''Albertadromeus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

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 ...

orodromine Thescelosauridae is a clade of neornithischians from the Cretaceous of East Asia and North America. The group was originally used as a name by Charles M. Sternberg in 1937, but was not formally defined until 2013, where it was used by Brown and ...

thescelosaurid

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 ...

known from the upper part 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 ...

Oldman Formation The Oldman Formation is a stratigraphic unit of Late Cretaceous (Campanian stage) age that underlies much of southern Alberta, Canada. It consists primarily of sandstones that were deposited in fluvial channel and floodplain environments. It was ...

(middle

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 ...

stage) of

Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...

, Canada. It contains a single species, ''Albertadromeus syntarsus''.

Etymology

The composite term ''Albertadromeus'' is derived from the name of the Canadian province "Alberta", and the

Greek Greek may refer to: 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 of all kno ...

word ''dromeus'' (δρομεύς) meaning "runner", a reference to its inferred cursorial nature; thus "runner from Alberta". 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 ...

, ''syntarsus'' is derived from Greek words "syn" (συν) meaning "together" and "tarsus" (ταρσός) meaning "ankle", hence "together-ankle" a reference to the condition where its distal fibula is fused to its distal tibia. This dinosaur was described and named by Caleb Marshall Brown, David C. Evans, Michael J. Ryan & Anthony P. Russell in

2013 2013 was the first year since 1987 to contain four unique digits (a span of 26 years). 2013 was designated as: *International Year of Water Cooperation *International Year of Quinoa Events January * January 5 – 2013 Craig, Alask ...

and the

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 ...

is ''Albertadromeus syntarsus''.

Description

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 of ''Albertadromeus'' TMP 2009.037.0044 consists of two dorsal vertebrae, a caudal vertebra, cervical ribs, ossified tendons, the left

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

and

fibula The fibula (: fibulae or fibulas) or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. ...

, an incomplete right fibula, and a fragmentary

metatarsal The metatarsal bones or metatarsus (: metatarsi) are a group of five long bones in the midfoot, located between the tarsal bones (which form the heel and the ankle) and the phalanges ( toes). Lacking individual names, the metatarsal bones are ...

and

ungual An ungual (from Latin ''unguis'', i.e. ''nail'') is a highly modified distal toe bone which ends in a hoof, claw, or nail. Elephants and ungulates have ungual phalanges, as did the sauropod Sauropoda (), whose members are known as sauropods (; ...

. The skull is unknown in this genus. The authors note that despite the few bones recovered, their moderate quality of preservation nonetheless provides enough morphological detail to allow for diagnosis on the species level. Its elongate tibia has been strongly correlated with cursorial habits. The tibia of ''Albertadromeus'' is slightly more elongate than that of ''

Orodromeus ''Orodromeus'' (meaning "Mountain Runner") is a genus of herbivorous orodromine thescelosaurid dinosaur from the Late Cretaceous of North America. Only one species is known, the type species ''Orodromeus makelai''. Discovery and naming The re ...

'', and significantly more elongate than that of ''

Parksosaurus ''Parksosaurus'' (meaning "William Parks (paleontologist), William Parks's lizard") is a genus of neornithischian dinosaur from the Maastrichtian, early Maastrichtian-age Upper Cretaceous Horseshoe Canyon Formation of Alberta, Canada. It is based ...

'' (ROM 804), ''

Thescelosaurus ''Thescelosaurus'' ( ) is a genus of Ornithischia, ornithischian dinosaur that lived during the Late Cretaceous period (geology), period in western North America. It was named and described in 1913 by the Paleontology, paleontologist Charles W. G ...

'' (USNM 7757 and RSM P 1225.1), ''

Hypsilophodon ''Hypsilophodon'' (; meaning "high-crested tooth") is a neornithischian dinosaur genus from the Early Cretaceous period of England. It has traditionally been considered an early member of the group Ornithopoda, but recent research has put this ...

'' (NMHUK R5830), ''

Dryosaurus ''Dryosaurus'' ( , meaning 'tree lizard', Greek ' () meaning 'tree, oak' and () meaning 'lizard', (the name reflects the forested habitat, not a vague oak-leaf shape of its cheek teeth as is sometimes assumed) is a genus of an ornithopod dinos ...

