Yes, some of them did, such as they do in this lifetime.
sea legs
No.
Yes
In prehistoric times Florida was underwater in the Siluarian Sea so you would find many sea creatures back then.
The hippo and prehistoric creatures
No
Yes, sea snakes do lay eggs. They typically lay their eggs on land, in sandy beaches or rocky crevices near the shore.
a sea turtle can lay 50-160 eggs but they lay 10 per minute.
Sea snakes do not lay eggs. They give birth to live young.
Salmon definitely go from the sea and up river to spawn (lay eggs)
no male sea turtles can also lay eggs when they are mid-aged.
No, but their close relatives were alive in prehistoric times