Branch of zoology dealing with similarities and differences between individuals related by descent is

$A$ : Lycaenops is a connecting link between reptiles and mammals.
$R$ : In permian period there was origin of mammal like reptiles.

Flippers of Penguins and Dolphins are examples of:

Assertion : The earliest fossil form in the phylogeny of horse is eohippus.

Reason : Eohippus lived during the early pliocene epoch.