- Gastornithiformes
Taxobox
name = Gastornithiformes
fossil_range =Late Paleocene -middle Eocene
image_width = 200px
image_caption = Life restoration of "Gastornis " (formerly "Diatryma")
regnum =Animalia
phylum =Chordata
classis =Aves
subclassis =Neornithes
infraclassis =Neognathae
superordo =Galloanserae ?
ordo = †Gastornithiformes
ordo_authority =
familia = †Gastornithidae
familia_authority = Fürbringer,1888
subdivision_ranks =Genera
subdivision ="Gastornis "
"Omorhamphus "
"Zhongyuanus "Gastornithiformes are an order of prehistoric
bird s. The birds from this group lived from thePaleocene to theEocene and were spread out across Asia, Europe, and North America. All the birds were very large birds that were flightless, similar to anostrich but more heavily built and with a huge beak. They are generally assumed to be predators, but this is conjectural. It is likely though that they included a considerable amount of meat in their diet, although they may have been scavengers rather than active hunters.There is no agreement on the relationships of the Gastornithiformes. They were long and still are sometimes placed with the
Gruiformes as a family Gastornithidae. The Gruiformes seemparaphyletic though, with some lineages that are exclusivelyGondwana n but apparently not closely related to cranes, rails and allies which are common in Eurasia andAfrica but far less so in the Americas. Some others, probably unrelated to either group, were very diverse in theAmericas but prehistorically also occurred in Europe. Nothing is known of the ancestry of the Gastornithiformes; judging frombiogeography , a relationship with either the true Gruiformes or the "Americas" lineage (which might include theseriema s and the phorusrhacids) is possible.However, the early occurrence of the diatrymas in the fossil record poses problems. These animals were highly
apomorph ic and thus the lineage must have evolved for significant time after diverging from their closest known relatives. Most purported relatives are not known nor suspected to have been so highly distinct at the time when the diatrymas lived.More recently, most consider the closest living relatives of the Gastornithiformes to be the
Anseriformes (waterfowl andscreamer s). The present birds would thus be members of the fowlclade ,Galloanserae . The clade name Anserimorphae has been proposed for the diatrymas and the Anseriformes, as opposed to birds closer toGalliformes . As Galloanserae are known to have reached some diversity in theLate Cretaceous already, this scenario very plausibly explains the extreme adaptations of the diatrymas: they would have evolved for some 15-25 million years at least after diverging from the ancestors of the Anseriformes.Moreover, in this case the
Neogene mihirungs would have recapitulated the gigantism of the diatrymas, though based on a more advanced anseriform (i.e., more "gooselike" as regards details of theirosteology ) ancestor. This would be an outstanding example ofconvergent evolution which was very close to being homologous phylogenetically but still a true convergence ofphene s in most aspects.Apart from the
genera listed above, there are some indeterminate gastornithiform fossils:
* Gastornithidae gen. et sp. indet. (Paleocene of Walbeck, Germany) - possibly "Gastornis"
* Gasthornithidae gen. et sp. indet. YPM PU 13258 (Willwood Early Eocene of Park ["Parly" in Wetmore (1933) is a misprint.] County, USA) - possibly juvenile "Gastornis giganteus" [Wetmore (1933)]
* "Diatryma" cotei" (middle-Late Eocene of France)Mlíkovský (2002)]Footnotes
References
* (1967): Catalogue of Fossil Birds: Part 3 (Ralliformes, Ichthyornithiformes, Charadriiformes). "Bulletin of the Florida State Museum" 11(3). [http://fulltext10.fcla.edu/cgi/t/text/text-idx?cc=feol;subview=fullcitation;idno=UF00001511 PDF or JPEG fulltext]
* (2002): "Cenozoic Birds of the World, Part 1: Europe". Ninox Press, Prague. ISBN 80-901105-3-8 [http://www.nm.cz/download/JML-18-2002-CBE.pdf PDF fulltext]
* (1933): Fossil Bird Remains from the Eocene of Wyoming. "Condor" 35(3): 115-118. [http://elibrary.unm.edu/sora/Condor/files/DJVU/v035n03/P0115-P0118.djvu DjVu fulltext] [http://elibrary.unm.edu/sora/Condor/files/issues/v035n03/p0115-p0118.pdf PDF fulltext]
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