An Eocene tomistomine from peninsular Thailand

An Eocene tomistomine from peninsular Thailand


ไทย :

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English :

Skull and mandibular elements of a tomistomine crocodilian are described from the late Eocene to earlyOligocene lignite seams of Krabi, peninsular Thailand. The Thai tomistomine is a longirostrine form char-acterized by a rostrum/skull ratio of about 0.6; a mandibular symphysis reaching the level of the eleventhalveolus; a deep participation of the splenial in the symphysis to the level of the ninth alveolus; anenlarged fifth maxillary alveolus; long nasals reaching the premaxillae at the level of the fifth maxillaryalveolus but not contributing to the external nares; undivided posterior processes of premaxillae; a shortprefrontal, excluded by a longer lacrimal from the posteromedial margin of maxillae; vomers visibleon the palate. A phylogenetic analysis recovers the Thai specimen among derived tomistomines, on thestem lineage of the extant Tomistoma schlegelii, as a close ally of Maomingosuchus petrolica, a late Eocenetomistomine from southern China. The present recognition of Maomingosuchus sp. in late Eocene Thaideposits expands the distribution of Eocene tomistomines from southern China to the tropics. The originof Tomistominae in Asia is briefly discussed.