Vera—Eocene archeopithecids from Patagonia


1277


Table 3. Body masses (mean values in kg) for Archaeopithecus rogeri and notopithecids based on different authors (dataset taken from Vera, 2013b). FLML, first lower molar length; SUML, second upper molar length; LMRL, lower molar row length; SLML, second lower molar length; TLML, third lower molar


length; Li1, transverse width of the tibial trochlea; Li2, proximodistal length of the lateral trochlear ridge of the tibial trochlea; Li5, proximodistal length of the astragalus; Li9, dorsoventral thickness of the medial part of the astragalus; Ar1 = Li1 x Li2; Ar3 = Li1 x Li9.


Janis (1990)


Taxon/allometric equation Archaeopithecus rogeri


n sd


Notopithecus adapinus n


sd


Antepithecus brachystephanus n


sd Transpithecus obtentus Guilielmoscottia plicifera 21 79 47


0.40 1.06


0.38 1.71


n8 9 sd


0.51 1.75


0.48 2.63


n11 sd


0.67 18


1.25 0.32


63 12


0.87 0.21


1.53 0.35


1.35 0.27


1.92 3


0.34


1.36 2


0.41 0.67


22


0.18 0.99 8


0.14 1.30 3


0.18 1.83 8


0.27 21 79


1.75 0.38


1.35 0.37


47


1.97 0.44


2.01 8


0.42 2.76


11 0.55


and consisting of a maxillary fragment with six teeth, here recognized as right P1–M2, coming from the Casamayoran levels of Sarmiento Formation (Patagonia, Argentina), but without specific locality information. Originally, Ameghino described upper premolars and molars for this species, giving the P1–M3 length (27 mm), and he also described a mandible fragment, providing several dimensions. Unfortunately, this


mandible is presently lost and only the maxilla was originally figured (Ameghino, 1897, fig. 8; 1904, fig. 402). Although he described the complete upper molar series, the M3 is missing in


the maxilla. It is worth noting that M3 is dotted in Ameghino’s figure, which means that this molar was always absent. Although MACN-A 10816 is poorly preserved, it is pos-


sible to distinguish the following features: triangular upper premolars; low and well-developed mesial cingulum on P2–4 and upper molars; very undulating ectoloph in P2–4; upper molars wider than longer (LLD>MDD); and deep lingual sul- cus in M1–2, very shallow in P4, and absent in P2–3. This combination of features is observed in AMNH FM 28782 (Acropithecus rigidus sensu Simpson, 1967b), MACN-A 10813 (lot catalogued as Archaeopithecus rigidus, see below), and MACN-A 10851a (type of Acropithecus plenus), although the presence of a lingual sulcus in P4 cannot be corroborated in the last specimen. In addition, the measurements of all these specimens are comparable (Table 1). The holotype of the species Archaeopithecus alternans is


the specimen MACN-A 10815 (maxillary fragment with left M1–3; Fig. 2.2), which comes from ‘Oeste de Río Chico’ (Ameghino’s locality from Chubut Province, Fig. 1; Simpson, 1967a). Ameghino (1901, p. 359) described Archaeopithecus alternans as a larger species than A. rogeri and provided the length of M1–3 (14mm). M1 of MACN-A 10815 is squarer than that of MACN-A 10816 (A. rogeri), which is more rec- tangular certainly due to its greater degree of wear, although the length in both is practically the same (Table 1). Indeed, dimensions of M2 and M3 in MACN-A 10815 match the M3s of MACN-A 10850 (type specimen of Acropithecus tersus, see below) and of other specimens, such as MLP 79-I-17-20 (Table 1). In addition, MACN-A 10815 (Fig. 2.2) is morpho- logically very similar (fossettes configuration, undulated


Scarano et al. (2011) 12 77


1.43 0.29


1.03 0.25


44 12


1.39 0.21


1.52 0.26


12


2.14 0.40


10 64


2.57 0.45


1.99 0.35


33 13


2.40 0.35


3.17 0.28


11


3.20 0.80


18 63


1.51 0.31


12


0.22 1.79


0.34 1.61 9


0.26 2.15 3


0.31


ectoloph, lingual sulcus on molars, mesial and distal cingula) to MACN-A 10813 (Fig. 2.3, 2.6, 2.10). Archaeopithecus rigidus was defined by Ameghino (1901,


p. 359) basically by its larger size compared with A. rogeri and by having squared upper molars with faintly undulating labial face and lingual sulcus. Ameghino also provided the length of P2–M3 (30mm). The material catalogued as type of A. rigidus has the number MACN-A 10813 (Fig. 2.3–2.11) and it is a lot with seven maxillary fragments and two isolated teeth, coming from ‘Oeste de Río Chico’ (Fig. 1). The lot consists of:MACN- A 10813a, maxillary fragment with left P2–M2 (Fig. 2.3); MACN-A 10813b, maxillary fragment with left P4–M2 (Fig. 2.4); MACN-A 10813c, maxillary fragment with right P4–M2


(Fig. 2.5; P4, presently broken, probably corresponds to that figured by Ameghino, 1904, fig. 404); MACN-A 10813d, maxillary fragment with right M1–3 (Fig. 2.6); MACN-A 10813e, maxillary fragmentwith right P1–3 (Fig. 2.7);MACN-A 10813f, maxillary fragment with right P4 (Fig. 2.8; similar to the P4 pictured by Ameghino, 1904, fig. 403); MACN-A 10813g, maxillary fragmentwith rightM1–2 (Fig. 2.9);MACN-A10813h, rightM1orM2(Fig. 2.10); andMACN-A10813i, left P4 (Fig. 2.11; this matches the P4 figured by Ameghino, 1904, fig. 405). Simpson (1967b, p. 65) identified the same number of


specimens in lot MACN-A 10813; he selected the maxilla, here named MACN-A 10813b, as the lectotype of Archaeopithecus rigidus and mentioned that the other specimens in the lot could all be syntypes. Bearing in mind that Ameghino (1901) pro- vided only the length of a P2–M3 series, and there is not such a series represented among the specimens in lotMACN-A 10813, two explanations are possible: the maxilla on which Ameghino based his description (and measurements) is lost or, more likely, Ameghino used several elements in combination, as he did for Archaeopithecus rogeri (see above). Whatever was the case, the decision of the first reviewer (Simpson, 1967b) is here accepted and MACN-A 10813b (Fig. 2.4) is considered the lectotype of Archaeopithecus rigidus. Specimen MACN-A 10813b (Fig. 2.4) is characterized by


a narrow mesial cingulum and a high distal cingulum on molars; P4 with very undulating ectoloph and narrow lingual face showing a deep sulcus; and M1–2 with less undulating ectoloph


Tsubamoto (2014)


FLML SUML LMRL FLML SLML TLML SUML Li1 Li5 Ar1 Ar3 Average total 1.47


1.62


1.13 1.80 1.85 1.82 1.82 1 111


1.40 1.68 1.82 2.38


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