A reassessment of Nemolestes (Mammalia, Metatheria): Systematics and evolutionary implications for Sparassodonta

Off the script and crypt: the systematic affinities and evolutionary significance of an unexpected Sparassodonta (Mammalia, Metatheria) from Itaborai Basin (early Eocene)

“…Rangel et al (2019) identi ed the m1 of Patene simpsoni as the most generalized of its lower molars, with less evident dental features indicative of carnivory (see also Rangel et al 2023a, b). On the contrary, the m2, and specially m3, of this species show proportionally smaller talonids in comparison with trigonids, which supports less developed protocones on antagonistic upper molars (M2-3) (see Rangel et al 2019Rangel et al , 2023a). An oppose condition is observed for the m1 of this species and the lower molars of Xenocynus crypticus, which show a talonid subequal to wider than the trigonid.…”

“…2a), it is deductible that the protoconid of m4 e clearly more developed than the one of m3, and this one from the one of m2. This pattern is observable in most sparassodonts due to the increase in the size of the lower molars from m1 to m4 (see e.g., Rangel et al 2019Rangel et al , 2023aRangel et al , 2023bSuarez et al 2023). This morphology and the presence of short (= mesio-distally compressed) lingual alveolus of upper molars support the identi cation of these maxillae to a Sparassodonta.…”

“…All the Brazilian specimens are from the Itaboraí Basin, São José de Itaboraí, Rio de Janeiro State (Rangel et al 2019(Rangel et al , 2023a(Rangel et al , 2023b) (Fig. 1).…”

“…These taxa display at labial borders of paracone and metacone, spaced paracone and metacone, talonid wider than the trigonid and a labial contact of the cristid obliqua with the distal border of the trigonid on m1-3. This combination of features is suggestive of a generalized diet (mesocarnivory or omnivory) for them (see e.g., Zimicz 2012; Rangel et al 2019Rangel et al , 2023aRangel et al , 2023b. In line with this conclusion, Hondadelphys eldsi has been recently considered as a generalized sparassodont (see Rangel et al 2023b).…”

“…Sedor et al 2017), Nemolestes and Chlorocyon, as the sister taxa of Borhyaenoidea and the unnamed clade A (Dukecynus + Pseudolycopsis, Lycopsis, [Procladosictis, Hondadelphys + Stylocynus] + Hathliacynidae; sensuRangel et al 2023a). This result is based on the following shared characters: vestigial to absent StD (character 20, state 0), StE absent (ch.…”