Mylodontidae

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 : 1523

Mylodontidae

PP = 100, age = 19.84 Mya (16.56–22.90).

This taxon, composed of the clades Urumacotheriinae and Mylodontinae , was recovered in all analyses performed in this study, except the analysis using the UN_e model, in which Urumacotheriinae was recovered as sister to a clade composed of stem mylodontoids and Mylodontinae .

Mylodontidae was supported by 29 synapomorphies (13 for both methods and 16 exclusively for BI): Cf1 larger than the largest molariform (BI); anteroposteriorly ovate Mf2 and Mf3 cross-section (BI); anteroposteriorly ovate mf2 cross-section (BI); elongate and irregularly lobate mf3 cross-section (BI); presence of a corkscrew-like rotation in the plane of articulation of mandibular condyle; presence of buccinator fossa of maxilla; frontal and parietal flattened anteroposteriorly and mediolaterally; frontal sinus extends into nasal and parietal bones (BI); ectotympanic oriented anteromedially; absence of styliform process of ectotympanic; mastoid broadly exposed laterally (BI); stylomastoid canal ventrolaterally directed (BI); absence of entepicondylar notch (BI); lateral and medial epicondyles equally expanded in anterior view; olecranon quadrate in lateral view, with anterior and posterior margins parallel or diverging proximally; oval shape of radial head, in proximal view (BI); straight posterior border of radius, in lateral view; roughly straight radial diaphysis (BI); quadrangular laterodistal corner of scaphoid, in dorsal view; intermediate tibial length, more than two times the width, but less than three times; lateral facet of anterior border of tibial proximal epiphysis located posterior to medial facet (BI); two deep grooves for tendons of m. flexor hallucis longus, m. flexor digitorum longus and m. tibialis caudalis; fibular facet of astragalus restricted to anterior surface (BI); discoid process of astragalus flat or roughly so, in lateral view; proximodistal length of the astragalus greater than or equal to anteroposterior length (BI); calcaneus tuberous and expanded, with distal apex rounded (BI); confluence between sustentacular facet and cuboid surface of calcaneus (BI); presence of an oblique crest on plantar side of calcaneus (BI); and broadly contiguous facets for cuboid and metatarsal III, in metatarsal IV.