A new derorhynchid (Mammalia, Metatheria) from the early Eocene Itaboraí fauna of Brazil with comments on its affinities

Abstract

A new early Eocene, small-sized metatherian from the Itaboraí fauna is described. The new taxon is recognized on the basis of an incomplete dentary recovered from fi ssure fi llings in the travertine limestones from the Itaboraí Basin, State of Rio de Janeiro, Brazil. The phylogenetic analysis placed the new genus and species as the sister taxon of Derorhynchus, undescribed Derorhynchidae, and Coona plus Pauladelphys.When compared to Derorhynchus, the new taxon exhibits a shorter dentary, in which the fi rst lower premolar is not separated from the second by a diastema, and shows second and third lower molars with subequal trigonid and talonid width (in Derorhynchus the talonids are wider than the trigonids). This new taxon shows some plesiomorphic traits when compared with the remaining derorhynchids, such as the shallower dentary (less than 1.5 mm), and conical entoconids rather than fl attened in shape. The combination of very small size (~13-20g), sharp crests, tall and slender cuspids, broad talonid basins, as well as trigonid taller than the talonid is suggestive of an insectivorous diet for the new taxon.

A sabre-tooth predator from the Neotropics: Cranial morphology of Anachlysictis gracilis Goin, 1997 (Metatheria, Thylacosmilidae), based on new specimens from La Venta (Middle Miocene, Colombia)

“…14). A position of the Tiupampan taxa (or at least of Mayulestes , which has been included in high levels phylogenetic analyses since the nineties) stem to the monophyletic group that includes sparassodonts (as defined above) agrees with the topologies obtained by Rougier et al (1998), Babot (2005), Forasiepi (2009), Engelman & Croft (2014), Forasiepi et al (2015), Suarez et al (2016), Wilson et al (2016), Carneiro (2018), Rangel et al (2019), Engelman et al (2020), Oliveira et al (2021), among others.…”

Papers in Paleontology - Festschrift in honor of Diogenes de Almeida Campos

“…Among his latest papers, he published with a young paleontologist a description of new crocodylomorphs from his home state of Bahia (Souza & Campos 2019). He has been honored several times with genera and species dedicated to him (e.g., Leonardi 1979, Kellner 1987, including in the present volume (Oliveira et al 2021).…”