Notochampsa

*Notochampsa* is an extinct genus of notochampsid crocodilian that lived in Lesotho during the Early Jurassic.

## History

*N. istedana* was briefly named by Broom (1904), and was quickly joined by *N. longipes*. Both were poorly defined, as they had poor descriptions and many aspects contradicted, in part due to poor preservation. It was then considered an early-branching "protosuchian". Since then, *Notochampsa* was then disregarded, labelled as a nomen dubium. Haughton (1924) finds the genus as valid, but the species to not be congeneric since *N. longipes* has "truer" crocodilian traits and *N. istedana* has features not congruent with "crocodilian" traits. Thus, *N. longipes* was reassigned to *Erythrochampsa*, hypothesizing *N. istedana* was closely related to *Pedeticosaurus*, and both as notochampsids. Since, many confusing taxonomic statements have been stated. *Notochampsa* has also historically been assigned to Aetosauridae and Erpetosuchidae. However, Dollman et al. (2021) recover *Notochampsa* as monotypic, containing only *N. istedana*, and to be valid. They also provide a better description in attempt to clear the taxonomic history of this taxon.

## Description

SAM-PK-4013 is the holotype, including a skull, a fragmentary back leg, a somewhat complete forelimb, most of the shoulder girdle, back osteoderms, a 20x2 (36 in total) row of back osteoderms, 8 partial ribs and a disarticulate skull. It is in a very fine-grained, pale olive sandstone block. This block preserves the individual from the top side and the underside. CT scanning reveals more elements may be enclosed within the matrix. It bears a lack of biscuspid dentition, an elongate posterolateral squamosal extension from the posterolateral corner, a frontal with an anterior that separates a posterior process from the nasals, broadly-expanded anterior and posterior intercostal ridges of the dorsal ribs, an extremely anteroposteriorly-extensive symphasis that goes posteriorly between the 6th and 7th alveolus and tapers anteriorly in the medial, a ventral surface of the coracoid that has an elongate posterior process, large, paired, labiolingually-compressed entary caniniforms in alveoli 3 and 4, labiolingually-compressed post-caniniform denatry teeth and at least 4 maxillary teeth; these all distinguish Notochampsa as a genus from other notochampsids.

## Classification

Along with *Notochampsa* being resurrected as a valid taxon by Dollman et al. (2021), they also brought Notochampsoidea and Notochampsidae to classify *Notochampsa*. Notochampsidae is defined to include *Notochampsa*, *Orthosuchus*, their concestor and all of their descendants. Notochampsoidea is defined as including *Notochampsa*, *Protosuchus*, their concestor and all of their descendants, being the first "true" and earliest crocodilians. Unweighted and unconstrained parsimony analysis was done to find *Notochampsa* as a sister taxon to *Orthosuchus*. The revelation that Notochamspoidea are a group of basal-diverging "true" crocodilians indicates that early crocodilians were much more diverse than initially thought. Notochampsidae is found as the sister to Protosuchidae in Notochampsoidea, which is found to be monophyletic. They find:

## Paleoecology

Dollman et al. (2021) visited the original site to find extensive biostratigraphic data, finding *Notochampsa* is from the Pliensbachian-aged Clarens Formation. Historically, it was deemed unknown where *Notochampsa* was originally collected. This period in time is notoriously barren in the vertebrate fossil record. *Notochampsa* lived in a dry, desert environment. Desert crocodilians are rare to find, so *Notochampsa* is hypothesized to have had strange adaptations toward this. The holotype was recovered at Funnystone farm near Rhodes, Eastern Cape Province, South Africa. It was discovered by a Mr. Art Isted and later named by Dr. Robert Bloom. This farm is located within the *Massospondylus* Assemblage Zone of the Clarens Formation. Based on the original discoverer's grandson, Mr. Bob Viedge, a small outcrop consists of fingrained, pale, olive sandstone, much like the one the holotype is encased in. The homestead bears a small outcrop exposed immediately. This area is ~65 meters above the Elliot/Clarens Formation contact point. *Tritylodontoides*, *Pachygenelus*, *Diarthrognathus*, *Massospondylus*, *Ngwevu* and *Lycorhinus* are some taxa described from the Clarens Formation.

## References

* https://en.wikipedia.org/wiki/Notochampsa
* https://www.tandfonline.com/doi/abs/10.1080/14772019.2021.1948926?scroll=top&needAccess=true&journalCode=tjsp20
* https://twitter.com/katpalaeo/status/1442763478889009155
* https://en.wikipedia.org/wiki/Clarens\_Formation