Apternodus dasophylakas, ASHER & McKENNA & EMRY & TABRUM & KRON, 2002

ASHER, ROBERT J., McKENNA, MALCOLM C., EMRY, ROBERT J., TABRUM, ALAN R. & KRON, DONALD G., 2002, Morphology And Relationships Of Apternodus And Other Extinct, Zalambdodont, Placental Mammals, Bulletin of the American Museum of Natural History 2002 (273), pp. 1-117 : 54-58

Apternodus dasophylakas , new species

TYPE AND ONLY SPECIMEN: UW 14072, crushed but otherwise complete skull (fig. 35) preserving left I1, C­M3, right I1, broken C, P2, broken P3, P4­M3, articulated left dentary with complete dentition, associated right dentary with i1­i2, c­m3 (fig. 36), associated tibia, atlas, axis, partial scapula, proximal humerus, distal ulna, ribs, and other fragmentary postcranial fragments (fig. 37). All elements are slightly distorted due to postmortem deformation.

ETYMOLOGY: This species is named in hon­ or of the faculty, students, and staff of the Department of Geology and Geophysics, University of Wyoming, under whose auspices the type and only specimen was collected and is now curated. The Greek word transliterated as ‘‘ dasophylakas ’’ is an interpretation of the English word ‘‘cowboy’’, the UW mascot. Literally, the trivial name means ‘‘ranger’’ or ‘‘guardian of wild land and forest’’ (N. Soulunias and I. Trivilas, personal commun.).

TEMPORAL AND GEOGRAPHIC DISTRIBUTION: Chadronian (late Eocene) of southeastern Wyoming (Harshman Quarry 21).

DIAGNOSIS: Protocones on the upper molars are absent, a condition somewhat exacerbated by wear. The anterior dentition is premolariform, not bulbous. P3 has an elongate stylar margin, and diastemata are evident on either side of the upper canine, between I1 and I2, and probably also between P2 and P3; some distortion in the maxilla between P2­P3 on both sides precludes certainty as to the size of the P2­P3 diastema. Both P2 and p2 are smaller than adjacent teeth and are similar in proportion to those of A. brevirostris . The mental foramen on the dentary is located just below p2, a position slightly anterior to that of other Apternodus species. The p3 shows a slight buccal cingulid and a distinct posterior cusp. The ex­ ternal auditory meatus of UW 14072 is not marked by a torus, in contrast to that of A. major , but is flat as in A. iliffensis . Another similarity to A. iliffensis is the ventral margin of the lambdoid plate, which reaches just slightly ventral to the level of the jaw joint. The rostral tympanic process of the petrosal is flat. A piriform fenestra is evident, lateral to a small anterior carotid foramen.

REMARKS: UW 14072 is a large version of A. iliffensis , sharing with it aspects of the ear and lambdoid region as well as reduced upper molar protocones and an elongate P3 (polymorphic in A. iliffensis ). UW 14072 differs qualitatively from individuals of A. iliffensis in having an M3 similar in buccolingual width to the M2, an elongate rostrum with diastemata on either side of the canine, and a transversely wide basicranium. It differs from other Apternodus species in having a mental foramen ventral to p2; the position of the mental foramen(ina) is unknown in A. iliffensis . Cranial proportions are similar to those of A. gregoryi , with the exception that A. dasophylakas has a very shallow external auditory meatus and a lambdoid plate that does not extend far ventral to the jaw joint. The orbitotemporal region of UW 14072 is crushed, leaving a very distorted lacrimal foramen on the left side, and none on the right. It is therefore difficult to tell if the posterior border of the lacrimal foramen is flush with the anterior orbit as in Apternodus gregoryi (figs. 21, 22) and A. major (fig. 32). The left craniomandibular joint, with the jaw still in articulation, preserves what might be part of an ossified articular disk separating the condyle from the glenoid fossa (fig. 35). However, due to the postmortem distortion of the specimen, it is difficult to discount the possibility that this region contains multiple fragments of the mandibular condyle itself.

Postcranially, what little is known of A. dasophylakas (fig. 37) does not appear to be specialized for a nonterrestrial locomotor repertoire. The only exception to this observation in any Apternodus specimen may be the structure of the proximal femur in A. gregoryi (UW 13508; see above). The distal tibia of A. dasophylakas is not fused with the fibula. The scapula has a triangular shape, narrow laterally at the glenoid fossa and broadening dorsomedially toward the vertebral column. The second cervical vertebra shows a ventrally projecting keel on the posteroventral aspect of its centrum (similar to the axis of shrews and Echinosorex ); and the first cervical vertebra shows two widely separated facets for the occipital condyles of the skull.

FAMILY OLIGORYCTIDAE , NEW FAMILY

INCLUDED GENERA: Oligoryctes Hough, 1956

DISTRIBUTION AND DIAGNOSIS: As for Oligoryctes .