Mylodontoidea

Casali, Daniel M, Boscaini, Alberto, Gaudin, Timothy J & Perini, Fernando A, 2022, Reassessing the phylogeny and divergence times of sloths (Mammalia: Pilosa: Folivora), exploring alternative morphological partitioning and dating models, Zoological Journal of the Linnean Society 196 (4), pp. 1505-1551 : 1522

Mylodontoidea

PP = 100, age = 29.46 Mya (26.67–32.60).

The clade is composed of Scelidotheriidae, Mylodontidae and three stem mylodontoid genera, Octomylodon , Octodontotherium and Paroctodontotherium , with this pattern being consistently recovered in all analyses performed in this study. Those three genera are recovered as successive sister groups to ( Scelidotheriidae , Mylodontidae ) in analyses with all H, UN_p and some A models. On the other hand, Octodontotherium and Paroctodontotherium are sister taxa and more closely related to ( Scelidotheriidae , Mylodontidae ) in MP analyses, and in some A models. In other analyses, using UN_e and other A models, the three genera were recovered as a clade and sister to Mylodontidae or to Mylodontinae , depending on the analysis.

Mylodontoidea was supported by eight synapomorphies (four for both methods and four exclusively for BI): absence of a mediolateral bulge in horizontal ramus of mandible, at toothrow (BI); absence of a medial ridge running along anterior edge of coronoid process; short and deep angular process (BI); condyles at or just above level of toothrow; mandibular symphysis longer than molariform toothrow (BI); snout elevated anteriorly; absence of prominent lateral walls in lacrimal foramen; and dorsal edge of entotympanic with a strong concave curvature in lateral view, with dorsal projection at anterior end (BI).