Mamenchisaurid posterior cervical vertebra from Phu Dan Ma, Kalasin Province, Thailand, Phu Kradung Formation, Late Jurassic-Early Cretaceous. vertebra (SM KS26-4), right rib (SM KS26-2) and left rib (SM KS26-3)
An isolated posterior cervical vertebra of a sauropod discovered at Phu Dan Ma (Kalasin Province, northeastern Thailand) is the first informative postcranial specimen from the Phu Kradung Formation, a Late Jurassic to Early Cretaceous continental unit. The vertebra is referred to the family Mamenchisauridae, otherwise mainly known from China. In addition, spatulate teeth from the same formation and a mid-dorsal vertebra from the Late Jurassic Khlong Min Formation of southern Thailand are reassigned to this family. The occurrence of mamenchisaurids in the earliest Cretaceous of Thailand supports a hypothesis of geographical isolation of Central, Eastern and Southeast Asia during the Late Jurassic. It also suggests that the main changes in their dinosaur assemblages occurred during the Early Cretaceous, rather than at the Jurassic-Cretaceous boundary.
Key words: Dinosauria, Mamenchisauridae, Jurassic, Cretaceous, Thailand.
Fig. 1. Sauropod distribution in the Late Jurassic-Early Cretaceous of the Kalasin-Mukdahan region, northeastern Thailand. The formations are shown in shaded tones. A, Phu Dan Ma (KS26) in Kuchi Narai District, Kalasin Province; B, Dan Luang (MD3) in Khamcha-i District, Mukdahan Province. Both localities lie in the Jurassic-Cretaceous Phu Kradung Formation (J/Kpk); C, distribution of main groups of vertebrates in the non-marine formations of Thailand (figure courtesy of Lionel Cavin, Muséum d'histoire naturelle, Geneva).
First evidence of a mamenchisaurid dinosaur from the Late Jurassic/Early Cretaceous Phu Kradung Formation of Thailand: http://www.app.pan.pl/article/item/app20090155.html
Suteethorn, S., Le Loeuff, J., Buffetaut, E., Suteethorn, V., and Wongko, K. 201X. First evidence of a mamenchisaurid dinosaur from the Late Jurassic/Early Cretaceous Phu Kradung Formation of Thailand. Acta Palaeontologica Polonica 5X (X): xxx-xxx.
10 DOI: 10.4202/app.2009.0155