''Thaichelys'' (meaning "Thai turtle") is a genus of extinct proterochersid stem-

turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...

from the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch a ...

Huai Hin Lat Formation of

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

. The type species is ''T. ruchae'' and it was initially classified as a species of ''

Proganochelys ''Proganochelys'' is a genus of extinct, primitive stem-turtle. ''Proganochelys'' was named by Georg Baur in 1887 as the oldest turtle in existence at the time. The name ''Proganochelys'' comes from the Greek language, Greek word ''ganos'' meani ...

''.

Discovery and naming

The first discovered remains referable to ''Thaichelys'' were discovered in 1980 along the road from Ban Huai Sanan Sai to Na Pha Song. The remains were initially described as

Testudines Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...

indet. by de Lapparent de Broin et al. (1982) before being referred to "''

''" ''ruchae'' (now ''Thaichelys ruchae'') in 1984. The specimens have since become lost, but casts exist of all but one of the specimens in the French National Museum of Natural History. In 1981, three more specimens were discovered: SM2015-1-001 (the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

) and SM2017-1-124–SM2017-1-136. They were recovered from the exposed surface limestones of the Huai Hin Lat Formation, Ban Suan Sawan Banana Farm, Si Chomphu districtLaojumpon C, Deesri U, Khamha S, Wattanapituksakul A, Lauprasert K, Suteethorn S. (2014). New vertebrate-bearing localities in the Triassic of Thailand. ''J Sci Technol MSU''. 4335–43. and were identified as belonging to a new species of ''Proganochelys'' (''P. ruchae'') by Broin (1984). In 2025, the specimens of "''Proganochelys''" ''ruchae'' were studied again and it was determined that they belonged to a new genus, which was named ''Thaichelys''.

References

{{Taxonbar, from=Q133570938 Late Triassic reptiles of Asia Prehistoric turtle genera Fossil taxa described in 2025 Testudinata