Desmanella cf. stehlini Engesser, 1972

Ziegler, Reinhard, 2003, Moles (Talpidae) from the late Middle Miocene of South Germany, Acta Palaeontologica Polonica 48 (4), pp. 617-648 : 640-643

Desmanella cf. stehlini Engesser, 1972

Fig. 11 .

Material and measurements.—Petersbuch 6: NHMA P6−1064, left dentary fragment with m1–m3, Lm1–m3 (4.19), m1 (1.53×1.00×1.03), m2 (1.59×1.04×1.02), m3 (1.26×0.80×0.62). Petersbuch 18: NHMA P18−754, left dentary fragment with p4–m3, Lm1–m3 (4.15), m1 (1.57× 0.93×1.07), m2 (1.61×0.99×1.00), m3 (1.26×0.76×0.65). Petersbuch 31: NHMA P31−0165/1, left dentary fragment with p3+m2, p3 (0.49×0.45), m2 (>1.5×0.97×0.96); CRW P31−0165/2, right dentary fragment with p3–p4, p3 (0.42× 0.40), p4 (0.97×0.69); NHMA P31−0165/3, right dentary fragment with p4–m1, p4 (0.92×0.67), m1 (1.46×0.95×1.08); NHMA P31−0165/4, left dentary fragment with m1, m1 (1.48×1.01×1.10).

Description

Dentary.—Only short fragments of the horizontal ramus are preserved. The specimen from Petersbuch 18 shows the posterior mental foramen between the roots of p4 and m1 and the anterior one under the third root anterior to p4, the p1 alveolus. In the small sample from Petersbuch 31 the anterior mental foramen is below p2 (twice) or between the roots of p1 and p2 (once) and the posterior one beneath the trigonid of m1. One specimen shows the complete set of antemolar alveoles. There is one alveolus each for i2, i3, c, p1, p2, and p3. Consequently, the lower tooth formula is 2−1−4−3.

Lower dentition.—The teeth anterior to p3 are not preserved. Their alveoli show that all are single−rooted. The likewise single−rooted p3 has a conical cusp with a posterior cingulid. The double−rooted p4 is oval in occlusal outline. The crown has a concave posterior face, a convex mesiobuccal side, and a flat mesio−lingual one. The posterior cingulid encompasses a short talonid.

The molars are slightly inflated and low−crowned. The size relation is m2>m1>m3. In m1 the oblique cristid joins the centre of the protocristid, in m2 and m3 it extends more lingually but does not join the weak metacristid. There is no well−developed metacristid in m1, but a weak, descending entocristid. A moderately developed cingulid runs from below the paraconid to the hypoflexid. The weak postcingulid joins the entostylid. The m2 and m3 are characterised by their short talonid. In m2 the protoconid is somewhat higher, the talonid narrower, and the oblique cristid joins the marked metacristid. The m3 has neither postcingulid nor entostylid.

Discussion

Desmanellastehlini, the genotype, was described for the first time by Engesser (1972) on the basis of six isolated molars from the Anwil fauna. The specimens under study fit well in morphology and length with the molars from the type locality, but they are narrower. The dentaries and teeth from Petersbuch 6+18 correspond well in size with those from Petersbuch 31, but differ in the slightly more posterior position of the mental foramen and in the somewhat weaker preand ectocingulid of m2. The position of the mental foramen is not known from D.stehlini from the type locality. For want of the upper dentition in our material the presence of important characters cannot be verified. Hence the determination is Desmanella cf. stehlini .

