''Emarginachelys cretacea'' is a

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

belonging to the group

Cryptodira The Cryptodira ('' el, hidden neck'') are a suborder of Testudines that includes most living tortoises and turtles. Cryptodira differ from Pleurodira (side-necked turtles) in that they lower their necks and pull the heads straight back into the ...

, known from well preserved fossils from the

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval ...

stage of the Late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...

. Its exact phylogenetic position within Cryptodira is uncertain; different authors considered it to be either the earliest described chelydrid or a fossil relative of kinosternoids.

References

Cryptodira Prehistoric turtle genera Late Cretaceous turtles of North America Hell Creek fauna Fossil taxa described in 1978 {{paleo-turtle-stub