Scontromeryx magnus ( Mazza et Rustioni, 2011 )

Van Der Geer, Alexandra A. E., 2014, Systematic revision of the family Hoplitomerycidae Leinders, 1984 (Artiodactyla: Cervoidea), with the description of a new genus and four new species, Zootaxa 3847 (1), pp. 1-32 : 20

Scontromeryx magnus ( Mazza et Rustioni, 2011)

cf. Amphimoschus Gray, 1852 — Mazza & Rustioni 1996: p. 96, fig. 6 [SCT20].

large-sized artiodactyl (present-day fallow deer sized)— Mazza & Rustioni 1996: p. 94, fig. 1 [SCT18]. Hoplitomeryx magnus Mazza & Rustioni, 2011 — Mazza & Rustioni 2011 (partim): p. 1304, 1324, 1325, 1328, 1330, figs 4, 5, tables 1, 2 [SCT18, SCT20, SCT86].

Holotype. Left hemimandible SCT20 ( Figure 4 , J, K, L, in Mazza & Rustioni 2011).

Paratypes. Maxillaries SCT18 (juvenile), SCT86.

Original diagnosis. See Mazza & Rustioni (2011).

Revised diagnosis. Large species with brachyodont cheek teeth. M1 with very reduced entostyle; paracone supported by robust and prominent median rib; external rib of metacone absent; well-developed and lingually protruding parastyle and mesostyle; metastyle very weak; cementum absent and smooth enamel in upper cheek teeth. Mandible with horizontal ramus massive lateromedially, ventral profile moderately convex under cheek teeth corpus. Lower molars with widely spaced, triangular, backwardverging labial cuspids and with flattened mesial enamel walls; protoconid and hypoconid isolated in unworn molars; in worn molars protoconid connected mesially with metaconid and distally with entoconid, and hypoconid connected with postprotocristid and postentocristid; lower molars with lingual cuspids relatively less worn than labial cuspids; metastylid and postentocristid prominent, but blunt; ectostylids blunt and robust; third lower molars with tear-shaped hypoconulid and entoconulid not fused distally; labial enamel wall rugose, lingual wall smooth in lower cheek teeth; protoconids with faint traces of cingulum at their base.

Differential diagnosis. Larger than all other Scontromeryx species. Differs from S. minutus , S. falcidens , S. apulicus and S. apruthiensis by pachyostosis of the mandible. Differs from S. mazzai , S. apulicus and S. apruthiensis by the presence of robust ectostylids in lower molars. Differs from S. falcidens and S. apulicus by rugose labial enamel in lower molars. Differs from S. mazzai and S. apruthiensis by smooth lingual enamel in lower molars.

Derivation of name. Refers to the particularly large dimensions of the individuals of the species.

Preservation and deposition. Soprintendenza Archeologica dell’Abruzzo (Chieti, central Italy).

Type locality and horizon. Tortonian Scontrone Member of the Lithothamnium Limestone ( Patacca et al. 2008; 41°45'15.54''N, 14°02'13.14''E), outskirts of Scontrone, southern border of the National Park of Abruzzi, L’Aquila, central Italy.

Description. See Mazza & Rustioni (2011). Additional characters shown by paratypes revised after Mazza & Rustioni (2001). This is the largest of the species represented in the sample from Scontrone. SCT18 is a very fragmental maxillary of a young specimen with DP 4 in substitution, P3 and P4 (both erupting), M1 and M2. SCT86 is a left fragmentary maxillary with P4-M1. DP4 is molariform, with very robust paracone labial rib; no metacone rib; well-developed parastyle and metastyle; very strong mesostyle. Protocone larger than metacone. Postprotocrista bent forward. As wear progresses, postparacrista and postprotocrista fuse to premetaconule crista. Small entostyle. P3. Strong styles and external rib of paracone. Protocone fairly small, centrally situated, lingually directed and fused to robust metaconule. Metacone relatively small. Two strong spurs issue from lateral enamel walls of lingual cusp, one from preprotocrista, the other from postmetaconule crista. Lingual enamel wall rougher than labial one. No entostyles. M1–M2. Robust parastyle and even stronger mesostyle. Strong external rib of paracone, metacone with no labial rib. Postprotocrista and postmetaconule crista fairly robust, and lingual crescents closely spaced. Lingual enamel wall more rugose than labial one. No entostyle.

Measurements. See Table 2 .

Figures

FIGURE 4. Postcranial elements of Hoplitomeryx. A, right distal humerus (RGM 178.487; Chiro 20 E) showing conical aspect of the trochlea: anterior view; B, distal left humerus (RGM 425.409; Fina N) without a supracondylar foramen: posterior view; C, distal right humerus (RGM 178.483; Chiro 20 A) with a small foramen: posterior view; D, right radius-ulna (RGM 260.916; San Giovannino) with high degree of synostotic fusion: lateral view; E, right radius-ulna (RGM 425.282; San Giovannino) with no fusion: medial view. Variations observed in the distal (left) radius: F, typical cervid pattern with the radial facet extending further than the intermedial facet; both facets are elongated (after Heintz 1970); G, both facets are tear-shaped and equally developed (after Zeder & Lapham 2010); H, the intermedial facet is much smaller than the radial facet and is almost round (after Heintz 1970). I, left metacarpal (RGM 425.350; Gervasio): anterior (dorsal) view; J, right metacarpal (RGM 425.351; Gervasio): posterior (palmar) view; K, right metacarpal (RGM 425.300; San Giovannino): anterior (dorsal) view; L, right metacarpal (RGM 425.300; San Giovannino): posterior (palmar) view. Schematic drawings of metacarpals showing the variation in morphology of the proximal articulation in proximal view: M, pattern seen in RGM 260.919 (San Giovannino), the typically cervid pattern; N, pattern seen in RGM 425.322 (San Giovannino); O, pattern seen in RGM 262.000 (Gargano, unknown fissure); P, pattern seen in RGM 425.350 (Gervasio).