''Tanycolagreus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

coelurosauria Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, t ...

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

from the

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

Discovery and naming

Tanycolagreus topwilsoni skull cast - Natural History Museum of Utah - DSC07224

In 1995 Western Paleontological Laboratories, Inc. uncovered the partial skeleton of a small theropod at the

Bone Cabin Quarry Bone Cabin Quarry is a dinosaur quarry that lay approximately northwest of Laramie, Wyoming near historic Como Bluff. During the summer of 1897 Walter Granger, a paleontologist from the American Museum of Natural History, came upon a hillside li ...

West locality,

Albany County, Wyoming Albany County ( ) is a county in the U.S. state of Wyoming. As of the 2020 United States Census, the population was 37,066. Its county seat is Laramie, the site of the University of Wyoming. Its south border lies on the northern Colorado state ...

, from the Salt Wash Member of the

Morrison Formation The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltston ...

, dating to the Oxfordian-

Tithonian In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma (million years ago). It is preceded by ...

. At first the find was considered to be a specimen of '' Coelurus'' but subsequent study indicated it represented a species new to science, that in 2001 was announced to be named ''Tanycolagreus topwilsoni''. It was actually named and described by

Kenneth Carpenter Kenneth Carpenter (born September 21, 1949, in Tokyo, Japan) is a paleontologist. He is the former director of the USU Eastern Prehistoric Museum and author or co-author of books on dinosaurs and Mesozoic life. His main research interests ...

, Clifford Miles and

Karen Cloward Karen may refer to: * Karen (name), a given name and surname * Karen (slang), a term and meme for a demanding woman displaying certain behaviors People * Karen people, an ethnic group in Myanmar and Thailand ** Karen languages or Karenic ...

in 2005. The

etymology Etymology () The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the form of words ...

of the generic name ''Tanycolagreus'', suggested by Ben Creisler, is based upon the greater length of its forelimbs and hindlimbs compared to ''Coelurus''. It is derived from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

prefix A prefix is an affix which is placed before the stem of a word. Adding it to the beginning of one word changes it into another word. For example, when the prefix ''un-'' is added to the word ''happy'', it creates the word ''unhappy''. Particul ...

τανυ~, ''tany''~: 'long, stretched out', κῶλον, ''kolon'': 'limb' and ἀγρεύς, ''agreus'': 'hunter'. The specific name honors George Eugene "Top" Wilson, the father of a benefactor financially supporting the scientific research.Carpenter, K., Miles, C., and Cloward, K. (2005). "New small theropod from the Upper Jurassic Morrison Formation of Wyoming." in Carpenter, K. 2005. ''The Carnivorous Dinosaurs'', Indiana University Press: 23-48 Tanycolagreus topwilsoni slab

The fossil,

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 seve ...

TPII 2000-09-29, was donated to science by an anonymous benefactor. It is part of the collection of

Thanksgiving Point Thanksgiving Point is a 501(c)(3) nonprofit indoor and outdoor farm, garden, and museum complex in Lehi, Utah, United States. Its five main attractions include Ashton Gardens, Butterfly Biosphere, Farm Country, Museum of Ancient Life, and Museum ...

Institute, Inc. and displayed in the North American Museum of Ancient Life at

Lehi, Utah Lehi ( ) is a city in Utah County, Utah, United States. It is named after Lehi, a prophet in the Book of Mormon. The population was 75,907 at the 2020 census, up from 47,407 in 2010. The rapid growth in Lehi is due, in part, to the rapid develo ...

. It includes an incomplete skull and

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

(lower jaws) and much of the

postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...

l skeleton, i.e. the parts behind the head. The skull of ''Tanycolagreus'' is less well known than its postcranial

anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having i ...

, and only the following elements have been found: left

nasal Nasal is an adjective referring to the nose, part of human or animal anatomy. It may also be shorthand for the following uses in combination: * With reference to the human nose: ** Nasal administration, a method of pharmaceutical drug delivery * ...

, left lacrimal, left

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

and one premaxillary tooth, left

postorbital The ''postorbital'' is one of the bones in vertebrate skulls which forms a portion of the dermal skull roof and, sometimes, a ring about the orbit. Generally, it is located behind the postfrontal and posteriorly to the orbital fenestra. In some ...

, left

quadratojugal The quadratojugal is a skull bone present in many vertebrates, including some living reptiles and amphibians. Anatomy and function In animals with a quadratojugal bone, it is typically found connected to the jugal (cheek) bone from the front and ...

