are large, sharp teeth near the front of the jaws, and broad molar-like teeth at the back of the mouth. While multicuspid teeth are seen in many other notosuchians such as Simosuchus and Yacarerani, they are most complex in Pakasuchus. The molar-like teeth show a level of complexity that matches that of mammals, being able to occlude, or fit with one another, and provide sharp shearing edges for slicing food.[3]

Pakasuchus also differed from modern crocodilians, and many other crocodyliforms, in the reduction of osteoderms covering the body. Small, reduced osteoderms overlie the dorsal vertebrae, but fewer in number and are not as large as those of other notosuchians. However, caudal osteoderms still covered the tail. The loss of osteoderms on the body and retention of them on the tail is unique among crocodyliforms.

Discovery
A complete skeleton of Pakasuchus was found in 2008 in southwestern Tanzania by an international research team funded by the National Science Foundation and the National Geographic Society as part of the Rukwa Rift Basin Project. Remains from six other individuals were later uncovered.[4] The specific name honors Saidi Kapilima, one of the leaders of the Rukwa Rift Basin Project and who helped in the excavation of the specimens.[5]

The most complete specimen includes a nearly complete skull. Because the jaws were closed in this specimen, some of the teeth were obscured. The describers of the specimens used X-ray computed tomography scanning, or CT scanning, to image the teeth. This provided a detailed view of the animal's dentition that could not normally be observed in the specimen.