'' (YPM 1876), and ''

Stegoceras ''Stegoceras'' is a genus of Pachycephalosauria, pachycephalosaurid (dome-headed) dinosaur that lived in what is now North America during the Late Cretaceous Period (geology), period, about 77.5 to 74 million years ago (mya). The first specim ...

'' (UALVP 002). ''Albertadromeus'' was a small-bodied, bipedal, cursorially adapted (built to run) neornithischian.

Diagnosis

According to Brown et al. (2013) ''Albertadromeus'' can be distinguished based on the following characteristics: * The distal fibula is reduced to a thin sheet of bone that is fused to the anterior surface of tibia for the distal one-third of its length (shared with heterodontosaurids) * The lateral condyle of proximal tibia is strongly bilobed (shared with ''Changchunsaurus'', ''Eocursor'', ''Hypsilophodon'', ''Jeholosaurus'', ''Lesothosaurus'', ''Orodromeus'', ''Oryctodromeus'') * A prominent

cnemial crest The cnemial crest is a crestlike prominence located at the front side of the head of the tibiotarsus or tibia in the legs of many mammals and reptiles (including birds and other dinosaurs). The main extensor muscle of the thigh In anatomy, the ...

that projects dorsally (and anterolaterally), resulting in a posterior sloped dorsal extremity of the tibia (also present in ''Gasparinisaura'' and ''Micropachycephalosaurus'').

Classification

Brown et al. (2013) erected a new taxon ''Orodrominae'' to differentiate those species that are more closely related to ''

'' from those more closely related to ''

''. The validity of this new taxon is supported by the following: (a) the

foramen In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, artery, ...

magnum is between 20% and 30% of the width of the

occipital condyle The occipital condyles are undersurface protuberances of the occipital bone in vertebrates, which function in articulation with the superior facets of the Atlas (anatomy), atlas vertebra. The condyles are oval or reniform (kidney-shaped) in shape ...

; (b) the pubis is articulated with a sacral rib; (c) there is a sharp and pronounced scapular spine; and (d) the fibular shaft is D-shaped in cross-section. The new taxon ''Orodrominae'' includes the newly discovered dinosaur ''Albertadromeus'', ''

Zephyrosaurus ''Zephyrosaurus'' (meaning "westward wind lizard") is a genus of orodromine ornithischian dinosaur. It is based on a partial skull and postcranial fragments discovered in the Aptian-Albian-age Lower Cretaceous Cloverly Formation of Carbon Cou ...

'', ''Orodromeus'' and '' Oryctodromeus''. Phylogenetic analyses suggest that ''Albertadromeus'' forms a clade with ''Zephyrosaurus'' and ''Orodromeus'', with ''Oryctodromeus'' being less closely related. The following is a

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

based on the phylogenetic analysis conducted by Brown et al. in 2013, showing the relationships of ''Albertadromeus'':

Paleoecology

The remains of the type specimen of ''Albertadromeus'' was recovered in the Canal Creek locality in the Upper

, which is part of the

Belly River Group The Belly River Group is a stratigraphic unit of Late Cretaceous age in the Western Canadian Sedimentary Basin. It takes the name from the Belly River, a tributary of the Oldman River in southern Alberta, and was first described in outcrop on t ...

Alberta, Canada Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...

. The specimen was collected in a two-meter-thick fine to very fine sandstone unit that was deposited during the

stage of the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

period, approximately 77 to 76 million years ago. This specimen is housed in the collection of the

Royal Tyrrell Museum of Palaeontology The Royal Tyrrell Museum of Palaeontology (RTMP; often referred to as the Royal Tyrrell Museum) is a palaeontology museum and research facility in Drumheller, Alberta, Canada. The museum was named in honour of Joseph Burr Tyrrell, and is situate ...

Drumheller Drumheller is a town on the Red Deer River in the badlands of east-central Alberta, Canada. It is located northeast of Calgary and south of Stettler. The Drumheller portion of the Red Deer River valley, often referred to as Dinosaur Vall ...

. Studies suggest that the

paleoenvironment Paleoecology (also spelled palaeoecology) is the study of interactions between organisms and/or interactions between organisms and their environments across geologic timescales. As a discipline, paleoecology interacts with, depends on and informs ...

of the

was an ancient

coastal plain A coastal plain (also coastal plains, coastal lowland, coastal lowlands) is an area of flat, low-lying land adjacent to a sea coast. A fall line commonly marks the border between a coastal plain and an upland area. Formation Coastal plains can f ...

