An astonishing new study concludes that human ancestors survived the asteroid impact that killed the dinosaurs. This fact, and other new insights into the timeline of animal evolution, are rocking the scientific community.
Researchers conducted a thorough analysis of the fossil record. They discovered that placental mammals – a group that includes humans, dogs, and even bats — originated in the Cretaceous period.
This suggests that these mammals shared the planet with dinosaurs for a brief period before the mass extinction event. This finding that throws a curveball into the long-standing debate among researchers.
Until now, it was a point of contention whether placental mammals walked alongside dinosaurs or only came into existence after the large reptiles had vanished.
Fossils from placental mammals only showed up in rocks less than 66 million years old. That was the time when an asteroid had a fateful encounter with Earth.
This evidence seemed to suggest that placental mammals appeared only after the dinosaurs’ dramatic exit. However, molecular data has been hinting at an older age for this group. This finding has completely complicated the narrative.
In an exciting breakthrough, a team of paleobiologists from the University of Bristol and the University of Fribourg published a paper in the journal Current Biology. In this paper, they offer a new perspective.
Using statistical analysis, they dissected the fossil record. Their findings confirmed that placental mammals did indeed originate before the dinosaur extinction event. This incident is also known as the catastrophic Cretaceous-Paleogene (K-Pg) mass extinction.
Shockingly, their conclusion means that placental mammals, the ancestors of humans, briefly co-existed with dinosaurs.
However, the story doesn’t end there. Their research shows that placental mammals began to flourish only after the asteroid impact wiped out the dinosaurs. This suggests that the removal of dinosaurs as competition allowed these mammals to diversify and thrive.
To reach this conclusion, the scientists embarked on a mission to collect extensive fossil data from placental mammal groups. This fossil data went all the way back to the mass extinction event, 66 million years ago.
“We pulled together thousands of fossils of placental mammals and were able to see the patterns of origination and extinction of the different groups,” explained Emily Carlisle of Bristol’s School of Earth Sciences, the lead author of the paper. “Based on this, we could estimate when placental mammals evolved.”
Co-author Daniele Silvestro from the University of Fribourg elaborated on their methodology.
“The model we used estimates origination ages based on when lineages first appear in the fossil record and the pattern of species diversity through time for the lineage. It can also estimate extinction ages based on last appearances when the group is extinct.”
The researchers also highlighted how examining both the origins and extinctions can provide a clearer picture of the impact of major events. One such example is the K-Pg mass extinction.
Professor Phil Donoghue, a co-author from Bristol, stated, “By examining both origins and extinctions, we can more clearly see the impact of events such as the K-Pg mass extinction or the Paleocene-Eocene Thermal Maximum (PETM).”
Even more intriguing is the finding that primates, the group that includes the human lineage, as well as Lagomorpha (rabbits and hares) and Carnivora (dogs and cats), evolved just before the K-Pg mass extinction.
This implies that our very own ancestors once rubbed shoulders with dinosaurs.
Following the cataclysmic asteroid impact, placental mammals demonstrated a rapid diversification. The extinction of the dinosaurs might have paved the way for the successful expansion of our mammalian ancestors.
If that asteroid had not killed the dinosaurs, the world as we know it today would be much different, indeed.
The Cretaceous-Paleogene (K-Pg) mass extinction event is also known as the K-T extinction event (Cretaceous-Tertiary extinction event). It is one of the most well-known extinction events in Earth’s history.
The K-Pg occurred approximately 66 million years ago, marking the end of the Cretaceous period and the beginning of the Paleogene period.
Here’s an in-depth look at this crucial turning point in Earth’s history:
The prevailing hypothesis about the cause of the K-Pg extinction event is that a large asteroid or comet struck the Earth near the present-day Yucatán Peninsula in Mexico. It was approximately 10 to 15 kilometers in diameter, and it created the Chicxulub Crater.
The impact would have released an enormous amount of energy. This would have caused fires, tsunamis, severe storms with high winds.
In addition, a subsequent “impact winter” would have resulted, caused by debris thrown into the atmosphere blocking sunlight. This would have drastically altered the Earth’s climate in the following months and years. There would have been a devastating impact on life across the globe.
The most famous victims of the K-Pg extinction event are the non-avian dinosaurs. However, many other organisms also became extinct. These included certain groups of mammals and birds, as well as marine reptiles and invertebrates. In total, it’s estimated that about 75% of all species on Earth disappeared.
Some species managed to survive the mass extinction. This set the stage for the world’s biodiversity today.
These include birds, small mammals, amphibians, crocodiles, turtles, and many invertebrates. Some of these creatures were likely able to endure the harsh conditions because they were small. They could find shelter, and they didn’t require a lot of food to survive.
Some plants and marine plankton also survived. Their recovery and evolution played a key role in shaping the post-K-Pg world.
The recovery of life after the K-Pg extinction event took millions of years. In the absence of the dinosaurs, mammals underwent significant adaptive radiation. They began diversifying and evolving to fill many of the ecological roles left vacant.
There’s a distinctive layer of sediment in the Earth’s crust worldwide, known as the K-Pg boundary. It is full of iridium, a rare metal on Earth but more common in asteroids and comets.
This layer serves as the primary evidence for the asteroid impact hypothesis. Fossil evidence also shows a dramatic decrease in biodiversity following this layer.
The K-Pg extinction event continues to be a subject of intense scientific study. The asteroid impact hypothesis is the most widely accepted cause.
However, other factors such as intense volcanic activity in the Deccan Traps (modern-day India) and potential climate change leading up to the event are also considered as contributing factors to the extinction event.
Keep in mind that our understanding of the K-Pg extinction event is continually evolving. New research and technology provide us with more detailed and precise information every day about this fascinating period in Earth’s history.