What is true of the fossil record of mammalian origins? what is true of the fossil record of mammalian origins? it includes a series that shows the gradual change of scales into fur. it shows that mammals and birds evolved from the same kind of dinosaur. it indicates that mammals and dinosaurs did not overlap in geologic time. it includes transitional forms with progressively specialized teeth?

It includes transitional forms with progressively specialized teeth.  
The key thing to remember about fossils is: If it's not hard, it's rarely preserved. Now let's look at the options and pick the correct one that matches the known facts.  
It includes a series that shows the gradual change of scales into fur.
 * This option is rather hard to swallow. There have been a few fossils discovered with soft tissue features, but those fossils are extremely rare. Expecting a record of a gradual change of soft tissues is not likely. So this is a bad choice. 
 It shows that mammals and birds evolved from the same kind of dinosaur.
 * The evidence shows that mammals evolved at the end of the Triassic period from therapsids (about 201 to 250 million years ago). Birds are a relative newcomer with Archaeopteryx being approximately 150 million years ago. So this choice is wrong. 
 It indicates that mammals and dinosaurs did not overlap in geologic time.
 * Nope. Mammals existed throughout the Jurassic period that came after the Triassic period where the first mammals were discovered. So this is a bad choice. 
 It includes transitional forms with progressively specialized teeth.
 * Most definitely. Teeth are nice hard structures that are easily fossilized. And this is the correct choice.