| Cretornis | |
|---|---|
 | |
| Partial wing ofCretornis hlavaci | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Order: | †Pterosauria |
| Suborder: | †Pterodactyloidea |
| Clade: | †Nyctosauromorpha |
| Genus: | †Cretornis Frič, 1881 |
| Type species | |
| †Cretornis hlavaci | |
| Synonyms | |
| |
Cretornis is apterosaurgenus from the lateCretaceous period (Turonian stage) of what is now theJizera Formation in theCzech Republic, dating to about 92 million years ago. It only contains a single species,Cretornis hlavaci.
The fossils were discovered in1880 by workers at asandstone quarry inZářecká Lhota near the town ofChoceň, who were getting gravel to repair a local road. A certain Mrs. Tomková, a croupier from Choceň, then alerted František Hlaváč, a Choceň pharmacist and fossil collector, to the find. He recognised exceptionality of that one, secured the rest of the fossils and then sent them to naturalist ProfessorAntonín Frič in Prague. In 1881,Antonín Frič identified it as a prehistoric toothed bird the size of a recentswan and named it as thetype speciesCretornis Hlaváči.[1] The generic name is derived fromLatincreta, "chalk", in reference to the Cretaceous, and Greek ὄρνις,ornis, "bird", as Frič originally thought that the fossil bones belonged to some kind of ancient toothed bird (similar to the genusIchthyornis). Thespecific name honors Hlaváč.[2]
Today, the holotype fossils of this pterosaur are stored in the National Museum in Prague. There is also unconfirmed information that similar bones (perhaps also pterosaur bones) were found in other places around the quarry before and during this discovery, but later they were apparently lost.
Afterwards it was realized that the find represented some pterosaur. The name was incorrectly emended byRichard Lydekker intoOrnithochirus hlavatschi Fritsch 1881, in 1888.[3] As scientific species names are not allowed to containdiacritical signs, the specific name had to be transcribed. Lydekker chose to write it as if it, and Frič himself, were German, asBohemia at the time was under a strong German cultural influence. Frič, an ethnic Czech, in 1905 ultimately used the correct transcriptionOrnithocheirus hlavaci.[4][5]
Since 1905, thetaxon was typically considered anomen dubium.[6] In 2010 however, Russian paleontologist Alexandr Averianov concluded that it should be possible to determine unique traits.[7] In 2015 he and Czech paleontologist Boris Ekrt published a new description, concluding thatCretornis was a valid taxon.[8]
Cretornis is known from theholotype, presently preserved in the collection of theNárodní muzeum (National Museum) inPrague as "Object 10". It was found in what Frič called theMittlere Iserschichten, today known as theJizera Formation, dating from the Turonian. It is a partial skeleton lacking the skull. It contains a completehumerus (upper arm bone), anulna, radius, wrist and two phalanges of the wing finger.[7]
Based on comparison with its relatives, the wingspan ofC. hlavaci has by Averianov been estimated at 1.5 to 1.6 meters (4.9 to 5.2 ft).[8] The humerus is 76 millimeters (3 in) in length.[7]
In 2015, Averianov indicated a singleautapomorphy, unique derived trait: the distal part of the humerus has a diamond-shaped cross-section.[8]
Cretornis was classified as a species in the genusOrnithocheirus in the nineteenth century. In 1997 Coralia-Maria Jianu suggested it belonged to thePteranodontidae.[9] In 2010, Averianov thought is it was a member of theAzhdarchidae. More detailed comparisons of the wing bones led Averianov to conclude in 2015 that they belonged to a non-azhdarchidazhdarchoid, probably a member of the groupNeoazhdarchia with which it has many features in common.[7][8] It is probably more advanced than theThalassodromidae, and shares withMontanazhdarcho the trait that the distal part of the ulna has a joint surface that is placed more proximal than the tubercle.[8] In 2018, paleontologist Nicholas Longrich and colleagues had recoveredCretornis within the familyNyctosauridae, in a more derived position thanAlamodactylus andVolgadraco, this contradicts its position within the Azhdarchoidea.[10] The cladogram of their analysis is shown below:
However, subsequent phylogenetic analyses placedCretornis as a pteranodontian outsideNyctosauridae.[11][12]
