Cracking the mystery of the 1st million years after the Age of Dinosaurs

March 14, 2020 10:32 AM

Sixty-six million years ago, a meteorite larger than Mount Everest slammed into Earth and 75 percent of species went extinct in a geologic blink of an eye, including nonavian dinosaurs. For decades, scientists worked to determine how the planet and living creatures rebounded, yet continued to know very little about the recovery. Until now. [...] "Now we have the animal fossils, the plant fossils, and we have an amazing timeline from the first one million years after the extinction of the dinosaurs, which just happens to be the origin of the modern world. We found these amazing fossils in one of the most poorly understood intervals of time." Discoveries near the BSCS Science Learning headquarters in Colorado shed light on the Rise of the Mammals (NOVA, 53 minutes)

It turns out the keys to the origins of modern life on Earth were buried under Colorado Springs -- Denver Museum of Nature & Science spent three years combing through the Corral Bluff area, just east of Colorado Springs, finding fossils that painted a picture of how the planet’s ecosystem recovered from the Cretaceous–Paleogene extinction event (Jesse Paul for Colorado Sun)

In fact, people have been examining the site for almost 100 years. But it wasn’t until Lyson cracked open a concretion a few years ago and found a mammal skull fossil that the site’s significance was really understood.
[...]
He realized there had to be more, and within five minutes, Lyson and his team had found another mammal skull in a concretion. And then many others were discovered.

“We’re going out there and finding more and more fossils,” Lyson said.

Before Lyons’ discovery, researchers at Corral Bluffs mostly ignored the “unassuming” concretions there.

“Concretions are just a type of rock that forms around a nucleus, like a bone,” Lyons said. “These concretions are not that common in sediments that preserve land-dwelling animals. Because of this, previous work at Corral Bluffs … they overlooked these unassuming rocks and the treasures they contained.”

The time period from which the fossils come is notoriously difficult to track down. “Together the fossil animals and the plants, with an excellent understanding of the time in these rocks, is really almost unheard of,” Miller said. “(We have) started to call this a paleontological trifecta.”

Fossil bonanza paints detailed picture of mammals after dinosaur extinction -- Treasure trove of fossils skyrockets our picture of post-extinction recovery. (Cathleen O'Grady for Ars Technica)

Paleontologists in Denver have uncovered a treasure trove of fossils that give a thrilling new insight into the rise of mammals after the extinction of the dinosaurs.

The discovery, detailed in a paper published [abstract] in Science, has yielded a colossal amount of data showing how tiny mammal species grew and diversified dramatically after the extinction. The finding throws a spotlight on a previously unknown part of our own history: the very early days of a period that eventually produced all current mammal species on Earth.

Fossil trove shows life's fast recovery after big extinction (Updated) (Malcolm Ritter for Phys.org)

The fossils were recovered from an area of steep bluffs covering about 10 square miles (25.9 square kilometers) near Colorado Springs, starting three years ago.

Lyson, of the Denver Museum of Nature and Science, found little in that area when he followed the standard practice of scanning for bits of bone. But that changed when he began looking instead for rocks that can form around bone. When the rocks were broken open, skulls and other fossils within were revealed.
[...]
The study reports on hundreds of mammal fossils representing 16 species and more than 6,000 plant fossils. Researchers also analyzed thousands of pollen grains to see what plants were alive at various times. Analysis of leaves indicated several warming periods during the period.

Here's the recovery story the fossils tell...

The article goes on to summarize the timeline for the next million years, as told in this collection of fossils.

And on the NOVA documentary: Stepping out of the dinosaurian shadow (Science Magazine abstract), and a summary of the documentary, with clips, from KPBS.

posted by filthy light thief (10 comments total)

I drove by Corral Bluffs every day for 18 months (commute). Who knew?! Off to rtfa, wtfv.
posted by j_curiouser at 10:58 AM on March 14, 2020

So...like a geode, but with a skull inside? Badass. I want one.
posted by sexyrobot at 11:25 AM on March 14, 2020 [4 favorites]

Interesting.

I wish there were a Nova format that edited the existing content down to 3 minutes and then added the same density of 1 Nova per 3 minutes to fill out the rest of the hour.
posted by Pembquist at 11:40 AM on March 14, 2020 [5 favorites]

I wish there were a Nova format that edited the existing content down to 3 minutes and then added the same density of 1 Nova per 3 minutes to fill out the rest of the hour.

Oh, you mean Nova like Nova was when it first started. It was a total information package early on. Now it's all "let me drag you slowly along with me while I reveal a few ideas". I miss the early version.
posted by hippybear at 11:58 AM on March 14, 2020 [5 favorites]

I'm greatly interested in reading the articles, but was skeptical that a Nova presentation would be anything but torture to watch. Sounds like others agree. It's a good time to be reading anyway.
posted by OHenryPacey at 12:04 PM on March 14, 2020

We visited the Denver Museum of Nature & Science's pop-up exhibit for the discovery back in January. They had fossil casts you could handle, wall murals depicting the life of the period, and some of the fossils on display, including a cross section of the rock layers showing the impact event.
posted by audi alteram partem at 12:18 PM on March 14, 2020 [3 favorites]

DMNS has a sample of the KT boundary layer under glass. It's about 2/3 through the Prehistoric Journey permanent exhibit. Right after the last dino repros, naturally.
posted by j_curiouser at 12:53 PM on March 14, 2020 [3 favorites]

The meteorite that annihilated the dinosaurs contained a large amount of iridium which triggered a nuclear reaction upon impact.
Some soils preserve this iridium ash layer really well and can be easily identified by geologists.
Sorry no citations for this.
posted by Narrative_Historian at 11:11 PM on March 14, 2020

Narrative, the KT boundary is what you're thinking of. Afaik, there is no nuclear reaction involved. Irridium is rare on Earth because it likes to be with iron / is heavy and sank to the iron core, but it is mixed into iron heavy asteroids.
posted by a robot made out of meat at 6:55 AM on March 15, 2020

Some soils preserve this iridium ash layer really well and can be easily identified by geologists.

I've seen it! The AMNH in nyc used to have ice cores from Antarctica on display (unfortunately, they...melted during hurricane Sandy and blackout...now they have plastic ones). So like this really long tube of ice and then there's just like, a little black line across it.
posted by sexyrobot at 9:16 AM on March 15, 2020 [2 favorites]