| Parahesperornis | |
|---|---|
 | |
| Replica skeleton | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | Avialae |
| Clade: | †Hesperornithes |
| Family: | †Hesperornithidae |
| Genus: | †Parahesperornis Martin, 1984 |
| Type species | |
| †Parahesperornis alexi Martin, 1984 | |
| Other species | |
| |
| Synonyms | |
Parahesperornis is a genus of prehistoricflightless birds from the LateCretaceous. 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 inHesperornis. Remains are known from centralNorth America, namely the former shallows of theWestern Interior Seaway in Kansas. Found only in the upperNiobrara Chalk, these are from around theConiacian-Santonian boundary, 85–82 million years ago (mya).
Parahesperornis alexi (Martin, 1984) was long lumped with specimenYPM 1478, described initially asHesperornis gracilis and later moved to themonotypic genusHargeria (Lucas, 1903). It then turned out that this genus' description actually referred to specimenKUVP 2287, which eventually became theholotype ofP. alexi. Nonetheless, thetaxon description ofHargeria was about"Hesperornis" gracilis exclusively, and thus despite the misidentification it applies to YPM 1478, theholotype of"H." gracilis. This mistake was rectified by later authors, who sankHargeria back intoHesperornis.[1]
In 2017,Asiahesperornis was considered as a possible synonym ofParahesperornis.
Parahesperornis was a member of theHesperornithes, flightless toothed seabirds of theCretaceous and more specifically in the main lineage, close toHesperornis.[2] Possibly the genus extended into theCampanian, to less than 80 mya[citation needed]. In any case, there are two very similarfossils from theNemegt Formation (Maastrichtian or possibly late Campanian, around 76–66 mya), which were found atTsagaan Kushu (Mongolia). Both aredistal ends oftibiotarsi, and they seem certainly more similar to the bones ofHesperornithiformes and (due to the smallish size) toParahesperornis specifically. However, they are not very diagnostic regardless, and the diversity ofParahesperornis remains enigmatic.
In 2015, a species-level phylogenetic analysis found the following relationships among hesperornitheans.[3]
| Hesperornithes |
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