Why are all the ‘prehistoric’ versions of animals so massive?

Question

We always hear about how big ancient sharks, alligators, birds were. What was the advantage of being such a massive size and what caused them to become smaller? To my understanding its best to be smaller because of the square-cube law, then why are there exceptions like whales?

In: 3

Answer 1

There were smaller animals around but people are interested in the big animals. Large animals like whales are so large it becomes difficult for a prey animal to tackle an adult. The availability of food and the presence of man led to the quaternary extinction event or the extinction of the megafauna https://youtu.be/Y3J9CzLW_p0