Notoungulate faunas of north-western Argentina: new findings of early-diverging forms from the Eocene Geste Formation

A new Eocene Toxodontia (Mammalia, Notoungulata) from northwestern Argentina

“…Nevertheless, some recent integrative studies have included them (Shockey, 1997;Deraco et al, 2009;Billet, 2011;Garc ıa-L opez and Powell, 2011;Shockey et al, 2012;Garc ıa-L opez and Babot, 2015). At this point, it should be noted that the generalized nature of the notoungulate representatives recorded in Eocene units of northwestern Argentina have proved to be a significant impediment to the resolution of phylogenetic analyses, and in several cases these taxa fall far from the post-Deseadan representatives of their (supposed) family-level groups.…”

“…In northwestern Argentina, the current record of notohippids includes only the early Pampahippus arenalesi. This species occurs in the Lumbrera Formation in Salta Province and possibly the slightly younger Geste Formation (L opez, 1997;Garc ıa-L opez and Babot, 2015).…”

Anatomical and Systematic Study of Proximal Tarsals of Ungulates from the Geste Formation (Northwestern Argentina)

“…The fossils studied herein were recovered from the middle member, which is characterized by the presence of reddish and coarse sandstones and mudstones alternating with lenticular conglomerate levels (Alonso, 1992). Vertebrates recorded for this section include crocodiles, snakes, lizards and an important number of mammals (López, 1997;Goin et al, 1998;Babot et al, 2012;García-López and Babot, 2015). Although fragmentary, notoungulate remains are abundant and species of "Oldfieldthomasiidae", "Archaeohyracidae", Interatheriidae, Notostylopidae, "Isotemnidae" and "Notohippidae" have been recorded López, 1997;Reguero et al, 2008;García-López, 2015;García-López and Babot, 2015).…”

“…Vertebrates recorded for this section include crocodiles, snakes, lizards and an important number of mammals (López, 1997;Goin et al, 1998;Babot et al, 2012;García-López and Babot, 2015). Although fragmentary, notoungulate remains are abundant and species of "Oldfieldthomasiidae", "Archaeohyracidae", Interatheriidae, Notostylopidae, "Isotemnidae" and "Notohippidae" have been recorded López, 1997;Reguero et al, 2008;García-López, 2015;García-López and Babot, 2015). Although the age of the Geste Formation has been extensively discussed and different points of view have been proposed, recent isotopic dating and stratigraphic considerations indicate a middle-late Eocene age for mammal bearing levels (DeCelles et al, 2007;Carrapa and DeCelles, 2008;García-López and Babot, 2015).…”

“…Over the last 30 years, extensive fieldwork in northwestern Argentina resulted in the discovery of significant fossil mammals (e.g., Vucetich, 1980;Bond, 1981;Pascual et al, 1981;Bond and López, 1995;López, 1997;Goin et al, 1998;Babot et al, 2002Babot et al, , 2012Reguero et al, 2008;García-López andPowell, 2009, 2011;Argot and Babot, 2011;Powell et al, 2011;Armella et al, 2014;García-López and Babot, 2015). In this sense, many authors have noted the multiple importance of these northwestern records, including the fact that the most ancient representatives (and in certain cases some of the most basal forms) of different lineages have been found there (Reguero et al, 2008;García-López and Powell, 2011).…”