.Eberth, D.A., and Hamblin, A.P., 1993 , Tectonic, stratigraphic, and sedimentologic significance of a regional discontinuity in the upper Judith River Group (Belly River wedge) of southern Alberta, Saskatchewan, and northern Montana: Canadian Journal of Earth Sciences, 30, 174‒200. This formation has produced the remains of the theropods ''

Saurornitholestes ''Saurornitholestes'' ("lizard-bird thief") is a genus of carnivorous dromaeosaurid theropod dinosaur from the late Cretaceous of Canada (Alberta and Saskatchewan) and the United States (Montana, New Mexico, Alabama, and South Carolina). Two spe ...

'', ''

Daspletosaurus ''Daspletosaurus'' ( ; meaning "frightful lizard") is a genus of tyrannosaurid dinosaur that lived in Laramidia between about 77 and 74.4 million years ago, during the Late Cretaceous Period. The genus ''Daspletosaurus'' contains three named ...

'', ''

Troodon ''Troodon'' ( ; ''Troödon'' in older sources) is a controversial genus of relatively small, bird-like theropod dinosaurs definitively known from the Campanian age of the Late Cretaceous period (about 77 million years ago). It includes at l ...

'', and ''

Dromaeosaurus ''Dromaeosaurus'' (; ) is a genus of Dromaeosauridae, dromaeosaurid theropod dinosaur that lived during the Late Cretaceous period (middle late Campanian and Maastrichtian), sometime between 80 and 69 million years ago, in Alberta, Canada and th ...

'', the ceratopsids '' Albertaceratops'', ''

Chasmosaurus ''Chasmosaurus'' ( ) is a genus of ceratopsid dinosaur from the Late Cretaceous Period in North America. Its given name means 'opening lizard', referring to the large openings ( fenestrae) in its frill (Greek ''chasma'', meaning 'opening', 'hol ...

'', ''

Anchiceratops ''Anchiceratops'' ( ) is an extinct genus of chasmosaurinae, chasmosaurine ceratopsid dinosaur that lived approximately 72 to 71 million years ago during the latter part of the Cretaceous Period (geology), Period in what is now Alberta, Canada. ' ...

'', and ''

Coronosaurus ''Coronosaurus'' is a genus of centrosaurine ceratopsian dinosaurs which lived in the Late Cretaceous, in the middle Campanian stage. Its remains, two bone beds, were discovered by Phillip J. Currie in the Oldman Formation of Alberta, Canada, ...

'', the hadrosaurids ''

Brachylophosaurus ''Brachylophosaurus'' ( or ) is a genus of hadrosaurid dinosaur that lived during the Late Cretaceous period of western North America. It was first named in 1953 by Charles Mortram Sternberg for a skull and skeleton he discovered in 1936 in th ...

'', ''

Gryposaurus ''Gryposaurus'' (meaning "hooked-nosed (Ancient Greek, Greek ''grypos'') lizard"; sometimes incorrectly translated as "griffin (Latin ''gryphus'') lizard") was a genus of hadrosaur, duckbilled dinosaur that lived about 80 to 75 million years ag ...

'', ''

Parasaurolophus ''Parasaurolophus'' (; meaning "beside crested lizard" in reference to ''Saurolophus'') is a genus of hadrosaurid "duck-billed" dinosaur that lived in what is now western North America and possibly Asia during the Late Cretaceous period, a ...

'', ''

Maiasaura ''Maiasaura'' (from the Greek ''μαῖα'', meaning "midwife" and ''σαύρα'', the feminine form of ''saurus'', meaning "reptile") is a large herbivorous saurolophine hadrosaurid ("duck-billed") dinosaur genus that lived in the area currently ...

'', and ''

Corythosaurus ''Corythosaurus'' (; ) is a genus of hadrosaurid "duck-billed" dinosaur from the Late Cretaceous Period (geology), period, about 77–75.7 million years ago, in what is now Laramidia, western North America. Its name is derived from the Anci ...

'', as well as other dinosaurs that shared that their paleoenvironment with ''Albertadromeus''.

References

{{Taxonbar, from=Q12973101 Thescelosauridae Dinosaur genera Campanian dinosaurs Oldman Formation Dinosaurs of Canada Fossil taxa described in 2013