Parahesperornis

:"Hargeria redirects here. This is also an (invalid) name of a genus of tanaidacean crustaceans in the family Leptocheliidae."Taxobox
name = "Parahesperornis"
status = fossil
fossil_range = Late Cretaceous
regnum = Animalia
phylum = Chordata
classis = Aves
subclassis = Hesperornithes
ordo = Hesperornithiformes
familia = Hesperornithidae
familia_authority =
genus = "Parahesperornis"
genus_authority =
subdivision_ranks = Species
subdivision ="Parahesperornis alexi"
"Parahesperornis gracilis" and see text
synonyms =Of "Parahesperornis":
* "Hargeria"
F.A. Lucas, 1903----Of "P. gracilis":
* "Hargeria gracilis"
* "Hesperornis gracilis"

"Parahesperornis" is a prehistoric flightless bird genus from the Late Cretaceous. Its range in space and time may have been extensive, but its remains are rather few and far between, at least compared with its contemporary relatives in "Hesperornis". Remains are known from central North America, namely the former shallows of the Western Interior Seaway. Found mainly in the upper Niobrara Chalk, these are from around the Coniacian-Santonian boundary, 85-82 million years ago (mya).

"Parahesperornis alexi" was long lumped with specimen YPM 1478, described initially as "Hesperornis gracilis" and later moved to the monotypic genus "Hargeria". It then turned out that this genus' description actually referred to specimen KUVP 2287, which eventually became the holotype of "P. alexi". Nonetheless, the taxon the description of "Hargeria" was about was "Hesperornis" gracilis" exclusively, and thus despite the misidentification it applies to YPM 1478, the holotype of "H." gracilis". It is now believed, contrary to the initial reassessment, that YPM 1478 is also referable to "Parahesperornis", resulting in "Parahesperornis gracilis" as the name now usually seen in scientific publications; though some doubts remain this seems to be correct Mortimer (2004)] .

"Parahesperornis" was a member of the Hesperornithes, flightless toothed seabirds of the Cretaceous and more specifically in the main lineage, close to "Hesperornis". Possibly the genus extended into the Campanian, to less than 80 myaVerify source|date=November 2007. In any case, there are two very similar fossils from the Nemegt Formation (Maastrichtian or possibly late Campanian, around 76-65 mya, which were found at Tsagaan Kushu (Mongolia). Both are distal ends of tibiotarsi, and they seem certainly more similar to the bones of Hesperornithiformes and (due to the smallish size) to "Parahesperornis" specifically. However, they are not very diagnostic regardless, and the diversity of "Parahesperornis" remains enigmatic.

Footnotes

References

* (2004): The Theropod Database: [http://home.comcast.net/~eoraptor/Phylogeny%20of%20Taxa.html Phylogeny of taxa] . Retrieved 2008-AUG-14.

External links

* Kansas Geological Survey: [http://www.kgs.ku.edu/Publications/Bulletins/ED15/gifs/fig11.gif"Parahesperornis alexi" reconstruction] . Retrieved 2007-NOV-04.
* UC Davis: [http://3dmuseum.geology.ucdavis.edu/frame.html?3DVB0001_MAIN.htm~mainFrame Moveable 3D rendering of "P. alexi" tibiotarsus] . Digitized from KUVP 2287. Requires Java, IFC or 3DC plugin. Retrieved 2007-NOV-04.