Rhinolophus, Lacepede, 1799

Popov, Vasil V., 2004, Pliocene small mammals (Mammalia, Lipotyphla, Chiroptera, Lagomorpha, Rodentia) from Muselievo (North Bulgaria), Geodiversitas 26 (3), pp. 403-491 : 419-422

Rhinolophus ex gr. euryale Blasius, 1853 ( Figs 9 ; 10 )

MATERIAL EXAMINED. — 2 fragments of mandible with p3-m1 and m1-m2 (Ms166, 167), 4 c1 (Ms168,

169), 1 M1 (Ms170), 2 M2 (Ms171), 4 M3 (Ms172),

20 C1 (Ms173).

MEASUREMENTS. — See Table 3.

DESCRIPTION AND COMPARISONS

C1: the crown outline in occlusal view is elongated and oval, tapering anteriorly. The modern Rh. mehelyi differs from the fossil form in having an extensively developed linguo-distal part of this tooth. In recent Rh. euryale the occlusal outline is more oval, not tapering anteriorly, possessing a postero-lingual depression, lacking in the fossil material.

M1-M2: the posterior emargination and talons are poorly developed, so the molars are, to some extent, similar to those in Rh. euryale (poor emargination, but more developed talon) and Rh. mehelyi (weak talon but more pronounced emargination). The molars of the modern Rh. blasii are quite different in having a well developed talon and respectively much wider crowns (see above).

M3: the crown outline is triangular, similar to Rh. euryale but with more developed posterior (metacone-metastyle) loop.

c1: in occlusal outline, it is an oval or shortened trapezium with rounded corners. The tooth possesses a well developed talon in its posterior part. It is similar to the recent Rh. euryale but differs in having larger size and a rounded anterolingual part.

p3 is relatively large, almost round and lies in the tooth row, situated in such a way that the alveolus of p2 is shifted anteriorly and the crowns of p2 and p4 were probably not contiguous. In this respect, it is similar to some specimens of recent Rh. blasii and Rh. euryale from Bulgaria. However, in general, the three modern species seem more specialized than the fossil form in having more tightly spaced p2 and p4.

p 4 in crown outline resembles an elongated trapezium with its base facing lingually. Its cingulum is well developed, forming a large shelf anteriorly. The tooth is more elongated than in the recent Rh. euryale but close to Rh. blasii . The shape of p 4 in the modern Rh. mehelyi is nearly triangular and thus it is quite different from the fossil material and the other two medium-sized modern species.

m1-m2 are nyctalodontic and elongated, close in their form to the present-day Rh. euryale . The molars are less massive and narrower in comparison with those in recent Rh. mehelyi .

m3: this nyctalodontic tooth possesses a massive talonid similar to the less specialized modern Rh. blasii . In contrast, the talonids of the other two medium-sized species are more delicate.

REMARKS

The above descriptions and comparisons show that the fossil material is nearer to Rhinolophus euryale than to the other two medium-sized species. At the same time it differs from the contemporary species in some important features: a relatively large p3, situated near to the longitudinal axis of the tooth row; more elongated p4; better developed talonid on m3; more massive lower canine with weaker (rounded) anterolingual corner; the occlusal outline of the crown of the upper canine is tapered in its posterior part and does not show any postero-lingual emargination. In some of these characters, the level of specialization is about that of the less specialized (in some respects) recent species of this group, Rh. blasii . Most probably, these similarities correspond to the low evolutionary level of the fossil form and do not indicate that they belong to the same evolutionary lineage. The differences with the modern Rh. mehelyi are greater because it is more specialized, according to the criteria mentioned above.

As compared with the fossil forms, the measurements of the material from Muselievo are close to Rh. neglectus Heller, 1936 and Rh. euryale praeglacialis Kormos, 1934 . Unfortunately, the original descriptions of these species are incomplete and do not permit detailed comparisons. In general, these two forms are slightly larger than the recent Rh. euryale . More detailed information is available for Rh. neglectus from Mala C a v e a n d R e b i e l i c e K r o l e w s k i e 2, P o l a n d ( Woloszyn 1988). The determination of this material is based on a direct comparison with the holotype. The comparison with the data presented by Woloszyn (1988) reveals some differences such as shorter teeth (p4, m1, m2, M2) and less massive upper canines in the Muselievo material. At the same time, the only available mandible from Muselievo is similar with Rh. neglectus in the premolar arrangement. Most probably, this similarity is a shared plesiomorphic feature of the Pliocene forms and is not necessarily an indication for their close relationship. According to Woloszyn (1988), M. neglectus should be considered as a form closely related with Rh. mehelyi . On the other hand, the above considerations show that the fossil sample under study is more similar to Rh. euryale . The only assumption one can draw so far is that the material from Muselievo belongs to a primitive form within the phyletic lineage leading to the contemporary Rhinolophus euryale .

Figures

FIG. 9. — Rhinolophus ex gr. euryale Blasius, 1853; A, right upper canine, Ms173, occlusal view; B, the same, buccal view; C, the same, lingual view; D, fragment of right mandible with m2-m3, Ms167, occlusal view; E, the same, labial view; F, the same, lingual view; G, left lower canine, Ms168, occlusal view; H, the same, buccal view; I, the same, lingual view. Scale bar: 1 mm.

FIG. 10. — Rhinolophus ex gr. euryale Blasius, 1853; A, right M1, Ms170, occlusal view; B, right M2, Ms171, occlusal view; C, right M3, Ms172, occlusal view; D, right fragment of mandible with p4-m1, Ms166, occlusal view; E, the same, labial view; F, the same, lingual view. Scale bar: 1 mm.