New material of Incadelphys antiquus (Pucadelphyda, Metatheria, Mammalia) from the early Palaeocene of Bolivia reveals phylogenetic affinities with enigmatic North and South American metatherians

The present paper describes a partial skull referred to Incadelphys antiquus, from the early Palaeocene of Tiupampa (Bolivia). specimen includes anterior part with maxillae, premaxillae, nasals, lacrimals, frontals and jugal, both dentaries. Most teeth are preserved except some incisors. Some major characteristics elongation slenderness rostrum as compared other taxa narrowness blade-like morphology premolars. new is Tiupampan pucadelphydans, especially, pucadelphyids, but also sparassodonts. Comparisons Marmosopsis juradoi, Eocene Itaboraí Aenigmadelphys archeri latest Campanian North America meaningful. Among others, three genera share strong distolabial extension their metastylar area M1, which has not been observed, such extant, in American metatherians. A phylogenetic parsimony analysis performed exclusion poorly known taxa, Jaskhadelphys minutus (two upper molars only), or Kiruwamaq chisu (one M?3 only) late Peru. included our at least all lower molars. result unweighted characters retrieved inclusion Incadelphys, Marmosopsis, Szalinia clade Pucadelphyda, Pucadelphyidae Sparassodonta. An downweighted homoplastic (with Goloboff K=3) resulted monophyletic grouping Szalinia, Aenigmadelphys, an unnamed designated working term SAMI (after initial these four genera). This result, we favor, first hypothesis suggests close relationship between - Eocene, -Itaboraí pucadelphydans Late Cretaceous taxon, within Pucadelphyda.