I Talk To Mike Archer
Here are some questions I asked a Professor l Mike Archer. He is a professional Paleontologist. He gave me a knowledgeable understanding on the questions I gave him. He workds in the University Of NSW.
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What made them extinct? They aren't extinct; birds are dinosaurs that survived the meteor impact at 65 million years ago. Non-avian dinosaurs however, almost certainly died at the end of the Cretaceous because of the meteor impact.
Which countries have they been found in? All continents including Antarctica.
How did crocodiles and sharks survive? Good question; no-one knows, but clearly they did.
What is the oldest dinosaur? Not sure about the exact one, but they are first found in the Triassic Period.
How did they communicate? Sounds (calls) were clearly important but no doubt body movements would have been important as well. Perhaps smell communicated sexual willingness as it does in some snakes today. It's possible also that colour communicated feelings as they do for example in living Chameleons.