Thalassomedon
The holotype of Thalassomedon was discovered by R. L. Landberg in 1939 in Baca County, Colorado. Thalassomedon has a short and deep atlas-axis and 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) or …