Quote:
Originally Posted by Flyndaran
One problem is that not only that technological species would have to be unknown. All of its other high intelligence relatives would as well. For humans, all other primates would have to be missing from the fossil record.
There really aren't any non-mammalian animals on par with primates other than cephalopods. And I don't think it's possible for purely aquatic creatures to progress past middle stone age.
Of course stone age soft bodied invertebrates could have evolved and disappeared from the oceans many times without leaving anything we would identify as proof.
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For a pre-Mesozoic civilization, yes, your statement discards most scenarios. As bill pointed out, Corvids would challenge your statement, and that means some dinosaurs are valid candidates.
Radical modification of the basic primate form is in human's recent past, and while we've found fossil evidence of such things, its fairly incomplete, fairly recent, and we had a good idea of what were looking for. So a basic form could quickly change to something suited for technology without leaving many intermediate fossils.