Answer:
Common ancestor is the main factor that determines that all terrestrial animals are quadrupedal.
Step-by-step explanation:
- Phylogeny means the evolution of the organisms or genetically related organism and how they are related.
- The study of phylogeny is called as phylogenetics. Terrestrial means those who live on land.
- Mammals are one who gives birth to their offspring directly. They are generally warm-blooded, breath air.
- Studying each state of the ancestor and also tracing the organism characteristics during evolution.