TAKE TO THE SKIES: A NEW TYPE SPECIES PUSHES BACK THE ORIGINATION OF CROWN GROUP ALBATROSSES (AVES, DIOMEDEIDAE)

There is contention over the phylogenetic relationships among modern albatrosses. Neontologists continue to argue over how many distinct species there are among the four modern genera. Similar disagreements are found in the research and descriptions of fossil albatrosses. Fragmentary nature of described extinct albatrosses has obscured the crown group's origination. Insofar, neontologists agree that the modern genera originated during the Pliocene with specific and unique morphologies which distinguish them from earlier albatrosses.

Key morphological characteristics that distinguish crown group albatrosses from those on the stem are found on the cranium and first three cervical vertebrae. These previously proposed traits of the skull are: lateral facing, well-defined nares; a bulge at the proximal base of the beak; a deep furrow along the length of the beak; and a concave culmen. The proposed characteristics of the cervical vertebrae that define the crown group are: a dorsally opened incisura fossae of the atlas and a relatively developed processus costalis of the axis. Additionally, when compared to other crown group albatrosses, the presence of a fairly developed fovea cranioventralis of the third cervical vertebra differentiates the phoebastrids from the other genera.

Until this study, crown group albatross characteristics have only been found in specimens from the Pliocene into the Recent. Here, we describe a newly identified albatross skull and associated cervical vertebrae (UOMNCH F-47133) found in the Miocene deposits of the Astoria Formation in Oregon, USA that may shift the origination of crown group albatrosses. This specimen expresses many of the proposed key morphologies of the cranium and cervical vertebrae that are shared among crown group albatrosses. A unique combination of these traits also supports its identity as a new species. CT analyses will be used to confirm these observed morphological features and may also illuminate other crown group features in the skull and cervical vertebrae obscured by articulation and matrix. The proposed phylogenetic position of the new species suggests the origination of crown group albatrosses is approximately 5 – 10 million years earlier than previously thought; shifting from the Pliocene to the Miocene. Identifying this new species thus affects our understanding of this dynamic clade's evolutionary history.