''Proterogyrinus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of early

tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct t ...

s from the order

Embolomeri Embolomeri is an order of tetrapods or stem-tetrapods, possibly members of Reptiliomorpha. Embolomeres first evolved in the Early Carboniferous ( Mississippian) Period and were the largest and most successful predatory tetrapods of the Late Carbon ...

. Fossil remains of ''Proterogyrinus'' have been found in Scotland, UK, and

West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the ...

, United States, and date back to the Serpukhovian (mid-

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferou ...

period), which is from about 331 to 323 million years ago. The genus was originally named by renowned vertebrate paleontologist

Alfred Sherwood Romer Alfred Sherwood Romer (December 28, 1894 – November 5, 1973) was an American paleontologist and biologist and a specialist in vertebrate evolution. Biography Alfred Romer was born in White Plains, New York, the son of Harry Houston Romer an ...

in 1970. A comprehensive redescription was later published by Canadian paleontologist Robert Holmes in 1984. The generic name "''Proterogyrinus''" is

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

for "earlier wanderer" or "earlier

tadpole A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found ...

". This name was chosen by Romer in keeping with a trend of naming long-bodied early tetrapods (such as ''

Eogyrinus ''Pholiderpeton'' (from el, φολῐ́δος , 'horny scale' and el, ἑρπετόν , 'creeping thing') is an extinct genus of embolomere amphibian which lived in the Late Carboniferous period (Bashkirian) of England. The genus was first nam ...

'' and ''

Crassigyrinus ''Crassigyrinus'' (from la, crassus, 'thick' and el, γυρίνος el, gyrínos, 'tadpole') is an extinct genus of carnivorous stem tetrapod from the Early Carboniferous Limestone Coal Group of Scotland and possibly Greer, West Virginia. Th ...

'') with the suffix "-''gyrinus''". Romer hesitated from designating ''Proterogyrinus'' as a true embolomere, because its intercentra (the forward portion of each vertebra) were smaller than its pleurocentra (the rear portion). He used the group

Anthracosauria Anthracosauria is an order of extinct reptile-like amphibians (in the broad sense) that flourished during the Carboniferous and early Permian periods, although precisely which species are included depends on one's definition of the taxon. "Anthra ...

to encompass embolomeres and their close relatives such as ''Proterogyrinus''. However, other sources prefer a wider definition of Embolomeri similar in usage to Romer's Anthracosauria, thus counting ''Proterogyrinus'' as an embolomere.

Description

In most respects ''Proterogyrinus'' resembled other embolomeres such as '' Archeria'', with a moderately elongated skull that was taller than that of other early tetrapods such as colosteids and

temnospondyls Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carbo ...

. Members of the genus had strong limbs with several fully-

ossified Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in t ...

ankle and wrist bones. This would have given ''Proterogyrinus'' the ability to walk and hunt on land. However, the presence of lateral line grooves and

otic notch Otic notches are invaginations in the posterior margin of the skull roof, one behind each orbit. Otic notches are one of the features lost in the evolution of amniotes from their tetrapod ancestors. The notches have been interpreted as part of an ...

es which likely held spiracles show that they were probably more well-adapted for the water. The tail was long and tall, and was likely a powerful method of locomotion. The eyes were positioned high on the skull, supporting the idea that ''Proterogyrinus'' had an active lifestyle near the surface of the water.

References

{{Taxonbar, from=Q134526 Extinct animals of North America Embolomeres Carboniferous reptiliomorphs Transitional fossils Taxa named by Alfred Romer Fossil taxa described in 1970