Lead author Emily Carlisle of Bristol's School of Earth Sciences said: "We pulled together thousands of fossils of placental mammals and were able to see the patterns of origination and extinction of the different groups. Based on this, we could estimate when placental mammals evolved."
Humans and dinosaurs living in harmony — that didn’t really happen, did it? (Credit: iurii/Shutterstock)
Did humans and dinosaurs live at the same time? What if humans and dinosaurs really coexisted?
This question is not an easy one to answer. Until recently, the available evidence overwhelmingly supported the idea that humans and dinosaurs did not coexist at the same time and place. Some claim that the fossil record shows no direct evidence of humans living alongside dinosaurs. But since birds are descendants of dinosaurs, some argue that they technically live alongside us today. And evidence from a 2023 study further challenges this debate.
How Long Ago Were Dinosaurs Alive?
The data here are quite solid. The non-avian dinosaurs died out 66 million years ago, likely when an asteroid struck Earth and the ensuing cataclysm wiped out a large percentage of life on the planet. This included almost every large organism, and most of the small ones as well.
In the aftermath, one relatively humble group was able to carve out a much larger footprint for itself: the mammals. These were the creatures that would one day lead to us, after much evolutionary progress and most of the 60-odd million years separating us from the end-Cretaceous mass extinction.
Read more: What Killed the Dinosaurs?
Humans and Dinosaurs Timeline
At some point in the past half-dozen million years, the last common ancestor of humans and chimpanzees and bonobos (our closest evolutionary relatives) split into two groups.
One of these would lead one day to humans, passing first through any number of intermediate groups of hominins. Modern humans are currently thought to have appeared around 300,000 years ago — more than 65 million years after the non-avian dinosaurs disappeared.
Read More: What Species Today Are Descendants of Dinosaurs?
Did Humans and Dinosaurs Live at the Same Time?
But, as you may have already pointed out: Not all the dinosaurs disappeared. Birds descended from some of the few dinosaur species to survive the end of the Cretaceous — likely a type of theropod.
So, in a technical sense, birds are indeed dinosaurs, and we are still living with them today. From this standpoint, then, the idea of humans and dinosaurs coexisting is not completely outlandish.
We eat dinosaurs, we keep them as pets, they pick at our snacks when we go to the beach. But, just as humans have evolved far from our mammalian ancestors 66 million years ago, birds have also changed significantly.
Read More:Take an In-Depth Look at What Dinosaurs Really Looked Like
New Evidence Points to Dinosaur and Human Coexistence
A 2023 study suggests that early mammals, including ancestors of humans and placental mammals like dogs, rabbits and cats, lived alongside dinosaurs before a massive asteroid impact wiped out the dinosaurs. This discovery challenges previous beliefs about the timeline of mammal evolution and suggests that mammals thrived after the extinction of the dinosaurs, leading to the diverse mammalian world we see today.
The study also questions the identity of a famous fossil, Brasilodon quadrangularis, which some researchers thought was an ancient mammal. The research argues that it might not be a mammal but rather an early mammalian relative, highlighting the complexity of identifying ancient creatures from the fossil record. Ultimately, the researchers and other paleontologists conclude that early mammals, ancestors of humans, coexisted with dinosaurs 66 million years ago.
Read More: Human Ancestors Must Have Co-Existed With Dinosaurs, Study Says
This article was originally published on April 24, 2020 and has since been updated with new information on the dinosaur and human coexistence debate. This story is part of an ongoing series covering readers’ biggest questions about human origins. Read more about ancient humans (and dinosaurs):