Euornithes (jan 31, 130000000 BC – dec 31, 0)
Description:
Clarke et al. (2006) found that the most primitive known euornithians (the Yanornithiformes) had a mosaic of advanced and primitive features. These species retained primitive features like gastralia (belly ribs) and a pubic symphysis. They also showed the first fully modern pygostyles, and the type specimen of Yixianornis (IVPP 13631) preserves eight elongated rectrices (tail feathers) in a modern arrangement. No earlier pygostylians are known which preserve a fan of tail feathers of this sort; instead, they show only paired plumes or a tuft of short feathers.Added to timeline:
Date:
jan 31, 130000000 BC
dec 31, 0
~ 5883516 years