Angelone et al.—A new endemic leporid from the early Pleistocene of Sardinia


511


Figure 4. Mandibles of Sardolagus obscurus n. gen. n. sp. (1) Left hemimandible with i1, p3-m3 (DSG/URT-053/505) in buccal view; (2, 3) right mandibular ramus (DSG/URT-053/479) in lateral and medial views, respectively; (4, 5) left hemimandible with p3-m2 (DSG/URT-053/476) in buccal and ventral views, respectively.


Description.—We based the taxonomic analyses on isolated teeth, a few mandibular/maxillary fragments, and one incom- plete cranium. Dental measurements are given in Table 1, mandibular and cranial measurements in Table 2. Cranium (Fig. 2.1–2.5).—An incomplete cranium lacking


its right lateral portion (jugale [zygomatic arch], squamosal, alisphenoid), rostrum (premaxillae, nasals, right maxilla), palatine bones, pterygoid, and basisphenoid. Parietals and frontals largely preserved, the latter lacking contact with nasals; skull roof convex; dorsal sutures well preserved, not ossified—sagittal and frontopar- ietal ones corrugated, the latter of “type 4” (sensu Palacios, 1989); unfused interparietal present but not well preserved; occipital condyle small; auditory bullae relatively large. I1 (Fig. 3.20).—Anteroposteriorly flattened, roughly rec-


tangular shape, anterior enamel of moderate thickness with no substantial variation; anterior notch shallow, V-shaped with widely opened walls, not filled with cement, dividing the tooth in two parts of approximately equal anterior prominence, the internal one (~43% of W) anteriorly flattened and rather symmetrical with respect to its anteroposterior axis, in contrast to the curved and asymmetrical external one. P2 (Figs. 2.9 [in part], 3.14–3.19).—Simple hypercone,


relatively narrow and anteriorly tapered, without or with incipient hypoflexus, LL-morphotype I (sensu Fladerer and Reiner, 1996) dominant (I: 57%, II: 29%, III: 14%, IV, V, and VI: 0%; N=7). Lagicone with shallow mesoflexus, BMR- morphotype A (sensu Fladerer and Reiner, 1996) dominant (A: 86%, B: 14%; BMR-morphotype 0: not observed; N=7). Simple paraflexus with variable length (very short in 2 cases). Enamel quite thick on anterior and lingual parts. Upper molariforms (Figs. 2.9 [in part], 3.26–3.30).— Narrow teeth (lowWvalues); relative length of mesial and distal


hyperlophs variable; quite short hypoflexus (71% of W; N=35), usually very slightly undulated or smooth. Abundant cement at the lingual end of the hypoflexus. Thick enamel on the anterior part of the mesial hyperloph and the lingual tips of hypercones; the thickness of enamel in the anterior part of the hypoflexus is variable. Differences in enamel thickness do not depend on tooth positions. Mandible (Figs. 2.6, 2.7, 4).—Mandibular body and ramus


robust; diastema relatively short, of almost the same length of the alveolar row of p3-m3; in buccal view, the alveolar row of p3-m3 appears straight along most of the length; dorsal surface of the mandibular body convex with a distinctive swelling below p3-p4; root end of lower incisor reaching the posterior part of p3; large, anterobucally directed mental foramen placed in the buccal side beneath the p3; area below mental foramen and p3 richly fenestrated; masseteric fossa large compared to the size of the jaw. i1 (Fig. 3.21, 3.22).—Quadrangular, markedly shortened


anteroposteriorly; enamel uniformely thick on the anterior part. p3 (Figs. 2.8 [in part], 3.1–3.5, 3.6 [in part], 3.7–3.13).—


Elongated tooth; adult specimens show A1/PR3 pattern stable along the entire tooth crown; one juvenile tooth shows A1/PR4 pattern in the occlusal surface evolving in A1/PR3 in radical side (cf. Averianov and Tesakov, 1997, p. 152). Depth of anteroflexid variable from 6% to 21% of L (average=14%; N=14). The anteroconid length ranges from 24% to 31% of L (average=28%; N=14); the labial anteroconid tends to be anteriorly more prominent, symmetrical and slightly larger than the lingual one. Protoflexid simple and quite wide, roughly right-angled in most cases; its depth varies from 12% to 21% of W(average= 15%; N=14). A shallow paraflexid or concavity is present in 86% of specimens, and in two cases the notch is


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