Morus peninsularis Brodkorb, 1955

Mourer-Chauviré, Cécile & Geraads, Denis, 2010, The Upper Pliocene Avifauna of Ahl al Oughlam, Morocco. Systematics and Biogeography, Records of the Australian Museum 62 (1), pp. 157-184 : 163

Morus peninsularis Brodkorb, 1955

Fig. 4B–D

Material. Right quadrates, AaO-727, 827; left quadrate, AaO-728; vertebrae, AaO-819, 828, 829, 830, 831, 832, 833, 834, 871; right coracoid, sternal part and shaft, AaO-725; left coracoid, almost complete, AaO-2108; right humerus, fragment of distal parts, AaO-730, 2639; left humerus, distal part, AaO-726; right ulna, distal part, AaO-2642; left ulna, proximal part, AaO-2641; right carpometacarpi, AaO-2643, 2644; alar phalanges, AaO-2645, 2646, 2647; left femora, AaO-724, proximal part, AaO-2648; right tibiotarsus, distal part, AaO-729; right tarsometatarsus, distal part, AaO-731, trochlea of digit IV, AaO-732.

The species Morus peninsularis was described by Brodkorb (1955) from the Upper Bone Valley locality, in Florida , which is dated to the lower Pliocene, age about 5 to 4.5 Ma ( Becker, 1987a,b). This species is very abundant in the PlioceneYorktown Formation, North Carolina (Olson & Rasmussen, 2001). The holotype of the species is an almost complete coracoid. Compared to the holotype, the Ahl al Oughlam coracoid AaO-2108 is of similar length but slightly more robust. The length of the dorsal and ventral sternal facets is longer, the acrocoracoid bulges a little more, and the pneumatic foramina are slightly more developed. In Morus bassanus the scapular facet is strongly projecting dorsally, but it is less projecting in M. peninsularis . Also in M. bassanus the clavicular facet is medioventrally oriented while in M. peninsularis it is more ventrally oriented. By these two characteristics the coracoid AaO-2108 is more similar to M. peninsularis .

The dimensions of the specimens referred to Morus peninsularis are similar to the dimensions of those from the Yorktown Formation preserved in the USNM collection and illustrated by Olson & Rasmussen (2001, pl. 12 and 13), except for the distal part of tibiotarsus AaO-729, which is slightly smaller ( Table 3). The carpometacarpus AaO-2643 has a large pneumatic foramen on the ventral face, in the Fossa infratrochlearis, but this is not visible on the specimen AaO-2644 which is incompletely preserved. Both carpometacarpi have another, small, foramen, going right through the Processus alularis, at the level of the junction between the alular and the major metacarpals. The femora also have a pneumatic foramen on the cranial face, distal to the Crista trochanteris. These pneumatic foramina are less developed in Recent species of the genus Morus .

Figures

Figure 4. (A) Phoebastria sp. cf. P. nigripes, left humerus, distal part, AaO-718, cranial view. Morus peninsularis, B–D: (B) left coracoid, AaO-2108, ventral view; (C) right carpometacarpus, AaO-2643, ventral view; (D) left femur, AaO-724, caudal view. Morus sp. cf. M. bassanus, E–F: (E) right humerus, distal part, AaO-4801, cranial view; (F) left ulna, proximal part and shaft, AaO-2640, craniodorsal view.Geronticus olsoni n.sp., G–K: (G) right humerus, distal part and shaft,AaO-838, cranial view; (H) left coracoid,AaO-741, holotype, dorsal view; (I) idem, ventral view; (J) left tibiotarsus, distal part, AaO-2654, cranial view; … [caption continued on facing page]