Aspidosaurus

Aspidosaurus is an extinct genus of dissorophoid temnospondyl within the family Dissorophidae.

Aspidosaurus Temporal range: Late Carboniferous - Early Permian
Aspidosaurus Skull
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Order:	†Temnospondyli
Family:	†Dissorophidae
Genus:	†Aspidosaurus Broili, 1904
Species
†A. chiton Broili, 1904 (type) †A. apicalis †A. crucifer †A. glascocki †A. binasser Berman and Lucas, 2003
Synonyms
Alegeinosaurus Case, 1911

Description

Like other dissorophids, Aspidosaurus species had a single row of plates formed by expansions of the neural spines.[1]

Taxonomy

In 1911, Paul Miller discovered the remains of various dissorophid bones in New Mexico that were attributed to a new species, Aspidosaurus novomexicanus. The skull closely resembled that of a specimen of Cacops aspidephorus found in Texas 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 vertebrae.[1] A. novomexicanus was later attributed to the genus Broiliellus. 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 and is referred to as the "Rio Arriba taxon" because of its uncertain phylogenetic placement.[2]

The genus Alegeinosaurus Case, 1911 was synonymized with Aspidosaurus by Gee (2018) based on a redescription of the holotype.[3]

Phylogeny

Below is a cladogram 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:[2]

[2]

Dissorophoidea

Micromelerpetontidae   Micromelerpeton       Amphibamidae   Platyrhinops     Doleserpeton     Olsoniformes Trematopidae   Ecolsonia     Fedexia       Tambachia     Anconastes       Phonerpeton     Acheloma         Dissorophidae   Platyhystrix     Aspidosaurus       Conjunctio   Dissorophinae   Dissorophus     Broiliellus texensis     Broiliellus brevis     Broiliellus olsoni     Cacopinae   Brevidorsum       Admiral taxon     Rio Arriba taxon       Cacops morrisi     Cacops aspidephorus       Kamacops     Zygosaurus

References

1. A Description of Aspidosaurus novomexicanus Williston Permo-Carboniferous Vertebrates from New Mexico, p7-11. Retrieved 2011-09-11.
2. Schoch, R. R. (2012). "Character distribution and phylogeny of the dissorophid temnospondyls". Fossil Record. 15 (2): 121–137. doi:10.1002/mmng.201200010.
3. Bryan M. Gee (2018). "Reappraisal of the early Permian dissorophid Alegeinosaurus from Texas, USA". PalZ. in press. doi:10.1007/s12542-018-0421-9.