A new species of Sunosuchus from Zigong, Sichuan, China
Fu, Q.-Ming.; Ming, S.-Ying.; Peng, G.-Zhao.
Vertebrata Palasiatica. Jan; 431: 76-83
A new mesoeucrocodylian, Sunosuchus shunanensis sp. nov., was described in this paper. Its specimen was collected from the Lowder Shaximiao Formation in the famous Dashanpu Dinosaur Quarry, Zigong, Sichuan, China in 1983. This new species resembles the others of Sunosuchus in having a narrow snout, a small cranial table, a ridge along the midline of the frontal, a pair of anterior palatal fenestrae located well anterior to the suborbital fenestrae, and a strongly developed crest B on the ventral surface of the quadrate. However, it can be distinguished from all other species of Sunosuchus on the basis of the following characters: a relatively narrow and elongate snout that attains a length 3 times that of the postorbital region, a pair of well developed maxillary depressions that occupy the posterior half of the maxilla, a relatively short but wide cranial table that attains a length-width ratio of 0.65, the interfenestral region wider than the interorbital region, the lacrimal with a flange along the anterior border of the orbit, a pair of small, split-shaped infratemporal fenestrae, the squamosal lacking the thickened or grooved lateral side, a flange along the lateral margin of the basioccipital and medioventral margin of the exoccipital. In addition, this species differs from S. junggarensis in lacking a ridge-like structure and depression or fossa on the dorsal surface of the distal portion of the quadrate body, having a deep step between the main body of the pterygoid and its palatal process, and the palatine with a narrow anterior part and a broad posterior part. It differs from S . miaoi in that the frontal enters the supratemporal fenestra. It differs from S . junggarensis and S . shartegensis in lacking two or three rows of enlarged pits on the posterior dorsal surface of the frontal.