Victorlemoinea longidens Ameghino (1901)

Tejedor, Marcelo F., Goin, Francisco J., Gelfo, Javier N., López, Guillermo, Bond, Mariano, Carlini, Alfredo A., Scillato-Yané, Gustavo J., Woodburne, Michael O., Chornogubsky, Laura, Aragón, Eugenio, Reguero, Marcelo A., Czaplewski, Nicholas J., Vincon, Sergio, Martin, Gabriel M. & Ciancio, Martín R., 2009, New Early Eocene Mammalian Fauna from Western Patagonia, Argentina, American Museum Novitates 3638, pp. 1-43 : 23-25

? Victorlemoinea longidens Ameghino (1901)

An incomplete right lower molariform (p4 or m1 LIEB-PV 1614) was collected in Laguna Fría. This bicrescentic tooth is similar in size and morphology to Victorlemoinea longidens . Victorlemoinea labyrinthica and V. longidens were collected in Vacan levels of Patagonia ( Simpson, 1967a). The oldest record of the Family Sparnotheriodontidae is Victorlemoinea prototypica Paula Couto (1952) , from the Itaboraian of Brazil, and its youngest record is Phoradiadius divortiensis Simpson et al. (1962) from the Divisaderan of Mendoza, Argentina.

Order Notopterna ( Soria, 1984b) Family? Amilnedwardsiidae ( Soria, 1984a)

This family includes small bunodont ungulates with poorly developed ectoloph and paraloph, and a lophoid metaconule. The Casamayoran genera Amilnedwardsia , Rutimeyeria , and Ernestohaeckelia , named by Ameghino (1901), were referred by the author to this family as taxa of generalized morphology. These genera are almost exclusively represented by upper molars, with the exception of a lower molariform from the Casamayoran of Cañadón Hondo (Chubut Province), mentioned by Soria (1984b) as referrable to Amilnedwardsiidae .

Gen. et sp. indet. H

There are two left mandibular fragments from Laguna Fría, one with p2 and p3 partially broken, and p4–m2 (LIEB-PV 1616), and a second specimen with p3–4 (LIEB-PV 1617). They are selenodont and bicrescentic with the entoconid contacting the hypoconulid. Comparison to other lower molariforms mentioned by Soria (1989) indicates that these specimens should be regarded as Gen. et sp. indet. members of the Family Amilnedwardsiidae . However, given their fragmentary nature and the similarities between the Amilnedwardsiidae and the Notopterna Indaleciidae , they could also be referred to the latter family.

Order Notoungulata ( Roth, 1903) Family Henricosborniidae ( Ameghino, 1901)

This family has several generalized dental characters placing them in a basal position with respect to other notoungulates. As G.G. Simpson (1948: 147) said:

The henricosborniids are clearly the most primitive known notoungulates, and they nearly fulfill all the theoretical requirements for a generalized type ancestral to all others known.

Traditionally, species referred to this family characterize both the Riochican and Vacan faunal associations.

Henricosbornia lophodonta Ameghino (1901)

Figure 7E

Maxillary and mandibular fragments referred to the Family Henricosborniidae are abundant in both localities of Paso del Sapo, with complete series of premolars and molars, as well as isolated teeth. The presence of a strong metacone, a convex mesostyle area in the upper molars, and a distinct hypoconulid in m1–2 relate these specimens to Henricosbornia lophodonta , a typical taxon in several Vacan levels, but also recorded in the upper levels of the Riochican of Bajo Palangana, Chubut Province. In Paso del Sapo, additional mandibular fragments are doubtfully assigned to the genus Henricosbornia , morphologically more related to H. lophodonta Ameghino (1901) but closer to the size of H. waitehor Simpson (1935a) .

Other fragmentary materials with simpler ectolophs, a different configuration of the metaloph, and smaller size are here referred as cf. Henricosbornia .

Othnielmarshia lacunifera Ameghino (1901)

Figure 7F

A right maxillary fragment with complete M1–3 (LIEB-PV 1618, fig. 7F) was collected in Laguna Fría. These molars have a strong labial cingulum and a shortened crochet in M1, vestigial in M2, and absent in M3. It is referred to Othnielmarshia lacunifera . On the other hand, there are several isolated lower molars with the entoconids clearly separated from the hypoconulids that may be also attributable to this species. The type of O. lacunifera comes from ‘‘west of Río Chico’’, and thus is Vacan in age ( Simpson, 1967a) and Simpson himself collected materials in Cañadón Vaca.

Family Notostylopidae ( Ameghino, 1897)

Notostylopids acquired a specialized, styliform incisors and diastema during their early stages of their evolution, giving them a rodentlike appearance. In Patagonia, this family is known from the Riochican through the Mustersan, but the latest representatives were collected in the Tinguirirican of central Chile (referred to the late Eocene–early Oligocene by Flynn et al., 2003). They were never diverse but were the most abundant ungulates during the Vacan and Barrancan subages. Three genera are described for the Paso del Sapo localities below.

Edvardotrouessartia sola Ameghino (1901)

Figure 7G

Two maxillary fragments were collected at Laguna Fría, one with broken P2–4 (LIEB-PV 1619; fig. 7G), and the other with incomplete P4 (LIEB-PV 1620). The premolars show a flat paracone and, in labial view, the characteristic pyramidal shape of Edvardotrouessartia sola . Specimens of E. sola came from ‘‘west of Río Chico’’ ( Simpson, 1967a, b), and there are excellent collections also from Cañadón Vaca in the Museo de La Plata and Museo de Mar del Plata. Thus until now, E. sola was exclusive to the Vacan.

Figures

Fig. 7. South American native ungulates from Laguna Fría (LF) and La Barda (LB). A, LIEB-PV 1612, Didolodontidae, gen. et sp. nov., right m2–3; B, Asmithwoodwardia subtrigona, LIEB-PV 1636, left M2; C, Asmithwoodwardia subtrigona, LIEB-PV 1617, right m2; D, Spartnotheriodontidae, Gen. et sp. indet. G, MLP-66-V-12-2, right maxillary fragment with three molariforms (P4–M2?) (LF); E, Henricosbornia lophofonta, LIEB-PV 1633, right maxilla with P4–M2 (LB); F, Othnielmarshia lacunifera, LIEB-PV 1618, right maxilla with M1–3 (LF); G, Edvardotrouessartia sola, LIEB-PV 1619; right maxilla with P2–4 (LF); H, Isotemnus sp., LIEB-PV 1646, right maxilla with P4–M3 (LF); I, Isotemnus sp., LIEB-PV 1659, left m2 (LF). Scale bar 5 1 mm.