I find that hard to fathom. Over 80 MM years, it’s environment didn’t change enough to apply any adaptive pressure.
I find that hard to fathom.
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Pun?
(very subtle : ) )
Well, they say Sharks haven't 'evolved' for millions(tens/hundreds/ of?) years. Which isn't really true, but is as true as the idea this fish hasn't evolved.
I imagine it used to grow much larger. As far as 'adaptive pressure', the pressure only comes if something threatens the viability of a species. What would these things have to fear at that depth ?