Eotragus lampangensis Suraprasit & Chaimanee & Chavasseau & Jaeger 2015
Creators: name: Suraprasit, Kantapon
name: Chaimanee, Yaowalak
name: Chavasseau, Olivier
name: Jaeger, Jean-Jacques
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Artiodactyla
Bovidae
Eotragus
Eotragus lampangensis

description: Eotragus cf. lampangensis
Fig. 2B–D, Table 2
.
Material: Mae Moh coal mine, Northern Thailand; late middle Miocene (13.4–13.2 Ma), Nakhaem Formation, coal layer Q—UPP MM-29, right horn core attached to a portion of the dorsal orbital roof; UPP MM- 55, partial right horn core with pedicle; UPP MM- 56, fragmentary right horn core.
Description.—UPP MM- 29 (Fig. 2B) represents a virtually complete horn core missing only a small part of its apex. In lateral view, the horn core is situated slightly posterior to the orbit and is inclined posteriorly at an angle of about 55° degrees relative to the frontal plane. The horn core is short, conical, and entirely oval in cross section (i.e., transversely compressed) along its entire length (Fig. 2B 5, Table 2). The longitudinal axis of the horn core is rather straight, without any torsion. Overall, the surface of the horn core is relatively rough. In lateral view, the anterior surface is moderately concave, whereas posterior one is slightly convex (Fig. 2B 2, B 3). The lateral surface of the horn core is slightly flatter than the medial one. There is no anterior keel, whereas the posterior keel, originating about 1 cm above the base of the posterior surface and terminating at the apex, is faint. The anterior portion of the pedicle is slightly higher than the posterior one, and its surface is relatively smooth.
UPP MM- 55 (Fig. 2C) preserves only the lower part of the horn core with the pedicle and some parts of the orbital roof. The cross section of the horn core is suboval at the base (Fig. 2C 5). Both the anterior and posterior surfaces of the preserved basal horn core are relatively flattened and bear no obvious keels. The lateral surface is flatter than the medial one. The surface of the horn core is rough.
The fragmentary horn core represented by UPP MM- 56 (Fig. 2D) is also suboval in cross section (Fig. 2D 5), with its base being more massive anteriorly than posteriorly. There is no keel on its flattened anterior surface, but a moderately distinct keel is present on its posterior side. The lateral surface of the horn core is more flattened than the medial one. The surface of the horn core is rough.
Remarks.—Both UPP MM- 55 and UPP MM- 56 are slightly larger than UPP MM- 29, probably as a result of size variation within the population. These three horn cores differ from those assigned to Eotragus lampangensis sp. nov. in being shorter relative to their basal diameter and oval in cross section, as well as in their more conical shape, straight longitudinal axis, and less concave anterior surface. They further differ in the position of the posterior keel on the posterior surface, the absence of a distinct anterior keel, and their comparatively small size. However, it should be noted that the size difference between these specimens and E. lampangensis sp. nov. falls within the range of intraspecific variation shown by E. clavatus (Fig. 5), while the morphological differences resemble those between E. clavatus from Sansan, France, and E. aff. clavatus from Tarazona de Aragón, Spain (Table 4). Rather than erecting a new species, we therefore decided to assign the material described here to E. cf. lampangensis.
description: Published as part of Suraprasit, Kantapon, Chaimanee, Yaowalak, Chavasseau, Olivier & Jaeger, Jean-Jacques, 2015, Middle Miocene bovids from Mae Moh Basin, Northern Thailand: The first record of the genus Eotragus from Southeast Asia, pp. 67-78 in Acta Palaeontologica Polonica 60 (1) on page 73, DOI: 10.4202/app.2012.0061, http://zenodo.org/record/10626329