Scelidotheriinae Ameghino, 1904

Verger, Kévin Le, 2023, Xenarthrans of the collection of Santiago Roth from the Pampean Region of Argentina (Pleistocene), in Zurich, Switzerland, Swiss Journal of Palaeontology (3) 142 (1), pp. 1-39 : 25

Scelidotheriinae Ameghino, 1904

Indet.

Referred material: Right jugular and dorsal vertebra: PIMUZ A/ V 514; mandible fragment bearing four broken teeth: PIMUZ A/ V 518; incomplete cranium and one astragalus: PIMUZ A/ V 526; altered anterior part of the cranium: PIMUZ A/ V 527; six caudal vertebrae: PIMUZ A/ V 529; one radius: PIMUZ A/ V 530; one foot bone: PIMUZ A/ V 4104; one ulna: PIMUZ A/ V 4134; rostrum bearing teeth and a part of the mandible: PIMUZ A/ V 5699.

Comment: Te Scelidotheriinae are by far the most abundant group in the Roth collection at PIMUZ. Following multiple revisions on the diversity of the ‘subfamily’, only three genera are recognized in the Pleistocene: Scelidotherium Owen, 1839a , Catonyx Ameghino, 1891 , and Valgipes Gervais, 1873 (e.g., Miño-Boilini & Carlini, 2009; Miño-Boilini & Quiñones, 2020). Among them, four species are known to occur in the Pampean Region: Scelidotherium leptocephalum Owen, 1839a , Scelidotherium bravardi Lydekker, 1886 , Catonyx cuvieri Lund, 1839 , and Catonyx tarijensis Gervais & Ameghino, 1880 ( Miño-Boilini & Quiñones, 2020). Te Scelidotheriinae group now has extensive diagnoses including cranial, dental, and postcranial diagnostic features (e.g., Miño-Boilini et al., 2014), which helps to avoid confusion with other mylodontines. Specific identification, however, focuses primarily on variations in dentition and autopod traits (e.g., Corona et al., 2013; Nieto et al., 2021). Identification of PIMUZ A/V 5699 is only possible at ‘subfamilial’ rank due to the early ontogenetic stage of the specimen. Because of the presence of laterally compressed molariforms and a relatively elongated cranium, an attribution to the Scelidotheriinae is the most likely ( Miño-Boilini et al., 2019). PIMUZ A/V 514, a young specimen, and PIMUZ A/V 529 are present only through the preservation of caudal vertebrae and a jugal (PIMUZ A/V 514), parts of the skeleton that do not provide particularly diagnostic features. PIMUZ A/V 526, PIMUZ A/V 530, PIMUZ A/V 4104, and PIMUZ A/V 4134 correspond to an altered cranium, long bones, and foot bones for which the only potential diagnostic information corresponds to the relatively large size of these specimens, a fragile argument for this clade. Finally, PIMUZ A/V 518 and PIMUZ 527 are far too altered to distinguish diagnostic traits. Because of the alteration of these specimens, their relatively young age or the absence of diagnostic elements, I favor an attribution to the ‘subfamily’ level.