Systematic Palaeontology and Palaeobiogeography of Mamenchisaurid Dinosaursin Thailand

Abstract

Mamenchisauridae constitutes a diverse and widespread sauropod fauna in the Middle to Late Jurassic of East Asia. Recent studies represent the occurrence of the clade in the Southeast Asia and East Africa. The spatiotemporal distribution of the clade to the Early Cretaceous but less diverse in the Jurassic. In Thailand, there are reports of the isolated teeth of Mamenchisauridae sauropods from northeastern and the incomplete dorsal vertebra from Krabi province. Here, the 170 isolated cranial and postcranial specimens of Mamenchisauridae sauropods from the Upper Jurassic assemblage Phu Noi locality, Kalasin Province, Northeastern Thailand, which is interpret as the part of Lower Phu Kradung Formation has been study. From the description and comparison. The locality has yields at least four types of Mamenchisauridae sauropods, which correlated to the Late Jurassic Southwestern and Northwestern China taxa and one distinct taxon from the posterior skull roof and two dorsal vertebrae. Moreover, phylogenetic affinity of Phu Noi taxa is distinct from previously report Phu Dan Ma taxon from the Upper Phu Kradung locality. Other Phu Noi mamenchisaurid types are resembled to the Lower and Upper Shaximiao Formation which could be interpret that the Lower Phu Kradung Formation is the Callovian to Oxfordian in spatiotemporal age instead of Tithonian to Berriasian, which previously dating by the key Early Cretaceous palynomorph. The Shaximiao mamenchisaurids dispersed to Indochina terrane and surviving through the temporal time scale to the entire present age of Phu Kradung Formation, which related to Phu Dan Ma taxon, Upper Phu Kradung Formation, Kalasin province.

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