The Mamenchisaurids are a group of Sauropod dinosaurs known from the Late Jurassic and Early Cretaceous of China. Their taxonomy is not well understood, but they are distinctive in a number of ways from Sauropods in other parts of the world, which (along with studies on other groups) is taken as evidence that China was separated from other land-masses during this time.
In a forthcoming paper on the journal Acta Palaeontologica Polonica a team of scientists lead by Suravech Suteethorn of the Department of Biology at Mahasarakham University describe the discovery of remains attributed to a Mamenchisaurid in Kuchi Narai District in Northeastern Thailand.
The remains comprise a single, damaged vertebrae and a number of teeth from a channel conglomerate in the Phu Kradung Formation of Phu Dan Ma. This conglomerate is likely to be the result of a flash flood in a river system, and the fossils have probably been reworked, making it hard to assess their exact age; Suteethorn et al. describe the remains as Late Jurassic to Early Cretaceous in age. The fragmentary nature of the specimens makes exact classification hard, so they have not been assigned to a specific species, nevertheless vertebrae are distinctive in Sauropod Dinosaurs, so the there is some justification in assigning the remains to a Mamenchisaurid.
The vertebrae of the Phu Dan Ma Sauropod. (A) Anterior view. (B) Posterior view. (C) Dorsal view. (D) Left lateral view. (E) Right lateral view. (F) Close-up view of neural spine showing attachment scar for interspinal elastic ligament. (G) close up view of articular condyle showing a cancellous internal structure. From Suteethorn et al. (2012).
While this find is not of great palaeotological significance; it is unlikely to shed light on the lifestyle of Mamenchisaurid Dinosaurs, nor is it able to improve our knowledge of when they lived, since it is not clear when this specimen was alive, it does have considerable geographical significance. To date Mamenchisaurids are have been recorded only from China, so it this find implies that Thailand was attached to China during the Late Jurassic/Early Cretaceous.
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