To date, the record of D. stehlini is extremely sparse. Kälin (1993) reported on five isolated teeth of D. aff. stehlini from Le Locle sous le Stand, Switzerland, which is correlatable with MN 7+8. Kälin and Engesser (2001) designated two isolated teeth from Nebelbergweg, a MN 9−fauna from Switzerland, Desmanella sp. Probably they also represent D. stehlini . The authors refrained from specific determination because of insufficient material. Crochet and Green (1982) referred 15 isolated teeth and a dentary fragment from Montredon, an Upper Miocene (MN 10) fauna from France, to Desmanella cf. stehlini . The genus Desmanella itself has a long stratigraphic range. The earliest records are from the Oligocene/Miocene transition in South Germany ( Ziegler 1990), the latest is represented by Desmanella gardiolensis Crochet, 1986 from the Late Pliocene (MN 16) fauna Balaruc 2 in South France ( Crochet 1986).

The subfamilial allocation of the genus is a matter of continuous dispute. Desmanella was referred to the Desmaninae ( Engesser 1972) , the Talpinae ( Storch 1978) and by most students to the Uropsilinae (e.g., Rümke 1974, 1976; Engesser 1980; Ziegler 1985; Crochet 1986; and van den Hoek Ostende 2001). The whole story is reviewed and comprehensively discussed in Dahlmann (2001) and van den Hoek Ostende (2001). My arguments for an allocation with the Uropsilinae have been the associated humeri of D.engesseri , which are characterised by the absence of a bicipital tunnel. According to Campbell (1939), except from the Uropsilinae in all mole humeri the walls of the bicipital groove are fused to form a tunnel. However, in the Recent Urotrichus talpoides the bicipital groove is not fully ossified but rather closed by cartilage ( Dahlmann 2001: 47). Another particularly important character of the uropsiline humerus is the rounded caput, which is elliptical in all other talpids. The humerus of D. engesseri has an elliptical caput (see Ziegler 1985: fig. 2b, 1994: pl. 1: 6, 7), hence they cannot belong to an uropsiline. I think, with respect to humerus morphology, Desmanella is better placed within the Urotrichini . Dental morphology and tooth formula is compatible with this allocation. The presence of a functional milk dentition, the main argument of the Uropsilinae advocates, is also known from some Urotrichini , for example Urotrichus Temminck, 1841 and Quyania chowi Storch and Qiu, 1983 .

Urotrichini gen. et sp. indet. I

Fig. 12 .

Material and measurements.—Petersbuch 10: NHMA P10−616/1, left dentary fragment with p3, p3 (0.93×0.53); NHMA P10−616/2, right m1 (1.78×0.87×1.01); NHMA P10−617, right humerus GL (10.3), Bp (6.17), BpwT (4.55), DS (2.03), Bp*100/GL (59.9).

Description

Dentary.—There is one dentary fragment with the alveoli of i1–m1, a double−rooted p3, and the talonid of p4. In this specimen a small posterior mental foramen is situated under the anterior root of p4, the anterior one beneath p2. There are five alveoli anterior to p3 for the single−rooted i1, i2, i3, p1, and p2. The incisors are increasingly inclined, i1 being the largest. The canine is assumed to be eliminated. In the p3 the crown is buccally convex and flat on the lingual side. It is surrounded by a cingulid which tapers lingually. From the p4 only the posteriormost part with the marked postcingulid is preserved.

m1.—There is one isolated specimen with a notched paraand protocristid respectively. The oblique cristid extends far lingually but does not join the metacristid. The precingulid is short; the ectocingulid restricted to the hypoflexid, the postcingulid is extremely weak and short.

Humerus.—The supratrochlear fossa, the fossa for the m. flexor digitorum profundus ligament with the medial epicondyle and the greater tubercle with the deltoid process are broken away. In spite of the fracture the deep notch between trochlea and the fossa, which characterises the urotrichines, is partly preserved. The pectoral tubercle extends halfway down the shaft and is situated in its mid, not laterally as in the other urotrichines. The brachialis fossa is only partly preserved; it was only moderately deep. Greater tubercle and head are separated by a deep groove. There is a notch between and lesser tubercle and teres tubercle.

