New record of Pampahippus secundus (Mammalia, Notoungulata) from the Upper Lumbrera Formation, Eocene of northwestern Argentina

GARCÍA-LÓPEZ, DANIEL A.; DERACO, VIRGINIA; ROUGIER, GUILLERMO W.; PAPA, CECILIA DEL; BABOT, JUDITH; BERTELLI, SARA; HERRERA, CLAUDIA M.; GIANNINI, NORBERTO P.

JOURNAL OF VERTEBRATE PALEONTOLOGY

SOC VERTEBRATE PALEONTOLOGY

Año: 2019

0272-4634

The Paleogene record of notoungulates in northwesternArgentina (NWA) is relatively abundant, including 20 species distributedin 16 genera (Powell et al., 2011; Babot et al., 2017). Fourteenof those 16 genera are recorded only in NWA (Powell et al.,2011; Woodburne et al., 2014b), the exceptions being Colbertia,also present in Itaboraí, Brazil, and Pseudhyrax, a typotherianfound in the Argentinean Patagonia and central Chile (PaulaCouto, 1952; Croft et al., 2003; Bergqvist et al., 2007). Thisfauna is not only restricted geographically but also temporally,given that only a few of these taxa have been recorded in morethan one of the stratigraphic units cropping out in NWA (viz.,Jujuy, Salta, Tucumán, and Catamarca provinces). Thus, mostrecords correspond to single occurrences for each unit, preventingstratigraphic correlations, general comparisons for somefossil-bearing units, and the discovery of biogeographic patterns.Northwestern Argentinean genera are usually monotypicexcept Simpsonotus (two species; Pascual et al., 1978), Pampatemnus(two species; Vucetich and Bond, 1982), and Pampahippus(three species; Bond and López, 1993; Deraco and García-López, 2016; García-López et al., 2017). The latter is remarkablebecause it is recorded in at least two formations, Lower Lumbreraand Quebrada de los Colorados, plus a dubious mention referredto cf. Pampahippus from the Geste Formation (López, 1997).Until now, the aforementioned stratigraphic units have nospecies in common, reinforcing the temporal and regional disjunctdistribution of congeneric species (P. arenalesi and P. secundusfor Lower Lumbrera, and P. powelli for Quebrada de losColorados). Only sebecid crocodiles provide evidence of a temporallycontinuous lineage in these formations (Pol and Powell,2011; Powell et al., 2011).During the last two years, new collecting efforts inMWArecovereda significant and varied amount of fossil vertebrates.We herepresent a new specimen referable to the ?notohippid? Pampahippussecundus from the Upper Lumbrera Formation at the localityof El Simbolar, Salta Province. This record provides newanatomical information for this taxon and expands its biochronfrom Lower Lumbrera to Upper Lumbrera, thereby being thefirst mammal common to both formations. We establish the sedimentologicalsetting of this and previous fossils, describe the newspecimen, and discuss its stratigraphic and biogeographicimplications.