In $1938$,a fish caught in .......... was thought to be extinct,but it was a Coelacanth.

$A$: Blood group analysis shows that human beings are more closely related to apes than to monkeys.
$R$: The blood groups $A$ and $B$ are found in apes but not in monkeys.

Explain evolution based on comparative anatomy and morphology.

Basic principles of embryonic development were stated by

The Biogenetic Law was proposed by:

In evolution,studies can be conducted at the molecular level. For example,proteins found in the blood of humans and apes are similar. The base sequences in nucleic acids and amino acid sequences in proteins are similar in related organisms. What do all these examples specifically refer to?