''Spinoaequalis'' is an extinct
genus of
diapsid reptile.
The 30 cm (1 ft) long creature, known from
fossils found in
Kansas, United States, was one of the first diapsids, along with ''
Petrolacosaurus''. It was also the first reptile to return to the water, evolving shortly after ''
Hylonomus'', the oldest confirmed reptile. ''Spinoaequalis'' was not fully aquatic, frequently returning to dry land. It probably swam using its laterally flattened, fanned tail. Its name means "symmetrical spine" referring to its deep, laterally compressed tail. ''Spinoaequalis'' has been found along with beautifully preserved marine
fish, suggesting it occasionally left fresh water streams for the sea.
''Spinoaequalis'' was described and named by Michael deBraga and Robert Reisz in 1995.
References
Carboniferous reptiles of North America
Prehistoric reptile genera
Prehistoric diapsids
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