Learned articles will tell you that only around 1% of the potential fossil record has been found. The reasons pretty simple, very specific conditions have to be met for a skeleton to be fossilised, and most of the world for most of the geological time didnt produce the right conditions. Less than 100 complete-ish large dinosaur fossils exist, i think there actually isnt a complete tyrannosaurus rex, but the few partial ones can be learned from. Heck, the dodo only died out a few hundred years ago, and that only has 2 skeletons in existance.
Loads of species, potentially humanoid died out leaving no evidence. Its also true that many species could never have met. The time difference between the existance of triceratops and tyrannosaurus rex is greater than tyrannosaurus rex and now. Tectonic plate action also means a lot of the planets surface has been replaced. If mankind was wiped out tomorrow, Almost all evidence of us would disappear within 100,000 years and ALL evidence of us would disappear within a million years.
Given this, who knows, maybe we are ancient aliens...
Loads of species, potentially humanoid died out leaving no evidence. Its also true that many species could never have met. The time difference between the existance of triceratops and tyrannosaurus rex is greater than tyrannosaurus rex and now. Tectonic plate action also means a lot of the planets surface has been replaced. If mankind was wiped out tomorrow, Almost all evidence of us would disappear within 100,000 years and ALL evidence of us would disappear within a million years.
Given this, who knows, maybe we are ancient aliens...