''Cionodon'' (meaning 'column tooth') is a dubious
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
hadrosaurid[J. R. Horner, D. B. Weishampel, and C. A. Forster. 2004. Hadrosauridae. In D. B. Weishampel, H. Osmolska, and P. Dodson (eds.), '']The Dinosauria
''The Dinosauria'' is an extensive book on dinosaurs, compiled by David B. Weishampel, Peter Dodson, and Halszka Osmólska. It has been published in 2 editions, with the first edition published in 1990, consisting of material from 23 scientists.B ...
'' (2nd edition). ''University of California Press, Berkeley'' 438-463 dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
from the
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger 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 ''creta'', ...
. The
type species
In 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 species that contains the biological type specimen ...
, ''C. arctatus'', was found in the
Denver Formation
The Denver Formation is a geological formation that is present within the central part of the Denver Basin that underlies the Denver, Colorado, area. It ranges in age from latest Cretaceous (Maastrichtian) to early Paleocene, and includes sediment ...
of
Lodge Pole Creek,
Colorado
Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...
and was formally described by
Edward Drinker Cope in 1874 based on the
holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
AMNH
The American Museum of Natural History (abbreviated as AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. In Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 26 i ...
3951, collected in 1873. It is a ''
nomen dubium'' because it is based on very fragmentary remains. Two other species have since been described: ''Cionodon kysylkumensis'' (
Riabinin, 1931), based on the holotype CCMGE 1/3760 (a set of
vertebra
The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...
e) from
Uzbekistan
Uzbekistan (, ; uz, Ozbekiston, italic=yes / , ; russian: Узбекистан), officially the Republic of Uzbekistan ( uz, Ozbekiston Respublikasi, italic=yes / ; russian: Республика Узбекистан), is a doubly landlocked cou ...
,
[A. N. Riabinin. 1931. Ostatki dinozavrov iz verkhnego mela nizov'ev r. Amu-Dar'i Amu-Daria_River.html" ;"title="Amu_Darya.html" ;"title="n the dinosaurian remains from the Upper Cretaceous of the lower parts of the Amu Darya">Amu-Daria River">Amu_Darya.html" ;"title="n the dinosaurian remains from the Upper Cretaceous of the lower parts of the Amu Darya">Amu-Daria River ''Zapiski Rossiyskogo Mineralogicheskogo Obshchestva'' 60(1):114-118] and ''Cionodon stenopsis'' (Cope, 1875), discovered in rocks from the Judith River Formation of Alberta, Canada, Alberta, Canada in 1874.
[ E. D. Cope. 1875. On the transition beds of the Saskatchewan district. ''Proceedings of the Academy of Natural Sciences of Philadelphia'' 27:2-3] Although both are probably hadrosaurs,
they are known only from fragmentary remains and ''Cionodon kysylkumensis'' has since been reclassified as ''
Bactrosaurus kysylkumensis''.
See also
*
Timeline of hadrosaur research
A timeline is a display of a list of events in chronological order. It is typically a graphic design showing a long bar labelled with dates paralleling it, and usually contemporaneous events.
Timelines can use any suitable scale represent ...
References
Late Cretaceous dinosaurs of North America
Hadrosaurs
Nomina dubia
Fossil taxa described in 1874
Taxa named by Edward Drinker Cope
Paleontology in Colorado
Maastrichtian genus first appearances
Maastrichtian genus extinctions
Ornithischian genera
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