Etiquette is about all of human social behavior. Behavior is regulated by law when etiquette breaks down or when the stakes are high - violations of life, limb, property and so on. Barring that, etiquette is a little social contract we make that we will restrain some of our more provocative impulses in return for living more or less harmoniously in a community.
The early Triassic was a period when the planet was recovering from the worst mass extinction it had ever known - that was the end Permian extinction, where climate change caused in part by mega-volcanic eruptions wiped out ninety-five percent of life on Earth. It took about ten or twenty million years for the planet's ecosystems to stabilize. During that time you saw a lot of weird, out-of-balance ecosystems where, for example, crocodile-like predators ripped the crap out of each other along the coasts.