The earliest mustelid in North America

Abstract

Until now, the pre-Miocene fossil record of mustelids in North America has been restricted to specimens attributable to oligobunine taxa and isolated remains tentatively allocated to the genus Plesictis. In the present study, we report on a nearly complete cranium and a referred dentary of a new genus and species of mustelid. The specimens were recovered from the Turtle Cove and Kimberly Members of the John Day Formation, Oregon, USA. These excellently preserved specimens more confidently confirm the presence of mustelids in the Early and Late Oligocene (Early and Late Arikareean) of North America. Like the holotype specimen of ‘Plesictis’ julieni, the new species lacks an alisphenoid canal and a postprotocrista on the M1 (synapomorphies of Mustelidae), but retains a dorsally deep suprameatal fossa (a feature occasionally suggested to be unique to Procyonidae). Phylogenetic analyses, applying parsimony and Bayesian inference to combined molecular (five genes totalling 5490 bp) and morphological data, recover this new species of mustelid as sister-species to ‘Plesictis’ julieni. The results of these analyses reveal that the new genus is a close relative of other species of Plesictis and several taxa traditionally allied with Oligobuninae, thereby rendering Oligobuninae paraphyletic. We further discuss the significance of the relatively small size of this new mustelid as it relates to predictions based on increased aridification of the palaeoclimate and the expansion of open habitats in the Oligocene.

?Amphictis(Carnivora, Ailuridae) from the Belgrade Formation of North Carolina, USA

“…Among the musteloids, Mustelictis from the early Oligocene (MP 22, 32 Ma) of Quercy, France ( De Bonis, 1997 ) is one of the earliest stem mustelids ( Wang, McKenna & Dashzeveg, 2005 ). Corumictis wolsani , from the early Arikareean (Ar1, MP 24 equivalent, 30–28 Ma and Ar2) of Oregon, is the earliest stem mustelid in North America and is an immigrant taxon ( Paterson et al, 2020 ). Promartes is the only oligobunine mustelid known from the Arikareean.…”

Peer Review #2 of "?Amphictis (Carnivora, Ailuridae) from the Belgrade Formation of North Carolina, USA (v0.1)"

“…Among the musteloids, Mustelictis from the early Oligocene (MP 22, 32 Ma) of Quercy, France (Bonis, 1997) is one of the earliest stem mustelids (Wang, McKenna & Dashzeveg, 2005). Corumictis wolsani, from the early Arikareean (Ar1, MP 24 equivalent, 30-28 Ma and Ar2) of Oregon, is the earliest stem mustelid in North America and is an immigrant taxon (Paterson et al, 2020). Promartes is the only oligobunine mustelid known from the Arikareean.…”

An exquisitely preserved skeleton of Eoarctos vorax (nov. gen. et sp.) from Fitterer Ranch, North Dakota (early Oligocene) and systematics and phylogeny of North American early arctoids (Carnivora, Caniformia)

“…However, in recent years, new data from early musteloids are entering into the discussion from the North American record. These new records, such as Corumictis wolsani Paterson et al (2020b) and Oaxacagale ruizi Ferrusiquía-Vallafranca and Wang (2021), show that North America is perhaps equally important in our understanding of early arctoid divergence.…”

“…Baskin and Tedford (1996) and Baskin (1998) reverted the genus back to a stem musteloid position, a conclusion also shared by Wang et al (2005a). Paterson et al (2020b), however, presented a phylogenetic analysis of early musteloids and arrived at very different positions for Mustelavus in two different trees (see Phylogeny below).…”

“…The North American records have finally begun to catch up. In fact, North America appears to have played an important role in the early diversification of Caniformia, with stem taxa for Amphicyonidae, Canidae, Ursidae, and Musteloidea (Wang and Tedford, 1994; Tomiya and Tseng, 2016; Paterson et al, 2020b). The age relationships of these stem taxa are also generally earlier than their European counterparts.…”