, incomplete left

squamosal The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral co ...

, right quadrate, right

splenial The splenial is a small bone in the lower jaw of reptiles, amphibians and birds, usually located on the lingual side (closest to the tongue) between the angular and surangular The suprangular or surangular is a jaw bone found in most land ver ...

, left articular, and two cheek teeth. A

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). O ...

has been assigned to the species: specimen AMNH 587 consisting of an incomplete hand also collected from Bone Cabin Quarry and originally in 1903 by

Henry Fairfield Osborn Henry Fairfield Osborn, Sr. (August 8, 1857 – November 6, 1935) was an American paleontologist, geologist and eugenics advocate. He was the president of the American Museum of Natural History for 25 years and a cofounder of the American Euge ...

referred to '' Ornitholestes hermanni''. Two other fossils have been referred to ''Tanycolagreus'': UUVP 2999, a

, originally in 1974 referred to ''

Stokesosaurus ''Stokesosaurus'' (meaning "Stokes' lizard") is a genus of small (around in length), carnivorous early tyrannosauroid theropod dinosaurs from the late Jurassic period of Utah, United States. History From 1960 onwards Utah geologist William ...

clevelandi'', from the Cleveland-Lloyd Quarry of

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

; and USNM 5737, a pair of distal pubes from

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 the ...

earlier in 1920 by

Charles Whitney Gilmore Charles Whitney Gilmore (March 11, 1874 – September 27, 1945) was an American paleontologist who gained renown in the early 20th century for his work on vertebrate fossils during his career at the United States National Museum (now the N ...

referred to ''Coelurus''. These specimens are from the later

Brushy Basin Member The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone, ...

. ''Tanycolagreus'' is present in stratigraphic zone 2 of the Morrison. Remains possibly referrable to ''Stokesosaurus'' have been recovered from stratigraphic zone 5 of the Morrison Formation.Foster, J. (2007). "Appendix." ''Jurassic West: The Dinosaurs of the Morrison Formation and Their World''. Indiana University Press. pp. 327-329 A life restoration of ''Tanycolagreus'' is also on display at the North American Museum of Ancient Life, where it is portrayed as preying upon a small

ornithischia Ornithischia () is an extinct order of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name ''Ornithischia'', or "bird-hipped", reflects this similarity and is derived from the Greek ...

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 ...

, ''

Nanosaurus ''Nanosaurus'' ("small or dwarf lizard") is the name given to a genus of neornithischian dinosaur that lived about 155 to 148 million years ago, during the Late Jurassic-age. Its fossils are known from the Morrison Formation of the south-weste ...

agilis''.

Description

Carpenter ''et al.'' (2005, pp. 43–44) determined that the holotype of ''Tanycolagreus'' represents a subadult individual which measured approximately long in life. However, one of the referred fossils, the premaxilla from the Cleveland-Lloyd Quarry, would have belonged to a larger individual, measuring long. In 2010 Gregory S. Paul estimated the weight of a four-meter-long animal at .Paul, G.S., 2010, ''The Princeton Field Guide to Dinosaurs'', Princeton University Press p. 124 It cannot be determined whether or not the Cleveland-Lloyd specimen represents a fully mature adult, so the upper size limit for the

taxon In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...

remains unknown. The head of ''Tanycolagreus'' is large, elongated and rectangular in profile due to a blunt snout. The leg is rather long and lightly built. Tanycolagreus size

Carpenter ''et al.'' (2005; pp. 27 & 29) diagnosed ''Tanycolagreus topwilsoni'' as follows: "Medium-sized

tetanuran Tetanurae (/ˌtɛtəˈnjuːriː/ or "stiff tails") is a clade that includes most theropod dinosaurs, including megalosauroids, allosauroids, tyrannosauroids, ornithomimosaurs, compsognathids and maniraptorans (including birds). Tetanurans ar ...

having short, deep-bodied premaxilla pierced by narial foramen at base of nasal process, orbital process on postorbital, T-shaped quadratojugal, centrodiapophyseal lamina on dorsals. Differs from ''Coelurus'' in the absence of pleurocoel on anterior dorsals; posterior caudal prezygapophyses elongated to one-third centrum length, rather than short; straight, rather than sigmoidal, humeral shaft; bowed, rather than straight, radius; flat-bottomed rather than arced pubic foot; straight rather than sigmoidal femoral shaft;

metatarsal The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the me ...

length

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