How does embryology help scientists reconstruct evolutionary lines?
1) We can determine how long embryological development takes. The longer it takes for an embryo to develop, the more evolved it is.
2) We can differentiate between the embryos of placental and non-placental animals to understand how dinosaurs mated.
3) We can track how long embryos of different species look alike. The longer they look alike during development, the closer two species likely are evolutionarily.
4) We can see when different analogous structures appear.