SYSTEMATIC PALEONTOLOGY
(continued)

? Superfamily Bovoidea Gray 1821
Family Incertae sedis

 Genus Palaeohypsodontus Trofimov 1958

 Diagnosis

Hypsodont molars, preentocristid and prehypocristid joining post postmetacristid and postprotocristid very early in wear, small metastylid, strong entostylid, and salient “goat-fold,” metaconid and entoconid slightly oblique with an embayment in the lingual wall between metaconid and entoconid.

Palaeohypsodontus zinensis Métais, Antoine, Marivaux, Welcomme, Ducrocq 2003

Diagnosis

Large (estimated m2-m3 length: 3.5 cm) and hypsodont (height:width ratio at least 2:1 in lower m1) species of genus. With very small metastylid forming vertical rib persisting through early wear; strong, projecting entostylid; preentocristid and prehypocristid joined in early wear by a secondary spur from the preentocristid; very strong “goat-fold” (after Métais et al. 2003).

New Material

Locality Z 121: Z 65, fragment of a right upper molar; Z 241, right mandible with m1;

Locality Z 142: Z 2075, right mandible with heavily damaged crowns of p3-m2.

Localities and Age

Locality Z 142 is in the lower unit of the Chitarwata Formation, while Locality 121 is in the lower part of the Vihowa Formation. The localities have estimated ages of ca. 25 and 18.5 Ma, respectively (Lindsay et al. this issue). The type material of the species is from the J2 level of the “Bugti Member” in the Chitarwata Formation and was assigned a Late Oligocene age (Métais et al. 2003).

Description

Lower Dentition. Z 2075 (Figure 14.1-14.2) is a poorly preserved mandible with most of the enamel spalled from the crowns. The teeth appear to have been in middle wear. Specimen Z 241 (Figure 14.3-14.5) is a right mandible fragment with a well-preserved m1 in early wear, and the posterior root of p4 and anterior root of m2. The p3 of Z 2075 was a relatively long tooth, but crown details are not preserved. The p4 is also relatively long and has a few crown details preserved. It has a weak labial incision, compressed posterior heel, and a long and simple anterior crest with an antero-lingually directed paraconid. The metaconid is broken, but the preserved base indicates it was a large cusp. The entoconid and entostylid are both transverse, with the basin between them lingually closed.

The m1 of Z 241 is hypsodont with smooth enamel. The labially and lingually flattened metaconid and entoconid are slightly oblique to the long axis of the tooth and separated by a lingual embayment. The protoconid and hypoconid are selenodont. The premetacristid merges with the preprotocristid, while the posthypocristid contacts the postentocristid, closing off the posterolingual end of the median valley and forming a projecting entostylid. The wear traces of the postmetacristid and postprotocristid connect, and both in turn join with the trace of the preentocristid. The preentocristid and prehypocristid are joined by a spur that presumably originated on the anterolabial face of the preentocristid and together with the postmetacristid and postprotocristid form a small chimney-like structure. There is no sign of a “Palaeomeryx‑fold” nor ectostylid, but there is a very small metastylid closely appressed to the metaconid and just lingual to the descending trace of the postmetacristid. The anterior cingulum (mesial cingulum of Métais et al. 2003) is very tall and strong, forming a “goat-fold” on both labial and lingual sides of the tooth. There is no posterior cingulum.

The badly damaged molars of Z 2075 preserve few details. Both are hypsodont, as evidenced primarily by the deep medial valleys of the trigonid and talonid, and on m2 there is a tall “goat-fold.” (The m1 is too damaged to determine the presence or absence of this feature.) The m2 has a low ectostylid and both molars have vestiges of posterior cingula. The prehypocristid of the m2 is isolated from both the preentocristid and the trigonid cusps, and there is no sign of an accessory spur on the preentocristid.

Upper Dentition. Z 65 is the lingual half of a small pecoran upper molar. It is a close match in size for the associated mandible Z 241 but otherwise has no diagnostic features.

Comparisons

Horncores are not known for this species, but other hypsodontines are known to have horncores and we therefore refer it to the Bovoidea. Because the relationships between hypsodontines and bovids are uncertain, we have not assigned it to a family.

Palaeohypsodontus zinensis differs from other species of Palaeohypsodontus in its larger size, greater degree of hypsodonty, and more salient “goat fold.” It differs from Hanhaicerus qii Huang 1985 in being much more hypsodont, with a more reduced metastylid and isolated prehypocristid.

