''Cromptodon'' is an extinct
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
cynodont
The cynodonts () (clade Cynodontia) are a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 mya), and extensively diversified after the Permian–Triassic extinction event. Cynodonts had a wide variety ...
s from the
Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
of Cerro Bayo de Portrerillos,
Cerro de las Cabras Formation,
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
,
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
. It is known only from PVL 3858, a mandible.
Description
The skull has been estimated to have a length of .
The morphology and distribution of the cups on the postcanines is considered to be very similar to ''
Thrinaxodon liorhinus
''Thrinaxodon'' is an extinct genus of cynodonts, most commonly regarded by its species ''T. liorhinus'' which lived in what are now South Africa and Antarctica during the Early Triassic. ''Thrinaxodon'' lived just after the Permian–Triassic m ...
'' differing in the fact that the
cingulum is lingually wider. The coronoid, prearticular and angular processes, Bonaparte considered, were more developed than those in ''Thrinaxodon'', being more similar to ''Tribolodon'' (now ''
Bolotridon
''Bolotridon'' is an extinct genus of epicynodontian cynodont. It was renamed from its original genus designation of ''Tribolodon'' (Harry Govier Seeley, 1895), which was already occupied by a genus of cyprinid fish named in 1883 by Sauvage. The ...
''). The lower postcanines are buccolingually expanded.
Classification
Bonaparte originally classified ''Cromptodon'' as a
galesaurid
Galesauridae is an extinct family of cynodonts. Along with the family Thrinaxodontidae and the extensive clade Eucynodontia (which includes mammals), it makes up the unranked taxon called Epicynodontia. Galesaurids first appeared in the very lat ...
. In 1991, J. A. Hopson, pointed out a resemblance between the teeth of ''Cromptodon'' and juvenile ''
Aleodon
''Aleodon'' is an extinct genus of cynodonts that lived from the Middle to the Late Triassic. Relatively few analyses have been conducted to identify the phylogenetic placement of ''Aleodon'', however those that have place ''Aleodon'' as a siste ...
'' and reclassified ''Cromptodon'' as a
chiniquodontid
Chiniquodontidae is an extinct family of basal probainognathian cynodonts that lived in what is now Africa and South America during the Middle and Late Triassic. It is currently thought to include two valid genera: ''Aleodon'' and ''Chiniquodo ...
. In 2003, Fernando Abdala and Norberto P. Giannini systematically described Chiniquodontidae and found both ''Cromptodon'' and ''Aleodon'' to fall outside of Chiniquodontidae as both lacked features their study found to be diagnostic of the family, although additional material was required to provide a definite taxonomic placement.
See also
*
List of therapsids
References
Prehistoric cynodont genera
Anisian life
Middle Triassic synapsids of South America
Triassic Argentina
Fossils of Argentina
Fossil taxa described in 1972
Taxa named by José Bonaparte
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