A new species of mekosuchine crocodilian from the middle Palaeogene Rundle Formation, central Queensland

Abstract

A new species of mekosuchine crocodilian is described from the middle Palaeogene Rundle Formation, near Gladstone. Kambara molnari sp. nov. is the third species of Kambara to be recognised in the Australian Palaeogene. The holotype comprises the caudal two thirds of a left mandibular ramus. Referred material includes several fragmentary osteoderms, a proximal phalanx and a procoelous vertebral corpus. Similar to K. murgonensis, when complete, the mandibular ramus of Kambara molnari had 17 dentary alveoli and 2 shallow, rostrocaudally elongate pits lateral to the articular fossa on the dorsolateral surface of the surangular. Unlike K. implexidens, the retroarticular process is 3 times longer than wide in dorsal view, and the retroarticular fossa is divided into 2 smaller fossae by a low, sagittally aligned ridge. The 10th-12th alveoli are confluent. Occlusal grooves for the reception of maxillary pseudocanines are lateral to a point midway between the 7th and 8th, and the 8th and 9th alveoli. Reception pits for maxillary teeth occur between the 12th-17th alveoli. These pits and grooves indicate a partial interlocking occlusal pattern. The partially interlocking occlusal pattern in 2 species of Kambara and an indeterminate early Palaeogene crocodilian from Runcorn, SE Queensland, as well as a sagittally aligned ridge on the retroarticular fossa in K. molnari, indicate a close taxonomic affinity between Mekosuchinae and Crocodylidae.