Talpa minuta Blainville, 1838

Ziegler, Reinhard, 2003, Moles (Talpidae) from the late Middle Miocene of South Germany, Acta Palaeontologica Polonica 48 (4), pp. 617-648 : 631-634

Talpa minuta Blainville, 1838

Fig. 7 .

Material (measurements see Tables 7, 8).—Petersbuch 6: NHMA P6−1058B1, 1059/4, 6, 1060/1, 1062/2, 3, right dentary and right maxilla fragment with teeth, right P4, left humerus, 2 left ulnae; CRW P6−1058–1062, Petersbuch 6, 19 dentary fragments with teeth, 8 maxilla fragments with teeth, 18 humeri, 4 ulnae. Petersbuch 10: CRW P10−0601–607, 622−62, 6 dentary fragments with teeth, 3 maxilla fragments with teeth, 5 isolated teeth, 26 humeri, 13 ulnae. Petersbuch 18: CRW P18−0749–751, 6 dentary fragments with teeth, 3 maxilla fragments with teeth, 5 isolated teeth, 2 humeri. Petersbuch 31: CRW P31−0159–162, 3 dentary fragments with teeth, 2 maxilla fragments with teeth, 33 isolated teeth, 43 humeri, 8 ulnae, 3 radii. Petersbuch 48: CRW P48−0091, 92, 7 isolated teeth, 6 humeri.

Description

Dentary.—In general shape the dentary is similar to that of the extant Talpaeuropaea. The complete ascending ramus is only preserved in the Petersbuch 6 sample. It forms a nearly right angle with the horizontal ramus. The mandibular foramen is situated on the ventral margin of the mylohyoid ridge, roughly in the centre of the ascending ramus. The masseteric fossa is deeply excavated, the pterygoid fossa only moderately deep. The angular process is shovel−shaped with an internal concavity. The cylindrical condylus is situated high above the level of the tooth row. The coronoid process itself is rectangular. In the Petersbuch 6 sample the posterior mental foramen is located either under the anterior root of m1 (twice) or between its roots (four times), the anterior mental foramen below the posterior root of p2 (twice) or between p2 and p2 (twice) or under the anterior root of p3 (once). The incisor alveoli are not preserved.

Lower dentition.—The canine is incisor−shaped and slightly procumbent. All premolars are double−rooted, p2

and p3 overlap one another. p1 is distinctly larger than p2 and p3, but all are similar in shape. The cusp is centred over the anterior root and origin of a marked posterior crest, joining a posterior cuspule, and a less well−developed anterior crest. The buccal face is convex, the lingual side flat. A faint cingulid is restricted to the posterior part of the crown base. The p4 has a talonid and a trilateral crown with convex buccal and lingual faces and a concave posterior side. The postero−lingual crest joins the posterior cuspule. An anterior cuspule is also developed. The size relation between the molars is m1<or>m3<m2. Buccal cingulids are rudimentary and confined to the hypoflexid. The trigonid is lingual open. In the m1 the talonid is wider than the trigonid, the oblique cristid joins the middle of the protocristid or ends slightly labial to the middle. The most conspicuous feature is the faint ascending precingulid, which joins the paracristid. The protoconid of the m2 is the highest cusp in the tooth row. The trigonid is somewhat wider than the talonid. There is a marked precingulid and a tiny cuspule in front of the entoconid. The m3 is similar to a small m2 without entostylid and with a narrower talonid.

Maxilla.—Larger fragments of maxillae are preserved only in the Petersbuch 6 sample. The origin of the zygomatic arch lies above M3. The infraorbital foramen opens high above the middle of M1. The infraorbital canal runs in a deep groove. Its anterior and posterior opening are separated by a narrow bony bridge above the anterior root of M3. The same configuration is found in extant Talpa .

Upper dentition.—According to the alveoles there are three single−rooted incisors. Only two chisel−shaped I2 and I3 are preserved. The double−rooted canine has a mesio−lingual groove and a distal crest. P1–P3 are double−rooted, P2 is smaller than both the others. No P1 is preserved. P2 and P3 have an oval outline in occlusal view. There is a distal crest. A faint disto−buccal cingulum may be developed. The P4 has a more or less projecting parastyle and a conical protocone. A straight distal crest originates from the paracone. The upper molars have an undivided mesostyle and neither paranor metaconule. In the M1 the marked paracingulum joins the projecting parastyle. The metacingulum is interrupted along the postmetacrista or reduced to a short spur above the metastyle. There are four roots, the strongest above the protocone, a mesio−distally compressed one above paracone and postmetacrista respectively, and a small round one on both the labial roots. M2 and M3 have three roots and neither para− nor metacingulum.

Postcranial bones.—Humerus, ulna, and radius are smaller than in the extant Talpa , but do not show any morphological differences. Therefore we can abstain from a formal description. Even in the gracility index, defined as Bp*100/Gl, they correspond to T.europaea . This means that both have similar fossorial abilities. However, the extant Talpa europaea is distinctly larger.

Discussion

With the exception of Petersbuch 35, which yielded only two talpid species, Talpaminuta is represented in all samples and it is the most common talpid in all samples. There are no morphological differences among the specimens under study and Talpa minuta from the type locality Sansan. The position of the anterior mental foramen from this locality is as variable as in the samples under study. In the Sansan sample the posterior mental foramen is consistently situated under the anterior root of m1 whereas it slightly varies in position in the Petersbuch samples. However, there is a distinct difference in size, the dentition and postcranial bones from Sansan being smaller than in Petersbuch. It is assumed that the size difference lies within the variability of a species and that the delineation of a new species or subspecies is not justified. Talpa minuta is one of the most common and most wide spread talpid species in the Miocene of Europe. It is recorded from faunas correlated with MN 3, e.g., Wintershof−West, to MN 9, for example, Nebelbergweg ( Ziegler 1994; Kälin and Engesser 2001), from Slovakia in the East to Southeast France in the West.

Figures

Fig. 7. Talpa minuta, Petersbuch 6. A. Right dentary with p1–m3, NHMA P6−1058B1 in occlusal (A1) and buccal (A2) views; ca. × 5. B. Right maxillary fragment with M1–M3, NHMA P6−1059/6, occlusal view; ca. × 10. C. Right P4, NHMA P6−1059/4, occlusal view; ca. × 10. D. Left humerus, NHMA P6−1060/1, in anterior (D1) and posterior (D2) views; ca. × 5. E. Left ulna, NHMA P6−1062/3, anterior view; ca. × 5. F. Left ulna, NHMA P6−1062/2, lateral view; ca. × 5.