A REVISION OF THE FOSSIL GENUS MIOCEPPHUS AND OTHER MlOCENE ALCIDAE (AVES: CHARADRIIFORMES) OF THE WESTERN NORTH ATLANTIC OCEAN

摘要

This study reviews and describes all known fossils of Alcidae from the Miocene of the western North Atlantic. Because the majority of alcid fossils recovered from Miocene sediments are allied with the genus Miocepphus Wetmore, 1940, the genus is revised here. Three new species of Miocepphus are described: Miocepphus bohaskai and Miocepphus blowi from the Early to Late Miocene, and Miocepphus mergulellus of uncertain Neogene age but probably Miocene. A new genus and species, Pseudocepphus teres, from the Middle and Late Miocene, has uncertain relationships within the Alcinae (a clade comprising Miocepphus, Alle, Uria, Alca and Pinguinus). The genus Alca is also reported from Late Miocene sediments. The newly recognised presence of three genera of the Alcinae in the Miocene of the North Atlantic indicates that the diversity of the subfamily was considerably greater than was evident previously. Miocepphus may be regarded as ancestral to modern Alcinae. The Alcinae as a group was well established in the Early Miocene, indicating that the divergence of the family Alcidae predates 20 Ma. The divergence of Uria and Alca predates 10 Ma.