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Tyrannosaurus foot showing the compressed arctometatarsalian condition of the middle metatarsal, compared to that of Allosaurus

An arctometatarsalian organism is one in which the proximal part of the middle metatarsal is pinched between the surrounding metatarsals. The trait appears to be highly homoplastic, common in certain sorts of dinosaurs accustomed to running (among them the tyrannosauroids, ornithomimosaurs, and troodontids), to evenly transmit force to the metatarsals.[1][2]


  1. ^ "Evolutionary morphology of the coelurosaurian arctometatarsus: descriptive, morphometric and phylogenetic approaches" (PDF). Archived from the original (PDF) on 2011-07-06. Retrieved 2009-10-24.
  2. ^ Snively, E. (2000). Functional morphology of the tyrannosaurid arctometatarsus Archived 2016-07-23 at the Wayback Machine. University of Calgary.