New Paleogene Notohippids and Leontiniids (Toxodontia; Notoungulata; Mammalia) from the Early Oligocene Tinguiririca Fauna of the Andean Main Range, Central Chile

Abstract

Here we describe three new notohippid notoungulate species from the early Oligocene-aged Tinguiririca Fauna (Tinguirirican SALMA), recovered from volcaniclastic deposits of the Abanico Formation in the central Chilean Andes, two of which are known from material sufficiently complete to warrant formal naming. These include Eomorphippus bondi, sp. nov., a form of moderate size distinguished by hypsodont incisors and cheekteeth, as well as distinctive proportions of the upper incisors. A closely similar but more diminutive form is described as Eomorphippus neilopdykei, sp. nov. A third previously unrecognized notohippid in the Tinguiririca Fauna, best represented by a large, low-crowned, lower incisor battery, almost certainly represents a new taxon, but remains too fragmentary to warrant naming now. We also propose a new binomial for a previously named notohippid, ?Eomorphippus pascuali, originally described from Gran Barranca in Argentina but which is now also recorded in Chile. This taxon, here named Rosendo pascuali, is markedly less hypsodont than E. bondi and E. neilopdykei and retains lingual cingula on at least p4-m1. As least one leontiniid notoungulate occurs in the Tinguiririca Fauna, Termastherium flacoensis, gen. et sp. nov., best represented by two partial upper cheek toothrows and a tentatively referred maxillary fragment bearing three deciduous teeth. Collec-

New Paleogene notohippids and leontiniids (Toxodontia, Notoungulata, Mammalia) from the early Oligocene Tinguiririca Fauna of the Andean Main Range, central Chile

“…The holotype has previously been referred to as Eomorphippus n. sp. (Wyss et al, 1994) and Eomorphippus undesc. sp., near E. obscurus (Flynn et al, 2003).…”

“…Nevertheless, the record of Eomorphip¬ pus from Canadon Blanco became the primary basis for regarding this taxon as characteristic of the Mustersan. In view of the suite of taxa cooccurring in the temporally cohesive Tinguiririca Fauna of Chile, most of the specimens from Canadon Blanco are now regarded as pertaining to a single fauna, one roughly coeval with that Chilean fauna (Wyss et al, 1994).…”

“…Signifi¬ cantly, the horizon producing E. obscurus was the highest fossiliferous level in Feruglio's section, meaning that this specimen likely originated from a stratigraphic level chronologi¬ cally equivalent to Ameghino's APS (presumably Ameghino and Feruglio's sampling localities at the Gran Barranca did not coincide exactly). Three different collectors (Ameghino, Fer¬ uglio, and Simpson) thus independently recovered E. obscurus from the highest levels of beds once considered Mustersan, but that are now regarded as pertaining to the Tinguirirican SALMA (Wyss et al, 1994;Bond et al, 1996Bond et al, , 1997Kay et al, 1999;Flynn et al, 2003;Gelfo et al, 2009). This age inference is supported by recent studies at Gran Barranca that have documented Eomorphippus only at level GBV-4 ("La Cancha"), an interval referred to the Tinguirician SALMA (Lopez et al, 2010) (see also : Re et al, 2010;and Dunn et al, 2013).…”

“…Diagnosis: As for E. obscurus and E. bondi, but differing from those species mainly in much smaller size. Description: Eomorphippus neilopdykei, identified as "notohippid new taxon B" by Wyss et al (1994) and as "undescribed taxon B" by Flynn et al (2003), is currently known only from lower teeth. E. neilopdykei is nearly identical in all comparable morphological details to E. bondi, except that it is much smaller at only slightly greater than half the size of the latter species.…”

“…The Tinguirirican is currently regarded as temporally interposed between the Mustersan (late Eocene) and Deseadan (late Oligocene-early Miocene) intervals of the classical SALMA sequence, given that the Divisaderan, originally considered to precede the Tinguirirican, has recently been shown to be invalid as it represented a mixed assemblage of demonstrably older (mainly Casamayoran) and younger (Deseadan to Santacrucian) taxa (Cerdeno et al, 2008;Lopez, 2008Lopez, , 2010Lopez and Manassero, 2008). Following a preliminary accounting (Wyss et al, 1994), various components of the Tinguiririca Fauna have been described in detail elsewhere, including its marsupials (Flynn and Wyss, 1999), interatheriids (Hitz et al, 2000(Hitz et al, , 2006, archaeohyracids (Croft et al, 2003;Reguero et al, 2003), tardigrades (McKenna et al, 2006), dasypodids (Carlini et al, 2009), rodents (Bertrand et al, 2012), and notostylopids and basal toxodontians (Bradham et al, 2015). Here we build on this documenta¬ tion, describing the faunas diverse but sparsely represented notohippids and leontiniids.…”