Palaeohypsodontus zinensis differs from advanced hypsodontines such as Kubanotragus Gabunia 1973 or Hypsodontus Sokolov 1949 in being distinctly less hypsodont, and in having oblique lingual conids, a lingual embayment between metaconid and entoconid, and a connection of the prehypocristid to the preentocristid, rather than directly to the postprotocristid.

Namibiomeryx senuti Morales, Soria, Pickford 1995 is similar to Palaeohypsodontus zinensis in its degree of hypsodonty and in having relatively long premolars. However, the lingual wall of the lower molars in Namibiomeryx senuti is relatively flatter without a deep embayment, there is no strong development of an anterior basal cingulum, and the hypoconid is separated from the entoconid both anteriorly and posteriorly. Early bovids, as represented by material from the Vihowa and Kamlial formations of Pakistan, are much lower crowned than the nearly contemporary specimen of Palaeohypsodontus zinensis and lack strong “goat folds,” as well as the precocious fusion of the prehypocristid to the trigonid complex. Early bovids also have more distinct metastylids and weaker entostylids.

Discussion

The two mandibles referred to this species differ from each other. We have placed them together on the basis of the apparent hypsodonty, salient “goat-folds,” and similarity in size. However, the presence of an ectostylid and posterior cingula on Z 2075, as well as the conformation of the preentocristid, suggests the Z 142 mandible belongs to a different taxon. Z 2075 is considerably older than the other Zinda Pir specimens, and may also be much older than the type specimen of Palaeohypsodontus zinensis from near Dera Bugti (Welcomme et al. 2001; Métais et al. 2003; Lindsay et al. this issue).

There are also postcranial remains of a small pecoran from the base of the Potwar sequence at Locality Y 747 (ca. 18.3). While morphologically similar to Bugtimeryx and Progiraffa, the fossils are larger than Bugtimeryx pilgrimi and much smaller than Progiraffa exigua. They are an appropriate size for Palaeohypsodontus zinensis but are not associated with any hypsodontine dental material, and we therefore do not refer them to this taxon. Whatever the identity of this small pecoran, it clearly represents an additional species in the Kamlial Formation.

 Superfamily Bovoidea Gray 1821
Family Bovidae Gray 1821

Unnamed Genus and Species

Material

Locality Z 110: Z 21, right mandible with m2 hypoconid and roots of m3.

Locality Z 120: Y 46299, Fragment of a left horncore; Y 46300 and Y 46301, horncore fragments, probably part of Y 46299; Y 46302, edentulous skull, probably part of Y 46299; Z 54, upper molar; Z 60, left distal humerus; Z 61, proximal left metatarsal; Z 219, right maxilla with P3-M3; Z 221, complete left astragalus; Z 226, distal metapodial; Z 246, left M3; Z 247, left m1 or m2; Z 248, left upper molar; Z 249, left P4; Z 250, left P3; Z 251, left I3; Z 253, right p3; Z 254, fragment of upper premolar; Z 593, fragment of p4.

Locality Z 122: Z 108, incomplete right cuboid-navicular; Z 117, proximal epiphysis of a proximal phalanx.

Locality Z 205: DGK 219, right mandible with m1 or m2.

Locality Z 211: DGK 146, left cuboid-navicular.

Localities and Age

Only material from the Zinda Pir Dome area is listed above. The localities span approximately 19.5 to 16 Ma (Lindsay et al. this issue). The identification of some of the material is questionable, especially the mandible from Locality Z 110, which is from the oldest site. However, the skull, horncore, and dental material from Locality Z 120 are incontestable and, at approximately 18.5 Ma, it is still one of the oldest known bovids. Additional material attributed to the Early Miocene bovid Eotragus noyi is from the base of the terrestrial sequence on the Potwar Plateau and is approximately 18.3 Ma (Solounias et al. 1995). Ginsburg et al. (2001) reported Eotragus from level 6 at Dera Bugti, attributing an Early Miocene age to it.

Discussion

The Vihowa horncores are illustrated in Solounias et al. (1995, fig. 5), where they are attributed to an unnamed species different from Eotragus noyi. Description of the unnamed species will be included in a general revision of Siwalik bovids. It is a small (m2-m3 length: ~ 2.5 cm) species with flattened, keeled horncores.