Giant tortoises have been found from the Plio-Pleistocene sediments of Tha Chang sandpits,
Nakhon Ratchasima Province, Thailand. These tortoises are represented by several individuals
and are described based on carapace, plastron, limb bones, and isolated plates. Three
different morphotypes of epiplastral projection are recognized, pertaining to different
sexes or different ontogenetic stages. Based on their large size, thick shell, single
supracaudal, well-developed epiplastral projection, gulars covering anterior part
of the entoplastron or in contact with the latter, and humeropectoral sulcus posterior
to entoplastron, these Thai giant tortoises are assigned to the genus Megalochelys.
Thai specimens show strong similarities with large tortoises from India as well as
those from Flores and Timor, and are therefore very close morphologically to Melgalochelys
atlas. Our study provides new evidence about polymorphism and additional information
about distribution of Plio-Pleistocene fossil giant tortoises in South and Southeast
Asia. (C) 2019 Elsevier Masson SAS. All rights reserved.
