First a disclamer - No one except the devs (and i highly suspect even most of them don't really know any more) knows definitely 100% how it works. Some of the numbers/formulas are just by observation.
The stats on a dino are determined by a base value in each stat and level-up points which add a certain amount of values. Dino-Levels are the sum of those level-ups plus one. Lets look at a Rex for example.
A level 1 Rex has the following stats:
Health 1100.1
Stamina 420
Oxygen 150