Afrotragulus parvus (Withworth, 1958)

Sánchez, Israel M., Quiralte, Victoria, Morales, Jorge & Pickford, Martin, 2010, A new genus of tragulid ruminant from the early Miocene of Kenya, Acta Palaeontologica Polonica 55 (2), pp. 177-187 : 181-182

publication ID	https://doi.org/10.4202/app.2009.0087
persistent identifier	https://treatment.plazi.org/id/03D087FF-FFDA-1F37-228D-F99FFB8FF938
treatment provided by	Felipe
scientific name	Afrotragulus parvus (Withworth, 1958)
status

Treatment

Fig. 3 View Fig .

1958 Dorcatherium parvum Withworth, 1958: 11–14 .

2002 Dorcatherium parvum Pickford, 2002: 88 : pl. 1: 2–4.

Type material: Holotype: BMNH M29514 , left hemimandible with m1–m3 (Withworth 1958) . Paratypes: Withworth (1958) does not specify paratypes, and some of the original specimens are not currently located. We consider the specimens from Rusinga localities listed and described by Withworth (1958: tables 5, 6) as the paratypes of the species. We exclude the specimens BMNH 1171.50 (Kathwanga locality) and BMNH R.846.48 (Rusinga locality; see Discussion) .

Referred specimens: BMNH M82689, left hemimandibular fragment with m1–m2; BMNH M82690, hemimandibular fragment with m2; BMNH M82686, left maxillar fragment with P4–M3; BMNH M82687 and BMNH M82688, right astragali (measurements in Tables 1, 2; all from Rusinga localities; see Discussion).

Type locality: Rusinga localities (Kathwanga series, Hiwegi beds, Kiahera series), Rusinga, Western Kenya (Withworth 1958) .

Type horizon: Early Miocene ca. 17.5 Mya (Withworth 1958; Pickford and Senut 2003). Withworth (1958) does not specify a horizon for the holotype specimen.

Emended diagnosis.— Afrotragulus differing from the type species in its larger size and in some morphological characters of the lower molars: shorter post−hypocristid in the m2; weaker posterior cingulid; less vertically developed cristids; less aligned lingual cusps; and entoconid located almost in front of the hypoconid.

Description

Mandible and lower molars.—As noted by Withworth (1958) the mandible of A. parvus is low and narrow as is typical of tragulids. The elongated and narrow lower molars of A. parvus , with their well−marked selenodonty and high cristids are very similar to those of the type species ( Fig. 3A–C, E, F View Fig ). Both the separation between the pre−hypocristid and the anterior lobe and the contact of the pre−hypocristid with the pre−entocristid are very clear. The post−hypocristid in the m2 is not as developed as in A. moruorotensis . The Dorcatherium −fold is rounded and poorly developed, and the Tragulus −fold is absent. The entoconid is located almost in front of the hypoconid, whereas is displaced in the type species. The lingual cusps are not aligned, at least not at the level of A. moruorotensis . The posterior cingulid is less developed than that of the type species. The anterior cingulid is strong and there are no ectostylids.

Upper molars.—The upper molars of A. parvus are very similar to that of the type species ( Fig. 3D View Fig ). The molars are more selenodont than those of Dorcatherium . The lingual ribs are strong and the mesostyle is well developed. The post−proto−

doi:10.4202/app.2009.0087

crista is short, but the pre−metaconulecrista is well elongated, almost reaching the internal side of the buccal wall. The protoconal cingulum is strong, but it is lost in the metaconule. There is no entostyle.

Astragalus.—The astragali BMNH M82687 and BMNH M82688 are extraordinarily similar to the specimen BMNH M82382 from Moruorot; they are narrow and tall, with a triangular shaped proximo−plantar facet for the calcaneum ( Fig. 3G, H View Fig ).

Stratigraphic and geographic range.—“ Dorcatherium ” parvum has been cited from the late early Miocene of the Napak Member in Uganda ( Pickford 2002). Also a form described as “ Dorcatherium ” sp. cf. “ D.” parvum has been cited in the basal early Miocene of Langental, Namibia ( Quiralte et al. 2008). See Discussion.