''Aspidosaurus'' 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 ...

dissorophoid Dissorophoideans are a clade of medium-sized, temnospondyl amphibians that appeared during the Moscovian in Euramerica, and continued through to the Late Permian and the Early Triassic of Gondwana. They are distinguished by various details of the ...

temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order (biology), order of small to giant tetrapods—often considered Labyrinthodontia, primitive amphi ...

within the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Dissorophidae Dissorophidae is an extinct family of medium-sized, temnospondyl amphibians that flourished during the late Carboniferous and early Permian periods. The clade is known almost exclusively from North America. History of study Dissorophidae is a ...

Description

Like other dissorophids, ''Aspidosaurus'' species had a single row of plates formed by expansions of the neural spines.A Description of ''Aspidosaurus novomexicanus'' Williston
Permo-Carboniferous Vertebrates from New Mexico, p7-11. Retrieved 2011-09-11.

Taxonomy

In 1911, Paul Miller discovered the remains of various dissorophid bones in

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

that were attributed to a new species, ''Aspidosaurus novomexicanus''. The skull closely resembled that of a specimen of ''

Cacops aspidephorus ''Cacops'' ("ugly look" for its strange appearance), is a genus of dissorophid temnospondyls from the Kungurian stage of the early Permian of the United States. ''Cacops'' is one of the few olsoniforms (dissorophids and the larger trematopids) w ...

'' found in

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

but the arrangement of ridges in the otic region was different. The teeth found were slender and conical and all of an approximately equal size. The vertebral column, pelvis and limb bones were also similar but the new specimen was distinguished from ''Cacops'' by the armour, the single row of vertical plates that were originally attached to the neural spines of the

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

e. ''A. novomexicanus'' was later attributed to the genus ''

Broiliellus ''Broiliellus'' is an extinct genus of dissorophoid temnospondyl within the family Dissorophidae. ''Broiliellus'' is most closely related to the genus ''Dissorophus'', and both have been placed in the subfamily Dissorophinae. ''Broiliellus'' is k ...

''. More recently, ''"A." novomexicanus'' has been removed from ''Broiliellus'' and classified as a closer relative of ''Cacops''. The original specimen is now housed in the

University of California Museum of Paleontology The University of California Museum of Paleontology (UCMP) is a paleontology museum located on the campus of the University of California, Berkeley. The museum is within the Valley Life Sciences Building (VLSB), designed by George W. Kelham and ...

and is referred to as the "Rio Arriba taxon" because of its uncertain

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

placement. The genus ''Alegeinosaurus'' Case, 1911 was synonymized with ''Aspidosaurus'' by Gee (2018) based on a redescription of the holotype.

Phylogeny

Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...

from Schoch (2012) in which valid ''Aspidosaurus'' species are found to be basal dissorophids and ''"Aspidosaurus" novomexicanus'' -the Rio Arriba taxon- nests within the subfamily Cacopinae:

References

Dissorophids Carboniferous amphibians of North America Cisuralian amphibians of North America Pennsylvanian first appearances Cisuralian genus extinctions Prehistoric amphibian genera {{temnospondyli-stub