New anatomical and phylogenetic data on the Late Neogene armadillo Macrochorobates scalabrinii (Chlamyphorindae, Euphractinae)

BARASOAIN DANIEL ; BONINI RICARDO; ZURITA, ALFREDO; TOMASSINI, RODRIGO L.

virtual

Jornada; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2020

Macrochorobates is a genus of big sized Euphractinae armadillos restricted to the late neogene of Argentina. it includes thespecies M. scalabrinii and M. chapalmalensis. Particularly, M. scalabrinii is recorded in the late Miocene (Chasicoan?Huayquerian)of Buenos Aires, La Pampa, and San Juan provinces, and the late Miocene?early Pliocene (Messinian?zanclean) of Tucumán,La Rioja, Catamarca, and Jujuy provinces. Most specimens are represented by isolated osteoderms, while more completespecimens are quite rare. We analyze here the most complete dorsal carapace (FMnH-P14510) and skull (FMnH-P14360)known for the genus, coming from late Miocene?early Pliocene levels of Andalhuala Formation outcropping at Puerta deCorral Quemado and Santa María Valley localities respectively, in Catamarca Province. This study provides the first detailedanatomical description of the skull and increases the knowledge of the dorsal carapace morphology. These aspects allowedto include this taxon for the first time into a morphological phylogenetic analysis. obtained results support its inclusionwithin Euphractinae, revealing a close affinity with other late neogene genera, and a sister group relationship with thegenus Macroeuphractus, based on: a) anterior teeth oriented obliquely to the long axis of toothrow; b) very flattenedbraincase with parietals dorso-ventrally compressed; c) well developed sagittal crest; d) large and wide orbits; e)underdeveloped scapular shield of the dorsal carapace; and f) mobile osteoderms with very deviated central figures andundivided peripheral figures. Geographic distribution seem to vary with its biochron, as older records come from PampeanRegion while most modern ones come from Cuyo and noA regions.