Birds are thought to have evolved from small feathered dinosaurs. Evidence for this comes from the fossil discoveries of , a transitional form between dinosaurs and birds.

Archaeopteryx

Explanation: The Archaeopteryx is known as the transitional form between dinosaurs and birds. Archaeopteryx had features that links it to present-day reptiles and birds. It had feathered wings but a bony tail, and is believed to have evolved into birds in 10 million years.  

The Archaeopteryx had a flat sternum, unlike modern day birds. Birds which fly have a keeled sternum and it is possible that the Archaeopteryx did not use sustained flight as a method of movement and the feathers were mostly a means of insulation.  

i disagree that there is little difference between adult female development and adult male development. sociological studies comparing female and male pathways to adulthood, revelead that there are sustancial differences between them. particularly, female and male differ from timing of marriage, when they began to live with children and the likelihood of combining wife/husband and parent roles.