A particular specimen of Panochthus Burmeister (Xenarthra,Glyptodontidae) from the late pleistocene of the Tarija valley, Bolivia

CUADRELLI F.; ROIG M; ZAMORANO M.; ZURITA A. E.

Jornada; Reunión Anual de Comunicaciones de la Asociación Paleontológica Argentina; 2022

The Late Eocene-Late Pleistocene Cingulata Glyptodontidae (Xenarthra, Mammalia) are distributedin two radiations, one northern and one southern. Within the latter, Panochthus Burmeister, 1866(Late Pliocene-Late Pleistocene) stands out for its great diversity, its wide distribution (from 47° 01'S 67° 14' W, to 05° 11' S 39° 17' W) and for having records at more than 4,000 m.a.s.l., however,knowledge about taxa from northeastern Brazil (i.e., P. greslebini and P. jaguaribensis) and subAndean areas in Bolivia (i.e. P. hipsilis, P. intermedius and Panochthus sp.) is limited.In thisscenario, we present a new specimen from the Late Pleistocene of Tarija (Bolivia), MNPAV/006920, which includes a complete skull, cephalic shield and dorsal armor. At the cranial level,MNPA-V/006920 differs from the Late Pleistocene species from the Pampean region (P.tuberculatus MHGN-633/02 and P. frenzelianus AMNH-11243) and from highland areas (P.hipsilis MURB-1906A and P. intermedius MHNC-13491) by presenting simple Mf1 (as in P. cf. P.subintermedius MLP-84-IX-2-11, late early Pleistocene of the Pampean region); orbit of largerrelative diameter (although similar to P. intermedius MHNC-13491); absence of post-orbital bar(characteristic of P. tuberculatus), scarcepneumatization in the nasal region and concave frontonasal profile, these last two characteristics being the most conspicuous. On the other hand, thefronto-nasal area of P. cf. P. subintermedius has not been preserved; preventing its comparison withMNPA-V/006920.The cephalic shield can be divided into a peripheral and a medial region. Thelatter has three rows of osteoderms (5-3-2 in number) with broad central figures, convex surface andconcentric foramina (2-4-3 in number in P. tuberculatus and 1-3-2 in P. intermedius MHNC-13491and in both cases these figures are flat and striated). Unlike other panochtines, these three rows areseparated from each other by osteoderms of smaller diameter and with an evident central figure. Themaximum height of the dorsal armor is at the level of the middle region (similar but less convexthan in P. intermedius and P. frenzelianus, and different from P. tuberculatus, P. hypsilis and P.subintermedius). With the exception of the mid-dorsal region, it is possible to observe centralfigures, although in smaller number and relative diameter than in above mentioned species of thegenus. This combination of characters suggests that MNPA-V/006920 may represent a new speciesof Panochthus. However, the dorsal armor of P. jaguaribensis and P. floresiensis is still unknown,which prevents a rigorous comparison between these taxa and MNPA-V/006920.