Megatheriinae, Gill, 1872

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 : 1529

Megatheriinae

PP = 100, age = 15.28 Mya (13.30–17.45).

The clade, which was recovered in all of our analyses, is composed of the stem genera Diabolotherium and Megathericulus and the clades Thalassocnini and Megatheriini. The arrangement ( Diabolotherium , ( Megathericulus , (Thalassocnini, Megatheriini))) was recovered in all BI analyses and in par_IW10. In par_EW and par_IW100, the order of divergence between Diabolotherium and Megathericulus is reversed, whereas in par_IW5, Aymaratherium and Thalassocnus are successively sister taxa to Megatheriini, not forming a clade.

Megatheriinae was supported by 16 synapomorphies (11 for both methods and five exclusively for BI): Cf1 and cf1 dorsoventrally aligned with molariforms; absence of a well-developed diastema between Cf1/cf1 and molariforms; Cf1 within size range of molariforms; cf1 within size range of molariforms; molariform morphology of Cf1/cf1; trapezoidal Cf1 cross-section; trapezoidal cf1 cross-section; absence of a mandibular fossa posterior to cf1; nuchal crest continuous with dorsal edge of zygomatic process of squamosal (BI); anteroventrally inclined zygomatic process of squamosal; postorbital process roughly at the level of maxillary foramen (BI); distinct neck present at the base of occipital condyles (BI); carotid foramen partially covered ventrally by entotympanic and ectotympanic, in ventral view; glenoid fossa well separated from porus acusticus (BI); absence of entepicondylar foramen of humerus; and medial (trochlear) portion of trochlear notch extends proximal to lateral (capitular) portion (BI).