At https://phys.org/news/2020-05-ancient-giant-armored-fish-fed.html … another example of evolution reproducing similar niche feeding habitats as a result of similarities in niche environments. These concern different geological periods. A reptile in one period is superseded by a mammal in a later period but similarities in behaviour and feeding habits remain – simply because a niche environment has become vacant. In this instance we begin with modern basking sharks. No sharp teeth and predatory hunting here as they feed by opening big mouths that filter plankton and small sea creatures. It's a whale like shark in other words. Well, it seems there were big fish doing something similar way back in the Devonian, 380 million years ago. Not only that but fish that were related were predatory – just like the shark family. The same feeding pattern has been seen in giant armoured fish in the Devonian, and again in another fish species that lived around 200 million years ago. Filling a niche environment one might say.