''Tatankacephalus'' is a basal

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 n ...

nodosaurid Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous period in what is now North America, South America, Europe, and Asia. Description Nodosaurids, like their close relatives the ankylosaurids, w ...

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 ...

that lived during the

Early Cretaceous The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pr ...

. Its length has been estimated at 7 meters (23 ft). Its

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

has been collected from the

Cloverly Formation The Cloverly Formation is a geological formation of Early and Late Cretaceous age (Valanginian to Cenomanian stage) that is present in parts of Montana, Wyoming, Colorado and Utah in the western United States. It was named for a post office on ...

(

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ag ...

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± ...

) of central

Montana Montana () is a U.S. state, state in the Mountain states, Mountain West List of regions of the United States#Census Bureau-designated regions and divisions, division of the Western United States. It is bordered by Idaho to the west, North ...

, USA, during 1996, 1997 and 1998, in the region of the

Middle Dome Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (disambiguation) * Middle Brook (disambiguation) * Middle Creek ( ...

in Wheatland County. 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( ...

is ''T. cooneyorum'', described by William L. Parsons and

Kirsten Parsons Kirsten is both a given name and a surname. Given name Kirsten is a female given name. It is a Scandinavian form of the names Christina and Christine.Oglala The Oglala (pronounced , meaning "to scatter one's own" in Lakota language) are one of the seven subtribes of the Lakota people who, along with the Dakota, make up the Očhéthi Šakówiŋ (Seven Council Fires). A majority of the Oglala live ...

''tatanka'', "

bison Bison are large bovines in the genus ''Bison'' (Greek: "wild ox" (bison)) within the tribe Bovini. Two extant and numerous extinct species are recognised. Of the two surviving species, the American bison, ''B. bison'', found only in North ...

" and Greek ''kephale'', "head", in reference to the rounded head form. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

honours the family of John Patrick Cooney. 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 seve ...

is MOR 1073, a partial skull with an estimated total undamaged length of 32 centimetres, lacking the lower jaws. Also some ribs,

osteoderm Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinc ...

s and a tooth have been recovered. The front of the snout is missing. The specimen is that of an adult individual. According to the authors the fossil has not been deformed by compression, allowing to distinguish it from ''

Sauropelta ''Sauropelta'' ( ; meaning 'lizard shield') is a genus of nodosaurid dinosaur that existed in the Early Cretaceous Period of North America. One species (''S. edwardsorum'') has been named although others may have existed. Anatomically, ''Saurope ...

edwardsorum'', another akylosaurian found in the same formation. The head is domed and the eye-sockets are round. A large bone ridge runs transversely across the back of the head. The fossil skull itself no longer had any teeth in it but a single tooth was found, lacking the cingulum. Two osteoderms were found; one was intact. It has a length of 137 and a width of 115 millimetres. It is hollow and conical. A

cladistic Cladistics (; ) 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 typically shared derived ch ...

analysis found that ''Tatankacephalus'' was a basal member of the Ankylosauridae and relatively closely related to '' Gastonia''. Basal traits include the retention of premaxillary teeth in the front of the upper jaws and a skull opening, the lateral temporal fenestra, that was not covered by the skull armour. A new

cladistic analysis Cladistics (; ) 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 typically shared derived ch ...

performed by Thompson ''et al.'', 2011 suggests that ''Tatankacephalus'' is a

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

References

{{Taxonbar, from=Q568412 Nodosaurids Early Cretaceous dinosaurs of North America Fossil taxa described in 2009 Paleontology in Montana Ornithischian genera

See also

References