New clues about how life bounced back after the dinosaurs went extinct

Stacy Liberatore for Dailymail.com

19:04 13 May 2024, updated 19:44 13 May 2024



Thousands of fossils unearthed in Colorado have provided clues about how life rebounded after the asteroid that wiped out the dinosaurs 66 million years ago.

A team working at Corral Bluffs discovered a new species of mammal that suggested the Earth had returned to life within 300,000 years, giving way to mammals 30 times larger than those that survived the mass extinction.

The discoveries answered many questions about what happened in the first million years after the dinosaurs were killed, along with filling in gaps in the evolutionary tree of mammals.

One particular fossil was of a chinchilla-sized mammal that roamed the Earth 65 million years ago and was the ancestor of all modern ungulates such as pigs and cows—revealing just how diverse animals really followed the disaster.

“We didn’t know much about small mammals [that lived after the mass extinction]but now we have a complete skull and jaw that tells us about the group that gave rise to modern ungulates,’ paleontologist Tyler R. Lyson of the Denver Museum of Nature and Science told DailyMail.com.

Thousands of fossils unearthed in Colorado have provided clues about how life returned after the events that wiped out the dinosaurs 66 million years ago.
Scientists have recently discovered the first complete skull of a new species of mammal that is the ancestor of all ungulates – such as pigs and cows.
The team has been working in Corral Bluffs since 2016

“The base of the mammalian tree of life has long had an evolutionary gap,” Lyson said.

“The recent discovery of Militocodon lydae helps fill a gap between all of today’s ungulates.”

Militocodon lydae, the ancestor of pigs and cows, has been unearthed from rocks dating back some 61,000 years to the time of the dinosaurs’ extinction.

The tiny ancient mammal stood between nine and 14 inches and weighed just over two pounds – about the size of a large rat – and appeared about 600,000 years after the mass extinction.

The researchers found several teeth still embedded in the jaw, revealing what kinds of plants also thrived at the time.

The diet of the small mammals indicated that nutritious vegetation was beginning to grow in the area, allowing it to thrive in what was once a wasteland.

The new species was named in honor of Sharon Milito and Lyda Hill, two women Lyson said were very important to science and Colorado Springs — the city outside of Corral Bluffs, Lyson told DailyMail.com.

Scientists have long searched for clues about how life returned to the planet after an asteroid wiped out 75 percent of life on Earth.

Militocodon lydae was unearthed from rocks dating back to about 61,000 years after the dinosaurs went extinct. The ancient mammal was 9 and 14 inches long and weighed over two pounds
Plants returned hundreds of thousands of years later, but were very selective. As time went on, plants diversified and led to larger mammals that roamed the planet
The reason why Corral Bluffs is so rich in fossils may be due to the peculiar concretions, a type of groove, that forms around the fossils. Lyson compared finding fossils inside concretions to “opening an oyster shell and finding a pearl”. The image shows the remains of a pig-sized mammal

The 7.5-mile-wide asteroid was traveling at 27,000 miles per hour when it slammed into what is now the Gulf of Mexico and exited the Chicxulub crater.

The collision caused worldwide fires that released tons of soot, filling the sky and blocking the sun for two to 15 years.

“Plants came back hundreds of thousands of years after that, but they were very selective,” Lyson said.

“I think it was time and stability that led to the first diversity of plants and animals.”

The team also discovered new turtle species, which also show how life has experienced a diversification boom

The depth of the fossils, which included Carsioptychus—another extinct pig-sized herbivorous mammal—showed that about 300,000 years after the mass extinction, mammals experienced their first major increase in body size.

At this time, temperatures began to rise, by about another nine degrees Fahrenheit, and the landscape became a botanical habitat that flourished.

Lyson and his team found that these creatures were 30 times larger than the mammals that survived the killing of the dinosaurs, which also suggested that plants had also diversified.

The fossils also revealed that mmammals dominated life on the planet as nut trees were also the largest plant group in the area – replacing the dinosaurs that owned the planet.

“Here we saw large mammals feeding on plants, which is important because most of the survivors of the mass extinction were omnivores,” Lyson explained, noting that it took about 300,000 years for a stable environment to develop in this area.

And the diversity of mammals increased threefold.

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The next key jump in mammals was 700,000 years after the cataclysmic event of further warming.

“During this time, lentils and peas covered the Earth, which gave rise to even larger mammals,” Lyson said.

“These mammals are about the size of a small wolf and are larger than any mammal that lived alongside the dinosaurs.”

This was observed when the team discovered fossils of Ectoconus ditrigonus, which was a herbivore with five toes on all four limbs.

“This is a hundredfold increase in body size compared to mammals that survived the extinction,” Lyson said.

“Mammals wouldn’t go through this kind of rapid growth again for another 30 million years.”

The animal was about the size of a sheep with a long heavy tail.

He noted that the discoveries made in Colorado only reveal how life in the area rebounded.

“The recovery of life has not been the same everywhere on the planet,” Lyson said.

The reason why Corral Bluffs is so rich in fossils may be due to the peculiar concretions, a type of groove that forms around the fossils.

Lyson compared finding fossils inside concretions to “opening an oyster shell and finding a pearl”.

“When we started uncovering mammal fossils at Corral Bluffs, it was like going to the optometrist and the glass turned and everything came into focus,” he said.

“Suddenly the game was on and we knew exactly what to look for. All we had to do was find these strange concretions, break them open and see what amazing fossils were inside.”