Superregnum: Eukaryota
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Cladus: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Infraclassis: Archosauromorpha
Cladus: Crurotarsi
Divisio: Archosauria
Subsectio: Ornithodira
Subtaxon: Dinosauromorpha
Cladus: Dinosauria
Ordo: Saurischia
Cladus: Theropoda
Cladus: Neotheropoda
Infraclassis: Aves
Cladus: Euavialae
Cladus: Avebrevicauda
Cladus: Pygostylia
Cladus: Ornithothoraces
Cladus: Euornithes
Magnordo: Hesperornithes
Ordo: Hesperornithiformes
Familia: Incertae sedis
Genus: †Potamornis
Species: P. skutchi
Name
Potamornis Elzanowski, G.S. Paul & Stidham, 2000
References
Elzanowski, A., Paul, G.S. & Stidham, T.A. 2000. An avian quadrate from the Late Cretaceous Lance Formation of Wyoming. Journal of Vertebrate Paleontology 20(4): 712–719. DOI: 10.1671/0272-4634(2000)020[0712:AAQFTL]2.0.CO;2 Reference page.
Potamornis is a prehistoric bird genus that dated back to the late Maastrichtian age of the late Cretaceous period. Its scrappy remains were found in the Lance Formation at Buck Creek, USA, and additional possible remains were found in the upper Hell Creek Formation of Montana, dated to the Danian age of the Paleogene period, though these may have been reworked.[1] A single species was named and described in 2001: Potamornis skutchi.[2]
This was almost certainly a member of the Hesperornithes, the hefty and toothed flightless diving birds of the Mesozoic seas. Its precise relationships are not all too clear; the quadrate bone is unique in some respects but apparently shares more apomorphies with the family Hesperornithidae - the "typical" Hesperornithes - in cladistic analysis.[3] Consequently, it might be considered a fossil hesperornithid with a different feeding specialization. Though it was heavily built like many (flying and flightless) diving birds, it weighed perhaps 1.5 or 2 kg. This raises the possibility that the Hesperornithes not only included flying members (see also Enaliornis), but that their families might have evolved flightlessness independently.
Footnotes
Mortimer (2004)
A. Elzanowski, G.S. Paul, and T.A. Stidham, 2001, "An avian quadrate from the Late Cretaceous Lance Formation of Wyoming", Journal of Vertebrate Paleontology 20(4): 712-719
Mortimer (2004)
References
Michael Mortimer (2004): The Theropod Database: Phylogeny of taxa. Retrieved 2013-MAR-02.
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