The common ancestors of birds and mammals were very early (stem) reptiles, which almost certainly possessed three-chambered hearts (two atria, one ventricle). Birds and mammals, however, are alike in having four-chambered hearts (two atria, two ventricles). The fourchambered hearts of birds and mammals are best described as ________.

TLS Online TPP Program

#Question id: 8919

#Section 2: Evolution

The last common ancestor of all animals was probably a

TLS Online TPP Program

#Question id: 8920

#Section 2: Evolution

Almost all of the major animal body plans seen today appeared in the fossil record over 500 million years ago at the beginning of the

TLS Online TPP Program

#Question id: 8921

#Section 2: Evolution

Evidence of which structure or characteristic would be most surprising to find among fossils of the Ediacaran fauna?

TLS Online TPP Program

#Question id: 8922

#Section 2: Evolution

Which statement is most consistent with the hypothesis that the Cambrian explosion was caused by the rise of predator-prey relationships?

TLS Online TPP Program

#Question id: 8923

#Section 2: Evolution

Which of these genetic processes may be most helpful in accounting for the Cambrian explosion?

TLS Online TPP Program

#Question id: 8925

#Section 2: Evolution

What is the probable sequence in which the following clades of animals originated, from earliest to most recent?

1. tetrapods

2. vertebrates

3. deuterostomes

4. amniotes

5. bilaterians