section_path: Origin/Phylogeny
section_name: Phylogeny
paragraph_text: Phylogeny
  
  Water or ground-dwelling fowl similar to modern partridges, in the Galliformes, the order of bird that chickens belong to, survived the Cretaceous–Paleogene extinction event that killed all tree-dwelling birds and their dinosaur relatives. Chickens are descended primarily from the red junglefowl (Gallus gallus) and are scientifically classified as the same species. Domesticated chickens freely interbreed with populations of red junglefowl. The domestic chicken has subsequently hybridised with grey junglefowl, Sri Lankan junglefowl and green junglefowl; a gene for yellow skin, for instance, was incorporated into domestic birds from the grey junglefowl (G. sonneratii). It is estimated that chickens share between 71 and 79% of their genome with red junglefowl.