Amotosaurus and Pectodens

Pectodens zhenyuensis (Li et al. 2017; IVPP V18578; Anisian, Middle Triassic; 38cm in length) was originally considered to be a diapsid and a possible protorosaur. Here Pectodens nests between Macrocnemus and Langobardisaurus. Originally the interclavicle, sternum and quadratojugal were overlooked Note the large orbit, the long metarsal 5 and the perforated pubis. The elongate caudal transverse processes anchor powerful leg muscles.

unnumbered unnamed embryo (Li et al. in press) had large eyes, 24 short cervicals and 64 short caudals along with short limbs. This tritosaur was probably a sinuous swimmer, perhaps one that preferred low-light depths.

Amotosaurus rotfeldensis SMNS 50830 (Wild 1980, Fraser and Rieppel 2006) was originally considered a juvenile Tanystropheus antiquus, but Fraser and Rieppel (2006) determined that only eight cervicals were present, a shagreen of denticles covered the vomers, palatines and pterygoids, the second sacral rib was bifurcate, the tarsus was well-ossified and three distal tarsals were present. Due to the ossified tarsus they considered the small specimen an adult. Unfortunately Fraser and Rieppel (2006) reported that Langobardisaurus had 12 rather than 8 cervicals and so missed an important shared trait. Here Amotosaurus nests with Langobardisaurus and they share a longer mt 4 compared to mt 3. The scapula is much enlarged. The ventral pubis and ischium are in contact with one another, as in Cosesaurus. The mandible is ventrally concave. The posterior teeth are difficult to see, but there seems to be little indication of anything but simple compressed cone shapes present. Pedal 5.1 was relatively shorter.

Amotosaurus is featured in

Fraser NC and Rieppel O 2006. A new protorosaur (Diapsida) from the upper Bundsandstein of the Black Forest, Germany. Journal of Vertebrate Paleontology 26(4):866-871.

Li C, Fraser NC, Rieppel O, Zhao L-J and Wang L-T 2017. A new diapsid from the Middle Triassic of southern China. Journal of Paleontology.7 pp. doi: 10.1017/jpa.2017.12

Li C, Rieppel O, Fraser N C, in press. Viviparity in a Triassic marine archosauromorph reptile. Vertebrata PalAsiatica, online here.

Wild R 1980. Tanystropheus (Reptilia: Squamata) and its importance for stratigraphy. Mémoires de la Société Géologique de France, N.S. 139:201–206

Tritosauria

Drepanosauria

Amotosaurus - Pectodens