Azhdarcho

Taxobox
name = "Azhdarcho"
fossil_range = Late Cretaceous


image_width = 200px
image_caption =
regnum = Animalia
phylum = Chordata
classis = Sauropsida
ordo = Pterosauria
subordo = Pterodactyloidea
familia = Azhdarchidae
genus = "Azhdarcho"
genus_authority = Nessov, 1984
subdivision_ranks = Species
subdivision ="A. lancicollis" Nessov, 1984 (type)

"Azhdarcho" (IPA pronunciation: [adʒˈdarχɒ] ) is a genus of pterodactyloid pterosaur from the late Cretaceous Period (Upper Turonian-Coniacian, about 89 million years ago) of Uzbekistan. It is known from fragmentary remains including the distinctive, elongated neck vertebrae that characterizes members of the family Azhdarchidae, which also includes such giant pterosaurs as "Quetzalcoatlus". The name "Azhdarcho" comes from the Uzbek word "azhdarkho", the name of a dragon in Uzbek mythology. The specific name "A. lancicollis" derives from the Latin words "lancea" (meaning "lance" or "spear") and "collum" ("neck").

Discovery and Species

The fossil remains of "Azhdarcho" were recovered in the Kyzyl Kum desert by L.A. Nessov during expeditions to Central Asia in 1974-1981. The type specimen consists of several neck vertebrae, elements from the wing and leg, and pieces of the jaw. These specimens, along with other vertebrate fossils collected during the expeditions, were deposited at the F.N. Chernyshev Central Geologic Exploration Museum in St. Petersberg, and given the catelogue number TsNIGRmuzey 1/11915.Nessov, L. A. (1984). [" [http://www.azhdarcho.com/Art/Paleoart/azhdarch3.htm Upper Cretaceous pterosaurs and birds from Central Asia.] "] "Paleontologicheskii Zhurnal", 1984(1), 47-57.]

In his description of the type specimen of "Azhdarcho lancicollis", Nessov noted its distinctive neck vertebrae, which are extremely elongated and round in cross section at mid-length. He pointed out similar characteristics in several other pterosaurs, and used them to erect the new subfamily Azhdarchinae, within the Pteranodontidae. Nessov also referred "Quetzalcoatlus" and "Arambourgiania" (then known as "Titanopteryx") to this subfamily, which was subsequently re-classified as the family Azhdarchidae. He also suggested that similar, thin-walled pterosaur bones from the Lance Formation of Wyoming could be assigned to a species of "Azhdarcho", using this as evidence of commonalities between the fauna of Late Cretaceous central Asia and western North America. However, subsequent research has not followed this suggestion, and "A. lancicollis" is the only currently recognized species of "Azhdarcho".cite book |last=Unwin |first=David M. |title=The Pterosaurs: From Deep Time |year=2006 |publisher=Pi Press |location=New York |isbn=ISBN 0-13-146308-X |pages=273]

Paleoecology

In the original description of "Azhdarcho", Nessov noted that because of the way the vertebrae articulated, the pterosaur would have had very limited flexibility in the neck. "Azhdarcho" could not rotate its neck at all, though it could flex the neck vertically to a certain degree. Nessov suggested that pterosaurs like "Azhdarcho" may have fed in a manner similar to the modern Skimmer, with their long necks allowing them to scoop prey from the water's surface and small depths without needing to dive. However, recent research has shown that skimming requires more energy and anatomical specializations than previously thought, and that large pterosaurs like "Azhdarcho" probably were not capable of skimming.Humphries, S., Bonser, R.H.C., Witton, M.P., and Martill, D.M. (2007). " [http://biology.plosjournals.org/archive/1545-7885/5/8/pdf/10.1371_journal.pbio.0050204-L.pdf Did pterosaurs feed by skimming? Physical modelling and anatomical evaluation of an unusual feeding method.] " "PLoS Biology", 5(8): e204.] The long neck would also have allowed azhdarchids to hunt for food in the water or on the bottom while swimming, or to hunt poorly-flying vertebrates in the air, though Nessov also suggested that the animal would have needed stable weather conditions to fly well, and suggested azhdarchid habitats needed to be dominated by even, mild winds.

References