Tarsometatarsus

 The tarsometatarsus is a bone that is just found in the lower leg of birds and some non-avian dinosaurs. It is framed from the combination of a few bones found in different sorts of creatures, and homologous to the mammalian bone structure (lower leg bones) and metatarsal bones (foot). Despite this, the tarsometatarsus of birds is regularly alluded to as the knife, bone structure or metatarsus. 

Tarsometatarsal combination happened severally and degrees all through bird development. In particular, in Neornithes (present-day birds), albeit the bones are joined along their whole length, the combination is generally intensive at the distal (metatarsal) end. In the Enantiornithes, a gathering of Mesozoic avialans, the combination was finished at the proximal (tarsal) end, however, the distal metatarsi were still somewhat particular. 

While these intertwined bones are most popular by birds and their family members, avians are neither the solitary gathering nor the first to have tarsometatarsi. In a noteworthy instance of equal advancement, they were likewise present in the Heterodontosauridae, a gathering of small ornithischian dinosaurs very disconnected from birds. The most established remaining parts of this taxon date from the Late Triassic above 200 million years prior, and originate before the main birds with tarsometatarsi by almost 100 million years.