Vera—Eocene archeopithecids from Patagonia


AMNH FM 28782 (Fig. 3.5), here identified as most anterior lower incisors and/or canine. Two of them are conical and sin- gle-rooted; they do not have any lingual or labial sulci, unlike in notopithecids. One tooth (2.0 ×1.6mm) is a bit more labiolin- gually flattened than the other (1.9 × 1.8mm) and has a beveled distal crest. The third tooth is smaller and has a very low crown in comparison with the other teeth; its tip is rounded; it has a slightly concave internal face, whereas the external is convex. According to the size of the preserved alveolus in the lower jaw AMNH FM 28782, i1 is the smallest of the series, and c is approximately equal in size to i3. Their position demonstrates that the implantation of incisors is non-procumbent, which differs from Notostylops. The premolars are characterized by having the trigonid


Lower dentition.—There are three isolated teeth in lot


longer than the talonid and a well-developed protostylid fold distally extended (Fig. 3.6), as described for p3–4in Transpithecus (Vera, 2012a), but contrasting with Notopithecus, Antepithecus, Notostylops, and oldfieldthomasiids. Molars, instead, have trigonid much shorter than premolars and a longer talonid; the trigonid is particularly narrow and labially convex, with a lingually inclined protolophid. Occasionally, a very low conulid behind protoconid, between trigonid and talonid, is present on molars. The p1 was not identified in the sample. On p2 (Fig. 3.6),


the trigonid is narrower than the talonid, with two crests forming aV; the protolophid is mesiolingually very inclined; and the metalophid ends in a distally directed metaconid. The mesiolingual cingulid is narrow and low. The talonid is trian- gular in shape. The distal cingulid is low and wide, limiting a deep pit. The p3–4 are similar to each other, premolariform (Fig. 3.6;


Table 2), differing from molars as the homologous teeth in upper series (see above). The metalophid is a much-curved crest, and the metaconid is, in consequence, distally displaced in a postmetacristid; thus, the latter approaches to the entolophid, forming a fossettid in the talonid when worn. Thiswell-developed


postmetacristid is shared by notopithecids, but not by old- fieldthomasiids, henricosborniids, and notostylopids. The cristid oblique touches the metalophid at the middle point of the labial face. The protostylid can be absent (Fig. 4.15); such variability was also observed in Transpithecus (Vera, 2012a).There is awell- developed and low mesial cingulid, which merges with the pro- tolophid and forms a long linguodistally oriented crest. The p3 of AMNH FM 28801 (Fig. 4.16) has an unworn conulid (entostylid) in the talonid basin, in contact with the entolophid; with wear, this conulid merges with the entolophid, giving it the mesial expansion observed on p4 and the molars; with more advanced wear, this expansion reaches the metaconulid, isolating a circular fossettid (Fig. 4.14). Comparing to the wear stage of premolars of AMNH FM 28782 (Fig. 3.6; Table 2), p2 is less worn than p3, and the latter has less wear than p4, although the difference in wear is more evident between p2–3thanp3–4.Based on this observation, it is assumed that p2 is the last premolar to erupt, and the sequence of eruption can be established as p4, p3, and p2. The same pattern was described for notopithecids, the henricosborniid Henricosbornia, some interatheriines (Vera and Cerdeño, 2014; Vera, 2016), and the hegetotheriid Paedotherium (Cerdeño et al., 2017).


1287 The m1 and m2 are similar to each other, and it is difficult


to differentiate them when they are isolated because it occurs with upper molars. A short-lived hypolophid is present (Fig. 4.16) and a tiny lingual cingulid connects hypolophid with entolophid, isolating a distal fossettid on the talonid (Fig. 4.17; SW = 1 and 2 in Fig. 5.3). In older individuals, how- ever, the hypolophid and fossettids ‘disappear’ due to themerging of hypolophid and entolophid, and the talonid becomes sub- circular (Fig. 4.15; SW = 3 in Fig. 5.3). The fossettid located between entolophid and hypolophid is more ephemeral than the central fossettid placed between metalophid and entolophid (Figs. 3.6, 4.14, 5.3). Molars have a well-developed entostylid, which is shared onlywith Pleurostylodon. The entostylid is highly variable in shape according to wear stage, being either hook- shaped (Fig. 4.18) or bilobed (Fig. 4.19). The m3 differs from m1–2 in the talonid. It is longer, has a


long and well-developed hypolophid and a labial sulcus (hypo- flexid), which is deeper than in other Eocene notoungulates


(except Henricosbornia). Although absent in some individuals, there is a low lingual cingulid uniting entoconid and hypolophid and forming a distal fossettid, which is more evident when worn; differing from m1–2, it is a deeper and long-term fossettid (Fig.4.20).Asinm1–2, the entostylid touches the metaconid and forms a mesial fossettid on the talonid; however, this entostylid is wider and can have small extra crests (Fig. 4.22). In some speci- mens (Fig. 4.21, 4.23), there is a small and low lingual cingulid that closes the valley between trigonid and talonid. In younger individuals (Fig. 4.24), trigonid and talonid are occlusally sepa- rated, but with wear the cristid oblique touches the metalophid at mid point. Molars have a short paralophid that merges in early stages of wear with the mesial cingulid, forming a long crest (Figs. 4.15, 4.16, 4.18, 5.3). Postcranium.—Specimen AMNH FM 28895 includes the


right Mc II and Mc III in anatomical connection (Fig. 6.1–6.3), an isolated metapodial (Fig. 6.4–6.7), a fragment of phalange, and a fragment of left ulna (Fig. 6.8, 6.9). The metacarpals are poorly preserved. Mc II is distally incomplete, but it would be shorter than Mc III (Fig. 6.1; Table 4); the proximal articular surface of Mc II is deeper and wider than that of Mc III (Fig. 6.2); the proximointernal face is broken. Mc III has a laterally compressed proximal half (AP>T),


an anteroposteriorly flattened distal half (AP<T), and is approximately square at the midpoint (Fig. 6.1; Table 4); there is a concave proximoexternal facet for Mc IV, formed by two lunate sections, with the anterior being larger than the posterior part (Fig. 6.3); the proximal articular surface is asymmetrically triangular. The length of Mc III is comparable to the dimensions of the Mc III of Colbertia magellanica (Bergqvist and Fortes Bastos, 2009). Dimensions of Mc II–III (Table 4) are larger than those reported by Vera (2012b, table 4) for the metapodials of Notopithecus adapinus. The isolated metapodial AMNH FM28895 is significantly


shorter than Mc II–III (Table 4). This difference in size occurs, for example, among metacarpals of the Interatheriinae Protypotherium, Miocochilius, and Federicoanaya, in which Mc V has almost half the length of Mc III (Sinclair, 1909; Stirton, 1953; Hitz et al., 2008). Based on this comparison (Eocene associated metapodials are practically unknown) and by association with the other metacarpals present in the lot


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