Luangwa sudamericana (Triassic cynodont, Brazil) postcranial skeleton

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

A new paper:

Nicole L. Souza, Fernando Abdala, Francesco Battista & Ana M. Ribeiro (2025)
The postcranial skeleton of Luangwa sudamericana (Traversodontidae: Cynodontia) from the Middle-Late Triassic of southern Brazil
Journal of South American Earth Sciences 105546
doi: https://doi.org/10.1016/j.jsames.2025.105546
https://www.sciencedirect.com/science/article/abs/pii/S0895981125002081


Highlights

First detailed description of Luangwa sudamericana skeleton;
First description of the clavicle, ulna and radius attributed to Luangwa;
Traversodontidae occured Anisian–Norian;
Few traversodontid species have described postcranium;
The material studied is most similar to L. drysdalli.

Abstract

Traversodontidae represent a highly successful lineage of Triassic Cynodontia, renowned for their taxonomic diversity and abundance. Characterized by their labiolingually expanded gomphodont postcanines, traversodontids also display a wide range of body sizes. Despite their evolutionary, paleobiological and biostratigraphy significance, studies on their postcranial anatomy remain limited. Here, we provide the first description of the postcranium of Luangwa sudamericana, based on the specimen MCN-PV 10500, recovered from the Middle-Late Triassic, Bortolin site, Santa Maria Supersequence. The specimen includes partially disarticulated vertebrae, ribs, and elements of shoulder and pelvic girdles, as well as hindlimb and forelimb bones. Specialized rib morphologies closely resembling the different stages of the ribs of the African species L. drysdalli are present. The humerus also shares comparable proportions and anatomical features with L. drysdalli, supported by regression analyses. Characteristics as prominent lesser tuberosity, robust entepicondyle and supracondylar crest were observed in the humerus of MCN-PV 10500, L. drysdalli and L. sudamericana (MCN-PV 10314). Similar morphology of anterior and posterior process of the ilium, distinctive femoral greater trochanter, and anterodorsally deflected femoral head are additional similarities that support a close relationship between MCN-PV 10500 and L. drysdalli. Taphonomic and sedimentological evidence, as well as the preservation mode, suggest that the specimen was preserved in fluvial floodplain deposits, with variable bone surface preservation reflecting distinct depositional and diagenetic conditions. Although studies about the postcranial anatomy of cynodonts are quite limited the shared features of MCN-PV 10500 and L. drysdalli supports the assignment to L. sudamericana.