<span>Certainly. Every organism has a variety of different characteristics. One person writing a key might choose to use different characteristics than another person would use.
For example: Here's a key for separating fish, snake, frog and mouse
1.
A. Has scales on its skin ... 2
B. Has no scales on its skin ... 3
2.
A. Breathes with gills - fish
B. Breathes with lungs - snake
3.
A. Has hair or fur - mouse
B. Has no hair or fur - frog
Here's a different key for the same four animals:
1.
A. Has four legs ... 2
B. Does not have 4 legs ... 3
2.
A. is warm-blooded - mouse
B. is cold-blooded - frog
3.
A. has fins - fish
B. has no fins - snake</span>
Answer:
The last one: dinosaur footprints preserved in mud turned to rock
Fossils have to be physical remains of an animal.
Hope this helps!
Answer:
sharks, rays, snakes, fishes, and insects
Explanation:
These ovoviviparous animals produce eggs, but instead of laying eggs, eggs develop inside the mother's body. The eggs are laid in the mother. After rocking, they stay in the mother for a while and feed there. Then the young are born live.
Ovoviparity is, therefore, a mixture of oviparous (animals that lay eggs) and viviparous (animals that develop in the mother’s body).
