230 million years ago Dinosaurs first appeared on earth, but was there apex predator like the size of a mouse ever existed? New research finds shocking details

Dinosaurs first appeared roughly 230 million years ago and eventually became the dominant land animals, holding that status until an asteroid struck Earth 66 million years ago, causing a mass ‌extinction of ⁠species. Mammals during the age of dinosaurs thrived in ecological niches perfect for small body sizes like insectivores and seed eaters.