Diomedavus, Ancient Albatross from Oligocene of Washington State

Albatrosses are a group of seabirds related to petrels that are specialized for soaring on long wings, and include the “great albatross” Diomedea, which has the largest wingspan (11+ feet) of any bird living today. (Some extinct types of seabirds (pelagornithids, not closely related to albatrosses) had estimated wingspans up to 24 feet!) A new paper describes fossils found in Washington state that add important details of the evolution of albatrosses. The material was found near Knappton in Pacific County by Burke associate and fossil collector Jim Goedert (one of the authors on the paper) and comes from two formations, the late Oligocene Lincoln Creek Formation and the middle Miocene Astoria Formation.

The Oligocene-age fossils include diagnostic material from wings, legs, and vertebrae, with additional material thought to be from the same species, including a partial pelvis. Because the anatomical details set the bird apart from any known form, the authors made it a new genus and species called Diomedavus knapptonensis. Diomedavus (“Diomedea ancestor”) was related to the modern great albatross but was much smaller and had notable differences in its wing structure.

The Miocene fossils also clearly come from some type of albatross, but don’t currently include parts that allow the ancient seabird to be rigorously compared at a species level with material known from other fossil albatrosses. Although it’s very likely that the fossils do belong to a new species, the authors have decided for now not to give it a formal scientific name and refer to it as the “Astoria Formation albatross.” The Miocene albatross was larger than the earlier Diomedavus and a bit smaller than the living black-browed albatross (Thalassarche melanophris).

Gerald Mayr & James L. Goedert (2017) Oligocene and Miocene albatross fossils from Washington State (USA) and the evolutionary history of North Pacific Diomedeidae. The Auk 134(3): 659–671

http://www.bioone.org/doi/abs/10.1642/AUK-17-32.1

Free pdf:

http://www.bioone.org/doi/pdf/10.1642/AUK-17-32.1

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