''Tsaagan'' (meaning "white") is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

dromaeosaurid Dromaeosauridae () is a family (biology), family of feathered coelurosaurian Theropoda, theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous period (geology), Period. The name Drom ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

from the Djadokhta Formation of the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

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 ...

Discovery and naming

The holotype of ''Tsaagan'' was discovered in 1996 and first identified as a specimen of ''

Velociraptor ''Velociraptor'' (; ) is a genus of small dromaeosaurid dinosaurs that lived in Asia during the Late Cretaceous epoch, about 75 million to 71 million years ago. Two species are currently recognized, although others have been assigned in th ...

''. After a CAT-scan in May 1998 it was concluded that it represented a new genus. In December 2006 its

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

was named and described by Mark Norell, James Clark, Alan Turner, Peter Makovicky, Rinchen Barsbold and Timothy Rowe. The

species name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

, ''Tsaagan mangas'', should be read as a whole with the generic name qualifying the

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

, and is derived from the Mongolian words for "white monster" (), although with an accidental misspelling of the word Tsagaan. 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 ...

specimen, IGM 100/1015, was found near Xanadu in Ömnögovi Province in layers of the Djadokhta Formation dating to 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 ...

, 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 of ''Tsaagan'' and belonged to an adult individual.

Description

''Tsaagan'' was a medium-sized dromaeosaurid. In 2010

Gregory S. Paul Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology. He is best known for his work and research on theropoda, theropod dinosaurs and his detailed illustrations, both l ...

estimated its length at , its weight at . The skull in general appearance resembles that of ''Velociraptor'' 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 a jugal touching the squamosal.

Classification

''Tsaagan'' is a member of the group

Dromaeosauridae Dromaeosauridae () is a family of feathered coelurosaurian theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from ...

. A

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

analysis by Norell ''et al.'' originally indicated it was more precisely a member of the Velociraptorinae. In 2010 an analysis showed it was closely related to '' Linheraptor''; subsequently Senter (2011) and Turner, Makovicky and Norell (2012) argued that ''Linheraptor exquisitus'' is in fact a junior synonym of ''Tsaagan mangas''. Xu, Pittman ''et al''. (2015) reject this synonymy by responding to the counterarguments proposed using new and existing details of ''Linheraptors anatomy. Below are the results for the Eudromaeosauria

phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...

based on the

phylogenetic analysis In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

performed by Currie and Evans in 2019:

Paleoenvironment

''Tsaagan'' represents the only dromaeosaurid remains (other than isolated teeth) known from the Ukhaa Tolgod region, though another dromaeosaurid, ''Velociraptor'', is known from the same Djadokhta Formation. Animals that may have shared the same habitat with ''Tsaagan'' include ''

Protoceratops ''Protoceratops'' (; ) is a genus of small protoceratopsid dinosaurs that lived in Asia during the Late Cretaceous, around 75 to 71 million years ago. The genus ''Protoceratops'' includes two species: ''P. andrewsi'' and the larger ''P. hellenik ...

'', '' Shuvuuia'', the small

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

'' Zalambdalestes'', the multituberculate mammal '' Kryptobaatar'', as well as several lizards and two yet-undescribed species of troodontid and dromaeosaurid.

References

{{Taxonbar, from=Q133110 Eudromaeosauria Dinosaur genera Campanian dinosaurs Djadochta Formation Taxa named by Rinchen Barsbold Taxa named by Mark Norell Taxa named by James M. Clark Taxa named by Timothy B. Rowe Fossil taxa described in 2006 Dinosaurs of Mongolia

Discovery and naming

Description

Classification

Paleoenvironment

See also

References