Sure, but there were plenty of carnivorous dinosaurs. There is a very good reason mammals didn't evolve into anything bigger than a shrew until after the dinosaurs went extinct. Dinosaurs and other reptiles had filled pretty much every evolutionary niche on the planet quite successfully. Slow, soft, weak humans would not have lasted long in such an environment.
Lifespan of pre-Noahic man? 900+ years, as the environment was a lot different than it is now.
What I mean by lifespan is the question of how long a primitive human would have lasted in an environment populated by large, predatory reptiles.
There was likely a water-vapor canopy surrounding the atmosphere that enabled tropical vegetation on Antarctica, lizards to grow huge, insects to become much larger.... and humans to live much longer
The Earth was a lot warmer back then? That may or may not be true, but why would that lead to humans living any longer? If anything, a warmer, wetter environment would be an even better incubator for such fun tropical diseases as malaria. Sorry, prehistoric humans lived lives that were nasty, brutish and short. Most would die by age 30. And this was in a world where the biggest land predator was a bear, not a T. Rex.
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