Everyone interested in animals must, by law, have set eyes on that iconic image of palaeornithologist Kenneth E. Campbell standing next to a life-sized silhouette of the immense Argentinean teratornithid Argentavis magnificens [the image is shown below]. At the International Bird of Prey Centre, Gloucestershire (UK), I quite liked the wooden silhouette of an Andean condor Vultur gryphus and, in the image here, Tone is standing next to it, looking as much like Campbell as she is able. An actual live Andean condor can just about be seen sitting in the enclosure in the background. An Andean condor isn’t quite as big as Argentavis: the latter had a wingspan of over 6 m and probably weighed around 80 kg (Campbell & Tonni 1983, Vizcaíno & Fariña 1999, Palmqvist & Vizcaíno 2003, Chatterjee et al. 2007) whereas the former might have a wingspan of just over 3 m and a heavy male may weigh up to 12 kg (in contrast to most other raptors, male condors are bigger than females).
While they’ve often been imagined or depicted as mega-condors, nobody really seems that sure what Argentavis and its relatives – the teratornithids or teratorns – really are. Most recent papers that express an opinion include them in Ciconiiformes, but never with an adequate explanation: it’s all based on the idea that (1) teratorns are close relatives of New World vultures (aka vulturids or cathartids), and (2) that New World vultures are close kin of storks, and hence part of Ciconiiformes (well, Sibley and Ahlquist complicated things by making Ciconiiformes far more inclusive than it is in its traditional sense). The idea that storks and New World vultures are each other’s closest relatives is no longer popular by the way (see Livezey & Zusi 2007 for a review). And are teratorns close to New World vultures? It looks likely, but someone still needs to examine this question in detail (Emslie (1988a) was able to list multiple derived characters shared by teratorns and New World vultures, most of them present in the tarsometatarsus).
Vultur is restricted to South America* and probably evolved here from an ancestor that invaded the continent during the American Interchange: fossils indicate that condors are ancestrally North American, and Breagyps clarki from the Pleistocene of California shares several skeletal characters with Vultur that are not present in other condors (Emslie 1988a, b). During the Pliocene, V. gryphus was more widespread in South America: its decline has been blamed on climatic changes and the loss of the megafauna (Tambussi & Noriega 1999).
* In 1988, several individuals were released in California in order to test how successful the possible release of captive-bred Californian condors Gymnogyps californianus might be. These birds were later captured and released back into South America.
So much more to say. But, again, this was meant to be a text-lite ‘picture of the day’ post. D’oh. For previous Tet Zoo articles on raptors see the ver 1 articles When eagles go bad, When eagles go bad, one more time, harrier hawks, and the still incomplete ‘series’ on Haast’s eagle.
Refs – –
Campbell, K. E. & Tonni, E. P. 1983. Size and locomotion in teratorns (Aves: Teratornithidae). The Auk 100, 390-403.
Chatterjee, S., Templin, R. J. & Campbell, K. E. 2007. The aerodynamics of Argentavis, the world’s largest flying bird from the Miocene of Argentina. Proceedings of the National Academy of Sciences 104, 12398-12403.
Emslie, S. D. 1988a. The fossil history and phylogenetic relationships of condors (Ciconiiformes: Vulturidae) in the New World. Journal of Vertebrate Paleontology 8, 212-228.
– . 1988b. An early condor-like vulture from North America. The Auk 105, 529-535.
Livezey, B. C. & Zusi, R. L. 2007. Higher-order phylogeny of modern birds (Theropoda, Aves: Neornithes) based on comparative anatomy. II. Analysis and discussion. Zoological Journal of the Linnean Society 149, 1-95.
Palmqvist, P. & Vizcaíno, S. F. 2003. Ecological and reproductive constraints of body size in the gigantic Argentavis magnificens (Aves, Theratornithidae [sic]) from the Miocene of Argentina. Ameghiniana 40, 379-385.
Tambussi, C. P. & Noriega, J. I. 1999. The fossil record of condors (Ciconiiformes: Vulturidae) in Argentina. Smithsonian Contributions to Paleobiology 89, 177-184.
Vizcaíno, S. F. & Fariña, R. A. 1999. On the flight capabilities and distribution of the giant Miocene bird Argentavis magnificens (Teratornithidae). Lethaia 32, 271-278.