How to differentiate between Reptile fossil and Mammal fossil?

Here is the differences:

1. the lower jaw is comprised of several different bones.

2. The classic reptilian skull also has a small hole, or “third eye”.

3.

1. In mammals, however, the lower jaw is comprised of only one bone – the dentary

2. It has no hole in skull.

one would be wind another would be water density

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides