Mops cf. M. condylurus, 1842

Gunnell, Gregg F., Butler, Percy M., Greenwood, Marjorie & Simmons, Nancy B., 2015, Bats (Chiroptera) from Olduvai Gorge, Early Pleistocene, Bed I (Tanzania), American Museum Novitates 2015 (3846), pp. 1-35 : 20

Mops cf. M. condylurus

Figure 11

Molossidae indet. (in part), Butler, 1978: 66; Gunnell, 2010: 587.

REFERRED SPECIMEN: NMT.031/Bat, right distal humerus from FLK NI, layer 3, Tr. III.

DESCRIPTION AND COMPARISONS: The humeral specimens described below can all be recognized as molossids based on the presence of a relatively small and rounded humeral head that is positioned well below the trochiter, a bilaterally narrow and angled (proximomedially to distolaterally) capitulum, a bilaterally narrow trochlea separated from the capitulum by a moderate to distinct trochlear groove, an extended and robust capitular tail that is separated from the capitulum by a deep groove, and a well-developed and distally extended epitrochlear process.

The specimen referred here to Mops cf. M. condylurus (as well as those referred to Mops cf. M. thersites below) resembles those of extant species of Mops in having an angled capitulum that is separated from the trochlea by a shallow yet distinct groove and from the lateral capitular tail by a deeper and well-formed groove. The epicondylar process is distinct but does not extend very far beyond the distal edge of the trochlea. Molossus differs from the Olduvai molossids in having: a less distinct groove between the capitulum and trochlea, a shallower groove between the capitulum and capitular tail, and a much more distally extended epitrochlear process (see Simmons and Geisler, 1998: fig. 33). The Olduvai molossids resemble Eumops in possessing a shallow groove between the capitulum and the trochlea but differ in having a narrower (proximodistally) lateral capitular tail that is separated from the capitulum by a shallower groove. The Olduvai molossids also are similar to Tadarida , Otomops , Myopterus , and Chaerephon in sharing a relatively broader and angled capitulum but differ in having a relatively more elongate trochlea (proximodistally). Additionally, the Olduvai molossids have a more robust and more distinctly separated capitular tail than either Myopterus or Otomops do.

Olduvai specimen NMT.031/Bat represents a molossid very similar in size (see table 1 for comparative measurements) and morphology to extant Mops condylurus , which is today known from most of Africa south of the Sahara ( Simmons, 2005). In anterior view, the distal end of NMT.031/Bat shows a narrow, medially angled capitulum that is not offset from the shaft. The lateral capitular tail is not as broad as the trochlea but is nearly as deep and is separated from the capitulum by a relatively deep groove. The trochlear surface is relatively broad and well defined, is separated from the capitulum by a weak groove, and has weakly defined medial trochlear lip. The medial epicondyle is not wide but is robust. The epicondylar process on NMT.031/Bat is broken so it is not possible to determine its extent. Posteriorly, the groove on the lateral surface of the epicondyle is very weak to absent. NMT.013/Bat differs from M. condylurus in having a relatively less deep trochlea and a somewhat wider capitulum, especially at its distal extent.

Figures

FIGURE 11. Right distal humerus of Mops condylurus (NHMUK 20.6.13.1) compared with Mops cf. M. condylurus (NMT.031/Bat) in A, anterior, B, posterior, C, medial, and D, lateral views.