Were dinosaurs alive at the same time as humans?

The reign of the dinosaurs (Review) ended approximately 66 million years ago with the Cretaceous-Paleogene (K-Pg) extinction event. This catastrophic event, widely attributed to a massive asteroid impact in what is now the Yucatán Peninsula, caused widespread environmental devastation, including tsunamis, firestorms, and a prolonged "impact winter" that halted photosynthesis. The impact, which released energy equivalent to millions of nuclear weapons, led to the extinction of roughly 75% of all species on Earth, including all non-avian dinosaurs.

Humans, on the other hand, are a relatively recent development in Earth's history. The earliest evidence of our species, *Homo sapiens*, appears in Africa around 300,000 years ago. This means there is a colossal time gap of about 65.7 million years between the last non-avian dinosaurs and the first humans. To put it into perspective, if the entire history from the beginning of dinosaurs to today were compressed into one calendar year, dinosaurs would have gone extinct in the third week of September, and humans would only appear on New Year's Eve.

The time after the dinosaur extinction, known as the Cenozoic Era, saw the rise and diversification of mammals. With the large reptilian predators gone, mammals, which had been small and relatively insignificant during the Mesozoic Era (the age of dinosaurs), were able to flourish and evolve into the diverse forms we see today, eventually leading to the emergence of primates and, much later, humans. Therefore, humans and non-avian dinosaurs never coexisted; our ancestors only began to thrive long after the dinosaurs' dramatic exit from the world stage.