A new species ofGulofrom the Early Pliocene Gray Fossil Site (Eastern United States); rethinking the evolution of wolverines

Abstract

The wolverine (Gulo gulo) is the largest living terrestrial member of the Mustelidae; a versatile predator formerly distributed throughout boreal regions of North America and Eurasia. Though commonly recovered from Pleistocene sites across their range, pre-Pleistocene records of the genus are exceedingly rare. Here, we describe a new species of Gulo from the Gray Fossil Site in Tennessee. Based on biostratigraphy, a revised estimate of the age of the Gray Fossil Site is Early Pliocene, near the Hemphillian—Blancan transition, between 4.9 and 4.5 Ma. This represents the earliest known occurrence of a wolverine, more than one million years earlier than any other record. The new species of wolverine described here shares similarities with previously described species of Gulo, and with early fishers (Pekania). As the earliest records of both Gulo and Pekania are known from North America, this suggests the genus may have evolved in North America and dispersed to Eurasia later in the Pliocene. Both fauna and flora at the Gray Fossil Site are characteristic of warm/humid climates, which suggests wolverines may have become ‘cold-adapted’ relatively recently. Finally, detailed comparison indicates Plesiogulo, which has often been suggested to be ancestral to Gulo, is not likely closely related to gulonines, and instead may represent convergence on a similar niche.

Peer Review #1 of "First occurrence of the enigmatic peccaries Mylohyus elmorei and Prosthennops serus from the Appalachians: latest Hemphillian to Early Blancan of Gray Fossil Site, Tennessee (v0.1)"

“…Manuscript to be reviewed Recent assessment of the mammalian fauna suggests an age of 4.9 to 4.5 Ma for the GFS (Samuels, Bredehoeft & Wallace, 2018). This suggestion brings the maximum age of the GFS to be in line with that of the Palmetto Fauna of Florida, which is interpreted to be 5.0-4.5 Ma (Tedford et al, 2004;Webb et al, 2008).…”

First occurrence of the enigmatic peccariesMylohyus elmoreiandProsthennops serusfrom the Appalachians: latest Hemphillian to Early Blancan of Gray Fossil Site, Tennessee

“…Recent assessment of the mammalian fauna suggests an age of 4.9 to 4.5 Ma for the GFS ( Samuels, Bredehoeft & Wallace, 2018 ). This suggestion brings the maximum age of the GFS to be in line with that of the Palmetto Fauna of Florida, which is interpreted to be 5.0–4.5 Ma ( Tedford et al, 2004 ; Webb et al, 2008 ).…”

“…The GFS, located in eastern Tennessee ( Fig. 1 ), is one of the few localities in the eastern United States that represents the latest Hemphillian (Hh4) to earliest Blancan ( Wallace & Wang, 2004 ; Samuels, Bredehoeft & Wallace, 2018 ). An oak-hickory forest surrounded the approximately 2.6–3.5 ha lacustrine deposit, which has a maximum depth of 42 m; the GFS is comprised of up to eleven paleosinkholes within the Cambrian to Ordovician dolostone of the Knox Group ( Shunk, Driese & Clark, 2006 ; Whitelaw et al, 2008 ).…”

“…For a full review of the geology of GFS see Shunk, Driese & Clark (2006) and Shunk et al (2009) . Early descriptions from the GFS constrain the site to 7 to 4.5 Ma, based on the presence of Teleoceras and Plionarctos , but a recent description of Gulo sandorus from the site included a list of additional fauna which suggest an lower age limit of approximately 4.9 Ma ( Wallace & Wang, 2004 ; Samuels, Bredehoeft & Wallace, 2018 ). This diverse fauna and flora from this site appears to suggest that the oak-hickory forest surrounding the lacustrine system was a refugium for otherwise disappearing taxa due to the spread of grasslands throughout other regions of the United States ( Wallace & Wang, 2004 ; DeSantis & Wallace, 2008 ).…”

Mesowear Analysis of the Tapirus polkensis population from the Gray Fossil Site, Tennessee, USA

“…Both flora and fauna from the site are wellpreserved and highly diverse (ex. Parmalee et al, 2002;Wallace and Wang, 2004;Mead et al, 2012;Zobaa et al, 2011;Ochoa et al, 2012;2016;Worobiec et al, 2013;Samuels et al, 2018). Macro-and microfossils record a forest flora, which is interpreted as dominated by oak (Quercus), hickory (Carya), and pine (Pinus), along with an understory composed of various herbaceous taxa (Ochoa et al, 2016; and references therein).…”