Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Into Thinner Air: The Pliocene Demise of the Giant Volant Birds

Version 1 : Received: 3 March 2021 / Approved: 4 March 2021 / Online: 4 March 2021 (14:12:04 CET)

How to cite: Cannell, A. Into Thinner Air: The Pliocene Demise of the Giant Volant Birds. Preprints 2021, 2021030164 (doi: 10.20944/preprints202103.0164.v1). Cannell, A. Into Thinner Air: The Pliocene Demise of the Giant Volant Birds. Preprints 2021, 2021030164 (doi: 10.20944/preprints202103.0164.v1).

Abstract

Three genera of very large volant birds existed for most of the Pliocene: the Pelagornithidae seabirds; the large North American Teratornithidae and the stork Leptoptilos falconeri in Africa and Asia. All became extinct around 3 Ma. The reasons for their demise are puzzling, as the Pelagornithidae had a world-wide evolutionary history of more than 50 Ma, smaller teratorns were still extant in the Holocene and smaller stork species are still globally extant. Extant large birds have a common critical takeoff airspeed suggesting a biomechanical limit in terms of power, risk and launch speed, and simulations of the flight of these extinct species suggest that at 1 bar they would have exceeded this value. Estimates for the Late Pliocene atmospheric density are derived from marine and terrestrial isotopes as well as resin chemistry, both approaches suggesting a value of about 1.2 bar, which drops to present levels during the period 3.3 to 2.6 Ma, thus a loss in atmospheric density may have caused biomechanical and ecological stress contributing to their extinction and/or development of smaller forms. This hypothesis is examined in terms of a possible mechanism of atmospheric mass loss and how this would be seen in the geological record. At 1.2 bar all the extinct species present takeoff airspeeds similar to large extant volant birds and which match the expected power and kinetic energy levels.

Subject Areas

Pelagornithidae; Teratornithidae; takeoff airspeed; paleo-air density; extinction

Comments (0)

We encourage comments and feedback from a broad range of readers. See criteria for comments and our diversity statement.

Leave a public comment
Send a private comment to the author(s)
Views 0
Downloads 0
Comments 0
Metrics 0


×
Alerts
Notify me about updates to this article or when a peer-reviewed version is published.
We use cookies on our website to ensure you get the best experience.
Read more about our cookies here.