Main Page | See live article | Alphabetical index An arctometatarsalian organism is one in which the proximal part of the third metatarsal is pinched between metatarsals II and IV. The trait appears to be highly homoplastic, common in certain sorts of dinosaurs accustomed to running (among them the tyrannosaurids), to evenly transmit force to the metatarsals. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.