Niche Evolution Hypothesis

A few minutes ago I came across this video which described a fossilized "finger" that is purported to be 100 million years old. It reminded me of a thought that I had a couple of days ago when a stray thought concerning Passenger Pigeons (Ectopistes migratorius) and the role it used to fill in its ecology (there were billions of them). Nature tends to obhur a vacuum. Consequently animals will evolve to fill a particular niche in an environment. There are instances of birds filling the roles of mammals (oft cited Kiwi Birds) and vice versa (bats). Frequently there is an island which has separated from a larger land mass (eg Madagascar) where the evolution of animals put some species into the role of others.

What if intelligence or some function which has intelligence as a byproduct is a niche which exists. Certainly dinosaurs had sufficient millions of years to create an intelligent species if it is an evolutionary imperative. Looking at humans, we have filled that niche possibly multiple times. Under the Toba catastrophe theory the population of humans was reduced to less than 10,000 (I have heard less than 1,000. While I am not suggesting that there was a human mammal 100 million years, it doesn't preclude the possibility that there wasn't a analogous development or convergent evolution:

Source
In this illustration one can see about 100 million years ago a marine reptile (Ichthyosaur) and our present day dolphins evolved both analogous physiological structures but also behaviours (hemispheric sleep strategy). It isn't to much of a leap to suppose a similar evolution might have constructed a "human" at about the same time.