Discussion

The humerus is the largest and most robust among the urotrichine humeri of all samples under study. It is associated with the biggest urotrichine dentary and the biggest urotrichine m1 of the Petersbuch 10 talpid sample. There is no more probable alternative to this association, nonetheless it is considered tentative. Neither humerus nor dental remains fit well with any known species or genus. In view of the uncertainties concerning the association and as the material is too scarce the description of a new taxon is not possible.

Urotrichini gen. et sp. indet. II

Fig. 13 .

Material and measurements.—Petersbuch 31, P31−171/1–6: NHMA P31−171/1,leftm2 (1.61×0.99×0.93); CRW P31−171/2, right m2 (1.77×1.05×1.08); NHMA P31−171/3, right M1 (2.06×1.47); NHMA P31−171/4, left M2 (1.90×1.87); CRW P31−171/5, right M2 (1.94×1.97); CRW P31−171/6, right M2 (1.57×1.85).

Description

Lower dentition.—In both m2 the metacristid does reach the cusp of the metaconid. It instead ends in a small metastylid below the metaconid. The oblique cristid joins the metacristid. There is a marked precingulid, a short ectocingulid beneath the hypoflexid and a vestigial postcingulid close to the entostylid.

Upper dentition.—The mesostyle of the M1 is nearly confluent in the moderately worn tooth. A slight notch shows that the mesostyle was divided in the unworn tooth. Paraconule and metaconule are differentiated. The preparaconuluscrista is confluent with the strong paracingulum, which itself joins the projecting parastyle. Postmetaconuluscrista and metacingulum are also confluent and terminate in the metastyle. In all three M2 the mesostyle is deeply divided. Paraconule and metaconule a more marked than in the M1. The preparaconuluscrista terminates at the mesial basis of the paracone, the postmetaconuluscrista at the distal basis of the metacone.

Discussion

The teeth cannot be referred to any other species of the Petersbuch 31 talpid fauna. They differ from Tenuibrachiatum storchi in the bigger size, the better developed precingulids of m2 and in the divided mesostyles of the M1 and M2. The marked lingual conules in the upper molars, especially in M2, is a distinct desmanine and urotrichine character. As desman teeth are more massive and differ in a suite of other characters, an affiliation with this subfamily can be excluded. It is assumed that all teeth form a homogeneous sample, in spite of the small M2 (no. 6). The teeth are too small for an association with the dentary of Scalopini gen. et sp. indet. Furthermore, the marked lingual conules of the upper molars better fit with the urotrichines. We cannot exclude that the teeth represent the same species as the indeterminable urotrichine from Petersbuch 10. As both samples have neither teeth nor postcranial elements in common this assumption cannot be corroborated. Hence, the determination is Urotrichini gen. et sp. indet. II.

Talpidae incertae sedis

Figures

Fig. 11. Desmanella cf. stehlini. A. Left dentary fragment with m1–m3, NHMA P6−1064, Petersbuch 6, occlusal view; ca. × 10. B. Left dentary fragment with p4–m3, NHMA P18−754, Petersbuch 18, buccal view; ca. × 10. C. Left dentary fragment with p3 and m2, NHMA P31−165/1, Petersbuch 31, occlusal view; ca. × 10. D. Right dentary fragment with p4–m1, NHMA P31−165/3, Petersbuch 31, buccal view; ca. × 10. E. Left m1, NHMA P31−165/4, Petersbuch 31, occlusal view; ca. × 15.

Fig. 12. Urotrichini gen. et sp. indet. I, Petersbuch 10. A. Left dentary fragment with p3, NHMA P10−616/1, buccal view; ca. × 10. B. Right m1, NHMA P10−616/2, occlusal view; ca. × 15. C. Right humerus, NHMA P10−617, in posterior (C1) and anterior (C2) views; ca. × 7.5.

Fig. 13. Urotrichini gen. et sp. indet. II, Petersbuch 31. A. Left m2, NHMA P31−171/1, occlusal view; ca. × 15. B. Right M1, NHMA P31−171/3, occlusal view; ca. × 15. C. Left M2, NHMA P31−171/4, occlusal view; ca. × 15.