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An arctometatarsalian organism is one in which the
''Functional morphology of the tyrannosaurid arctometatarsus''
University of Calgary.
An arctometatarsalian organism is one in which the proximal
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
part of the middle 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 med ...
is pinched between the surrounding 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 med ...
s. The trait appears to be highly homoplastic
Homoplasy, in biology and phylogenetics, is the term used to describe a Phenotypic trait, feature that has been gained or lost independently in separate lineages over the course of evolution. This is different from Homology (biology), homology, wh ...
, common in certain sorts of 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 ...
s accustomed to running (among them the tyrannosauroids, ornithomimosaurs
Ornithomimosauria ("bird-mimic lizards") are theropod dinosaurs which bore a superficial resemblance to the modern-day ostrich. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period of Laurasia (now Asia, Europe and North ...
, and troodontids
Troodontidae is a clade of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil discov ...
), to evenly transmit force to the 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 med ...
s.Snively, E. (2000)''Functional morphology of the tyrannosaurid arctometatarsus''
University of Calgary.
References
Evolutionary biology concepts Vertebrate anatomy Skeletal system Dinosaur anatomy {{dinosaur-stub