الفهرس 
CONTENTSOnly 14 pages are availabe for public view
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Abstract
Over about 10 million years, the ancestors of whales transformed from herbivorous, deer-like, terrestrial mammals into carnivorous and fully aquatic cetaceans. Protocetids are Eocene whales that represent a unique semiaquatic stage in that dramatic evolutionary transformation. Three protocetid genera have been named from Egypt, including Protocetus (the first-named protocetid), Aegyptocetus, and Aegicetus (the latest surviving protocetid ever). Here, we report on a new medium-sized protocetid, Phiomicetus anubis gen. et sp. nov., consisting of a partial skeleton (MUVP 500) from the middle Eocene (ca. 43-42 Ma) of the Fayum Depression in Egypt. MUVP 500 is an associated partial skeleton of a single individual represented by skull, mandibles, two vertebrae, including the fifth cervical and the sixth thoracic vertebrae, and ribs fragments. MUVP 500 is a protocetid whale based on the retention of the upper third molar, identifiable trigonid and talonid in molars and absence of distinct accessory denticles on preserved postcanine teeth. The new species differs from other protocetids in having large, elongated temporal fossae, anteriorly placed pterygoids, elongated parietals, an unfused mandibular symphysis that terminates at the level of P3, 51% of total preserved dentary length, longer than most other protocetids and a relatively enlarged I3. Unique features of the skull and mandible suggest a capacity for more efficient oral mechanical processing than the typical protocetid condition, thereby allowing for a strong raptorial feeding style. Dimensions of the skull and the mandibles and the epiphyses of the vertebrae of MUVP 500 suggest a medium adult protocetid, close in size to Rodhocetus, with an estimated body length of about 3 meters and a body weight of about 600 kg. The retention of a large, plate‐like coronoid process and much larger temporal fossa, suggest a larger cross-section of the temporalis muscle, which in turn suggests a more powerful bite force associated with a strong raptorial feeding style. The scarcity of limbs and postcrania may relate to disarticulation caused by shark scavenging since shark bite marks are preserved on the ribs. Phylogenetic analysis nests Phiomicetus within the paraphyletic Protocetidae, as the most basal protocetid known from Africa. Recovery of Phiomicetus from the same bed that yielded the remingtonocetid Rayanistes afer provides the first clear evidence for the co-occurrence of the basal cetacean families Remingtonocetidae and Protocetidae in Africa. The discovery of Phiomicetus further augments our understanding of the biogeography and feeding ecology of early whales.