Saturday 6 April 2013

A fossil Vulture from the Miocene of Nebraska.

The Old World Vultures are divided into two subfamilies, the Gypaetinae and the Aegyptiinae, both of which belong to the Bird of Prey family, Accipitridae, which also includes Eagles, Hawks and other Birds of Prey. The New World Vultures and Condors are more distantly related, and placed in a separate family, the Cathartidae, within the order Accipitriformes, which also includes the Ospreys and Secretary Birds. Both groups of Old World Vultures are currently restricted to Africa and Eurasia, but are known in the fossil record of North America.

In a paper published in the journal PLoS One on 9 November 2012, Zihui Zhang of the College of Life Sciences at Capital Normal University in Beijing, Alan Feduccia of the Department of Biology at the University of North Carolina, and Helen James of the Department of Vertebrate Zoology at the National Museum of Natural History in Washington DC, describe a new Gypaetinid Vulture from the Late Miocene of Nebraska.

The specimen was found in a 2 m deep volcanic ash bed, originating from a major eruption that occurred in Idaho in the Late Miocene, close to the town of Orchard in Antelope County, Nebraska. It is placed within the subfamily Gypaetinae, which includes the modern Palm-nut Vulture, Egyptian Vulture and Lammergeier, and which is previously known in North America from Pleistocene deposits at Rancho la Brea.

The new species is given the name Anchigyps voorhiesi, meaning Voorhies' Almost-Vulture, after Michael Voorheis, who discovered the Orchard ash beds and led the excavation of fossils from them. The species is described from two extremely fragmentary specimens, one comprising a three leg-bones, one wing-bone and part of the lower beak, the other a single leg-bone. This is quite common with fossils of birds, since the skeleton is extremely fragile, with the most robust bones in the legs.

Anchigyps voorhiesi. A, tip and part of the left ramus of the mandible. B–D, right ulna in ventral (B), dorsal (C) and cranial (D) views. E–H, left tibiotarsus in anterior (E), posterior (F), lateral (G) and medial (H) views. I–J, right tarsometatarsus in anterior (I) and posterior (J) views. K–L, left tarsometatarsus in anterior (K) and posterior (L) views. Abbreviations: CC, crista cnemialis cranialis; CD, cotyla dorsalis; CDU, condylus dorsalis ulnae; CF, crista fibularis; CLH, crista lateralis hypotarsi; CMH, crista medialis hypotarsi; CV, cotyla ventralis; DEL, depressio epicondylaris lateralis; EL, epicondylus lateralis; EM, epicondylaris medialis; FG, facies gastrocnemialis; FMI, fossa metatarsi I; FVD, foramen vasculare distale; FVP, foramina vascularia proximalia; IB, impressio m. brachialis; IIL,incisure intertrochlea lateralis; IIM, incisure intertrochlea medialis; IR, incisure radialis; LE, linea extensoria; LFB, linea m. fibularis brevis; OL, olecranon; PS, pons supratendineus; SF, sulcus flexorius; TC, tuberculum carpale; TFB, tuberculum m. fibularis brevis; TL, tuberculum lig. collateralis ventralis; TRE, tuberositas retinaculi extensori; TTC, tuberositas m. tibialis cranialis. Scale bars equal 1 cm. Zhang et al. (2012).

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