Palintropus
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| Palintropus Fossil range: Maastrichtian) |
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Palintropus retusus |
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Apatornis retusus |
Palintropus is a prehistoric bird genus from the Late Cretaceous. It lived in the Maastrichtian, some 69[verification needed] million years ago. Its remains were found in the Lance Formation of North America. A single species has been named (Palintropus retusus) but more material of undescribed species is known.
Its relationships are not well determined, mainly due to the long-standing paucity of material. Two major theories have been established: Like many of the birds of the subtropical coastlands of the Western Interior Seaway - maybe a bit like eastern Australia today - it is sometimes believed to be an early member of the Charadriiformes (waders, gulls, auks, etc. See also "Graculavidae"). However, an alternate theory is that it is a galliform, perhas a quercymegapodiid.
The quercymegapodiid hypothesis is supported by cladistic analysis[1]. This may be of rather limited value here, because of the paucity of studied material[2], but placement there is also supported by comprehensive qualitative analysis. Notable differences exist to other known quercymegapodiidas, but these are not crass enough to suggest against a close relationship between that family and Palintropus. Altogether, the most satisfying and quite robust hypothesis is that if P. retusus was not actually an early quercymegapodiid, it was basal to that group.
The quercymegapodiids, an extinct group of prehistoric Galliformes, lived apparently on both sides of the Atlantic, which by then was narrower, with only a few straits separating Europe and North America in the temperate Greenland region. They seem to have been inhabitants of warm regions as they seem also have to occurred in Brazil, and it is quite likely that they were also found in or even originated in Africa from where almost no contemporary bird fossils are known. Their undisputed fossil record starts in the Eocene.
Given that Anseriformes are now known to have radiated into the families still present today, it is suspected that by the end of the Cretaceous, at least 4 lineages of Galliformes existed as distinct: Megapodiidae, Cracidae, Phasianidae and the Quercymegapodiidae. Consequently, the possibility that the present species was also a quercymegapodiid is well in agreement with the phylogenetic and biogeographic data.
[edit] Footnotes
[edit] References
- Mortimer, Michael (2004): The Theropod Database: Phylogeny of taxa. Retrieved 2007-OCT-29.
- Varricchio, David J. (2002): A new bird from the Upper Cretaceous Two Medicine Formation of Montana. Canadian Journal of Earth Sciences 39(1): 19-26. HTML abstract
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