''Parahesperornis'' is a genus of prehistoric

flightless bird Flightless birds are birds that cannot Bird flight, fly, as they have, through evolution, lost the ability to. There are over 60 extant species, including the well-known ratites (ostriches, emus, cassowary, cassowaries, Rhea (bird), rheas, an ...

s from the Late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

. 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 ''Hesperornis'' (meaning "western bird") is a genus of cormorant-like Ornithuran that spanned throughout the Campanian age, and possibly even up to the early Maastrichtian age, of the Late Cretaceous period. One of the lesser-known discoverie ...

''. Remains are known from central

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, namely the former shallows of the

Western Interior Seaway The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, or the Western Interior Sea) was a large inland sea (geology), inland sea that existed roughly over the present-day Great Plains of ...

in Kansas. Found only in the upper

Niobrara Chalk The Niobrara Formation , also called the Niobrara Chalk, is a Formation (stratigraphy), geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the La ...

, these are from around the

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by ...

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

boundary, 85–82 million years ago (mya).

''Parahesperornis alexi'' (Martin, 1984) was long lumped with specimen YPM 1478, described initially as ''Hesperornis gracilis'' and later moved to the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus ''Hargeria'' (Lucas, 1903). It then turned out that this genus' description actually referred to specimen KUVP 2287, which eventually became the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

of ''P. alexi''. Nonetheless, the

taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

description of ''Hargeria'' was about ''"Hesperornis" gracilis'' exclusively, and thus despite the misidentification it applies to YPM 1478, the

of ''"H." gracilis''. This mistake was rectified by later authors, who sank ''Hargeria'' back into ''Hesperornis''.Bell, A. and Everhart, M.J. (2009). "A new specimen of ''Parahesperornis'' (Aves: Hesperornithiformes) from the Smoky Hill Chalk (Early Campanian) of Western Kansas." ''Transactions of the Kansas Academy of Science'', 112(1/2): 7-14. In 2017, ''

Asiahesperornis ''Asiahesperornis'' is a prehistoric foot-propelled diving bird, diving toothed flightless bird genus from the Late Cretaceous. The single known species is ''Asiahesperornis bazhanovi''. It lived in what today is Kazakhstan, at its time the shore ...

'' was considered as a possible synonym of ''Parahesperornis''. ''Parahesperornis'' was a member of the

Hesperornithes Hesperornithes is an extinct and highly specialized group of aquatic Avialae, avialans closely related to the ancestors of modern birds. They inhabited both marine and freshwater habitats in the Northern Hemisphere, and include genus, genera such ...

, flightless toothed seabirds of the

and more specifically in the main lineage, close to ''

''.Mortimer (2004) Possibly the genus extended into the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

, to less than 80 mya. In any case, there are two very similar

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s from the

Nemegt Formation The Nemegt Formation (also known as Nemegtskaya Svita) is a geological formation in the Gobi Desert of Mongolia, dating to the Late Cretaceous. The formation consists of river channel sediments and contains fossils of fish, turtles, crocodilians ...

(

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

or possibly late Campanian, around 76–66 mya), which were found at Tsagaan Kushu (

Mongolia Mongolia is a landlocked country in East Asia, bordered by Russia to the north and China to the south and southeast. It covers an area of , with a population of 3.5 million, making it the world's List of countries and dependencies by po ...

). Both are

distal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

ends of tibiotarsi, and they seem certainly more similar to the bones of

Hesperornithiformes Hesperornithes is an extinct and highly specialized group of aquatic avialans closely related to the ancestors of modern birds. They inhabited both marine and freshwater habitats in the Northern Hemisphere, and include genera such as ''Hesperorn ...

and (due to the smallish size) to ''Parahesperornis'' specifically. However, they are not very diagnostic regardless, and the diversity of ''Parahesperornis'' remains enigmatic. In 2015, a species-level phylogenetic analysis found the following relationships among hesperornitheans.

Footnotes

References

* Lucas, F. A. 1903. Notes on the osteology and relationships of the fossil birds of the genera ''Hesperornis'', ''Hargenia'', ''Baptornis'', and ''Diatryma''. Proc. U.S. National Mus. 26:545-556. * Martin, L. 1984. A new Hesperornithid and the relationships of the Mesozoic birds. Transactions of the Kansas Academy of Science 87:141-150. * (2004): The Theropod Database
Phylogeny of taxa
Retrieved 2013-MAR-02. * Williston. S.W. 1898. Birds. University Geological Survey of Kansas 4(2):43-64.

External links

Kansas Geological Survey The Kansas Geological Survey (KGS) is a research and service division of the University of Kansas, charged by statute with studying and providing information on the geologic resources of Kansas. The KGS has no regulatory authority and does not ta ...

''Parahesperornis alexi'' reconstruction
Retrieved 2007-NOV-04. * Oceans of Kansas Paleontology

Retrieved 209-JAN-15 *

UC Davis The University of California, Davis (UC Davis, UCD, or Davis) is a Public university, public Land-grant university, land-grant research university in Davis, California, United States. It is the northernmost of the ten campuses of the University ...

Moveable 3D rendering of ''P. alexi'' tibiotarsus
Digitized from KUVP 2287. Requires Java, IFC or 3DC plugin. Retrieved 2007-NOV-04. Bird genera Hesperornithes Extinct flightless birds Late Cretaceous birds of North America {{paleo-bird-stub