What is true of the fossil record of mammalian origins?
A) It is a good example of punctuated equilibrium.
B) It shows that mammals and birds evolved from the same kind of dinosaur.
C) It includes transitional forms with progressively specialized teeth.
D) It indicates that mammals and dinosaurs did not overlap in geologic time.
E) It includes a series that shows the gradual change of scales into fur.

Question

Quizplus · Accepted Answer

The fossil record of mammalian origins includes transitional forms with progressively specialized teeth, such as the synapsids that evolved differentiated molars, and the early mammals that evolved specialized incisors, canines, and molars.

Answer: D
 The fossil record of mammalian origins indicates that mammals and dinosaurs did not overlap in geologic time, as the first mammals evolved after the extinction of dinosaurs at the end of the Cretaceous period.

Answer: A, B, E
 None of the choices A, B, or E are true of the fossil record of mammalian origins. Choice A, regarding punctuated equilibrium, may apply to some lineages of organisms, but not necessarily to mammalian evolution. Choice B, regarding the common origin of birds and mammals, is not supported by the fossil record, as birds evolved from a different group of dinosaurs (theropods) than the ancestors of mammals (synapsids). Choice E, regarding the evolution of fur from scales, is not supported by the fossil record, as there is no direct evidence of intermediate stages between reptilian scales and mammalian hair.

What Is True of the Fossil Record of Mammalian Origins