| Tsaagan | |
|---|---|
 | |
| Holotype skull | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | †Dromaeosauridae |
| Clade: | †Eudromaeosauria |
| Subfamily: | †Velociraptorinae |
| Genus: | †Tsaagan Norellet al., 2006 |
| Species: | †T. mangas |
| Binomial name | |
| †Tsaagan mangas Norellet al., 2006 | |
Tsaagan (meaning "white") is agenus ofdromaeosauriddinosaur from theDjadokhta Formation of theLate Cretaceous ofMongolia.
The holotype ofTsaagan was discovered in 1996 and first identified as a specimen ofVelociraptor. After aCAT-scan in May 1998 it was concluded that it represented a new genus. In December 2006 itstype species was named and described byMark Norell,James Clark,Alan Turner,Peter Makovicky,Rinchen Barsbold andTimothy Rowe. Thespecies name,Tsaagan mangas, should be read as a whole with the generic name qualifying thespecific epithet, and is derived from the Mongolian words for "white monster" (цагаан мангас),[1] although with an accidental misspelling of the wordTsagaan.
Theholotype specimen,IGM 100/1015, was found near Xanadu inÖmnögovi Province in layers of the Djadokhta Formation dating to theCampanian, about 75 million years ago. It consists of a well-preserved skull and series of ten neck vertebrae as well as a damaged left shoulder girdle. It is the only specimen found ofTsaagan and belonged to an adult individual.[1]
Tsaagan was a medium-sized dromaeosaurid. In 2010Gregory S. Paul estimated its length at 2 metres (6.6 ft), its weight at 15 kilograms (33 lb).[2] The skull in general appearance resembles that ofVelociraptor but differs from it in many details. It is more robust and smooth on top; unique derived traits,autapomorphies, include long paroccipital processes and basipterygoids at the back of the skull and ajugal touching thesquamosal.[1]
Tsaagan is a member of the groupDromaeosauridae. Acladistic analysis by Norellet al. originally indicated it was more precisely a member of theVelociraptorinae.[1] In 2010 an analysis showed it was closely related toLinheraptor;[3] subsequently Senter (2011) and Turner, Makovicky and Norell (2012) argued thatLinheraptor exquisitus is in fact a junior synonym ofTsaagan mangas.[4][5] Xu, Pittmanet al. (2015) reject this synonymy by responding to the counterarguments proposed using new and existing details ofLinheraptor's anatomy.[6]
Below are the results for the Eudromaeosauriaphylogeny based on thephylogenetic analysis performed by Currie and Evans in 2019:[7]
Tsaagan represents the only dromaeosaurid remains (other than isolated teeth) known from theUkhaa Tolgod region, though another dromaeosaurid,Velociraptor, is known from the sameDjadokhta Formation. Animals that may have shared the same habitat withTsaagan includeProtoceratops,Shuvuuia, the smallmammalZalambdalestes, themultituberculate mammalKryptobaatar, as well as several lizards and two yet-undescribed species oftroodontid and dromaeosaurid.[1]
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