Afromeryx grex

Miller, Ellen R., Gunnell, Gregg F., Gawad, Mohammad Abdel, Hamdan, Mohamad, El-Barkooky, Ahmed N., Clementz, Mark T. & Hassan, , 1914, Anthracotheres from Wadi Moghra, early Miocene, Egypt, Journal of Paleontology 88 (5), pp. 967-981: 974

publication ID

10.1666/13-122

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http://treatment.plazi.org/id/50196681-956E-79D4-D64A-3DF0F3BB14B1

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scientific name

Afromeryx grex
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Type.-M 15021, sub-adult left dentary, edentulous symphysis, crowns of p2-m3, m3 in crypt (Table 1, Fig. 5A).

Diagnosis.-Differs from A. zelteni  in being larger (m2 area >60% larger), having a much longer molar series length (m1-3 ~ 108 mm in A. grex  versus ~58 mm in A. zelteni  ), p4 with a well-developed talonid; differs from A. palustris  ( n. sp. below) in having smaller premolars (~25-30%), lower premolars with pustulate anterior and posterior crests, lowers premolars with distinct and elevated cingulids, p2 lacks development of an anterior crest.

Etymology.-"Grex," Greek for flock or herd, in recognition of the herd behavior of many artiodactyls.

Occurrence.-Early Miocene, Wadi Moghra, Egypt.

Description.-Description of holotype specimen and occlusal details of teeth are available in Pickford (1991).

Remarks.- Afromeryx grex  resembles the better known A. zelteni  from Gebel Zelten, in having an unfused symphysis, dental formula 3.1.4.3; no specializations of the anterior dentition, i1-3 are small spatulate teeth; no i3-c diastema, c-p1 diastema present, p1 single rooted, and mental foramina below i1, p2, p4. in all known comparable parts, A. grex  seems to be a larger version of A. zelteni  . As Pickford (1991) noted, the presence of pustulate crests on the premolars in species of Afromeryx  is reminiscent of the condition seen in Gonotelma shabazi  from the Bugti Beds, early Miocene, Pakistan, although what this resemblance means regarding the extent of a possible relationship between the two taxa has not been explored.

The taxonomic history of Afromeryx  is complex. Pickford (1991) named Afromeryx africanus  on the basis of a right dentary with roots of p3, p4-m3 (CGM 30762), and attributed one additional sub-adult mandibular specimen (M 15021) to this species. The type specimen of A. africanus  had previously been recognized as representing Brachyodus africanus  (Andrews, 1899), but Pickford (1991) stated that, ‘‘ The material does not closely resemble Brachyodus, the molars and premolars being bunodont, the jaw being short with an unspecialized symphyseal region’’ (1991, p. 1503). In terms of size and degree of bunodonty, we find that CGM 30762 cannot be distinguished from members of Brachyodus depereti and so we have assigned the specimen to that taxon. In addition, it is unknown how the assessment was made that CGM 30762 represented a taxon with a short jaw and an unspecialized symphyseal region. The dentary is broken in front of p3 and so is missing the anterior portion of the jaw. This is critical because many of the features that distinguish anthracothere species are located in the anterior dentition. For example, species of Afromeryx  have an unspecialized symphyseal region (i1-3 small, spatulate teeth, no i3-c diastema, p2 single-rooted ), whereas species of Brachyodus show a number of extreme specializations (suppression of i1-2, i3 tusk-like, peglike canine, long diastema). The fact that the holotype of A. africanus  designated by Pickford (1991) is a dentary with only roots of p3 and crowns p4-m3 means that most of the key diagnostic criteria of Afromeryx  are not visible on this specimen.

Therefore, we feel that CGM 30762 cannot serve as the holotype of a species of Afromeryx  . To rectify this situation we have reassigned CGM 30762 to Brachyodus depereti where it fits comfortably based on size and known morphology and we have assigned M15021 as the holotype and currently only know specimen of a new species of Afromeryx  , A. grex  .