الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 419 |  |  |
| | | from | 419 | | |
Abstract
The fossiliferous deposits exposed north of Birket Qarun in the Fayum Depression, Egypt, have produced a remarkable collection of fossil mammals. Palaeontological research in these sediments has led to the discovery of significant material of rodents from two major late Eocene sites; the earliest late Eocene (approximately 37 Ma) Birket Qarun Locality 2 (BQ-2) and the terminal late Eocene (~34 Ma) Locality 41 (L-41). The new fossil material includes cranial and postcranial bones of two rodent groups (Hystricognathi and Anomaluroidea). from BQ-2 sediments, the smallest and largest known Palaeogene anomaluroids, Shazurus minutus and Kabirmys qarunensis, respectively, are described on the basis of isolated teeth and cranial fragments. The considerable differences in body size and molar morphology of Shazurus and Kabirmys suggest that these taxa had an ancient origin on the Afro-Arabia continent; that ancestor might have been derived from a zegdoumyid-like ancestor. Anomaluroid postcranial bones also have been collected from BQ-2, most of which are attributable to Kabirmys; one calcaneus is assigned to Shazurus. The bones bear generalized and primitive features that were likely present in the ancestral crown rodent, including characters that are similar to ground squirrels, and Kabirmys shows no evidence from its forelimb that this primitive species had a patagium or engaged in gliding lifestyle.New genera and species of the oldest well-dated hystricognathous rodents, Protophiomys aegyptensis and Waslamys attiai, are also described from BQ-2. These taxa show a mosaic of primitive and derived features seen in other Palaeogene hystricognathous rodents. Cladistic analysis supports an Asian origin for stem Hystricognathi and an Afro-Arabian origin for crown Hystricognathi, stem Hystricidae, and stem Caviomorpha. The late Eocene rodents from L-41 are only represented by members of Hystricognathi; no anomaluroids have been found at this, or any younger, level. A new family, Gaudeamuridae, is erected, and two new species, Gaudeamus aslius and Gaudeamus hylaeus, are described, based on complete crania and almost complete dentitions. The two new species represent the oldest records of Gaudeamus to date. Furthermore, a new basal stem phiomorph, Acritophiomys bowni, from L-41 is described based on complete dentitions and cranial fragments. This new taxon is the largest phiomorph from Quarry L-41, and exhibits a combination of primitive and derived features, the former shared with the stem phiomorphs from BQ-2 and the latter shared with Oligocene phiomorphs from younger Fayum quarries. In addition, two new genera and species of primitive phiomorph rodents, Birkamys korai and Mubhamys vadumensis, are described. Birkamys is the smallest of known Palaeogene hystricognaths and, like derived Oligocene-to-Recent phiomorphs, apparently retains dP4 very late into life. Mubhamys is very similar in dental morphology to B. korai but has lower molars that are about 3.5 times larger than those of that species.