All birds living today are descended from a group of

Last updated: 6/9/2023

All birds living today are descended from a group of dinosaurs called theropods Theropods first appeared in the fossil record around 200 million years ago However fos sils of taxa similar to modern birds can be found in the fossil record from around 66 million years ago The table below provides information about certain traits in theropods and modern birds An X indicates the presence of a trait Trait A Bipedal B Hollow Bones C Feathers Jaws with Sharp Teeth Long Boney Tail Fused Clavicle Reversed First Toe Theropods X X A table that shows the comparison of traits in theropods and modern birds X X Modern Birds X X Each of the answer choices below describes a specific fossil Which fossil provides the strongest evidence for the discovery of a transitional species that existed in the period between theropods and modern birds X X X The fossil of an organism with a reversed first toe and a long bony tail was found in a 145 million year old rock layer The fossil of an organism with feathers and a reversed front toe was found in a 55 mil The fossil of a bipedal organism with hollow bones was found in a 100 million year old rock layer