Thalassomedon Welles, 1943

Classification

Sauropterygia > Eosauropterygia > Eusauropterygia > Pistosauroidea > Plesiosauria > Plesiosauroidea > Elasmosauridae

Thalassomedon haningtoni Welles, 1943 (type and only species)

Material

Holotype Material - DMNH 1588, an almost complete skeleton and crushed skull.

Distribution

Type Locality - Graneros Shale (Lower Cenomanian), near Pritchet, northwestern Baca County, Colorado, USA.

Images

A mounted cast of the holotype of Thalassomedon in the American Museum of Natural History seen from the front, from below showing the pectoral girdle and pelvic girdle, and from the side (AMNH 29878).

	Model of Thalassomedon, including detail of the head by Hirokazu Tokugawa (used with kind permission of Hirokazu Tokugawa, see his other models at http://www2.neweb.ne.jp/wc/A-fragi)

Discussion

The holotype of Thalassomedon was discovered by R. L. Landberg in 1939 in Baca County, Colorado. In Thalassomedon the atlas-axis is short and deep, there are 62 cervical vertebrae, and there is no pectoral or pelvic bar in the adult condition (Carpenter, 1999). The species name haningtoni is sometimes wrongly spelled 'hanningtoni' (as in Carpenter 1999) and 'haringtoni' (as in the AMNH exhibit pictured above). The three dimensional skull used in the mounted skeleton exhibits of the AMNH and DMNH is a reconstruction based on the crushed holotype specimen. Carpenter (1999) synonymized Alzadosaurus with Thalassomedon.