The Chicxulub crater
Whoa.
Paleontologists have found a fossil site in North Dakota that contains animals and plants killed and buried within an hour of the meteor impact that killed the dinosaurs 66 million years ago. This is the richest K-T boundary site ever found, incorporating insects, fish, mammals, dinosaurs and plants living at the end of the Cretaceous, mixed with tektites and rock created and scattered by the impact. The find shows that dinosaurs survived until the impact.
The beginning of the end started with violent shaking that raised giant waves in the waters of an inland sea in what is now North Dakota.
Then, tiny glass beads began to fall like birdshot from the heavens. The rain of glass was so heavy it may have set fire to much of the vegetation on land. In the water, fish struggled to breathe as the beads clogged their gills.
The heaving sea turned into a 30-foot wall of water when it reached the mouth of a river, tossing hundreds, if not thousands, of fresh-water fish — sturgeon and paddlefish — onto a sand bar and temporarily reversing the flow of the river. Stranded by the receding water, the fish were pelted by glass beads up to 5 millimeters in diameter, some burying themselves inches deep in the mud. The torrent of rocks, like fine sand, and small glass beads continued for another 10 to 20 minutes before a second large wave inundated the shore and covered the fish with gravel, sand and fine sediment, sealing them from the world for 66 million years.
This unique, fossilized graveyard — fish stacked one atop another and mixed in with burned tree trunks, conifer branches, dead mammals, mosasaur bones, insects, the partial carcass of a Triceratops, marine microorganisms called dinoflagellates and snail-like marine cephalopods called ammonites — was unearthed by paleontologist Robert DePalma over the past six years in the Hell Creek Formation, not far from Bowman, North Dakota. The evidence confirms a suspicion that nagged at DePalma in his first digging season during the summer of 2013 — that this was a killing field laid down soon after the asteroid impact that eventually led to the extinction of all ground-dwelling dinosaurs. The impact at the end of the Cretaceous Period, the so-called K-T boundary, exterminated 75 percent of life on Earth.
The BBC did a documentary about it a couple of years ago.
Scientists who drilled into the impact crater associated with the demise of the dinosaurs summarise their findings so far in a BBC Two documentary on Monday.
The researchers recovered rocks from under the Gulf of Mexico that were hit by an asteroid 66 million years ago.
The nature of this material records the details of the event.
It is becoming clear that the 15km-wide asteroid could not have hit a worse place on Earth.
The shallow sea covering the target site meant colossal volumes of sulphur (from the mineral gypsum) were injected into the atmosphere, extending the “global winter” period that followed the immediate firestorm.
Had the asteroid struck a different location, the outcome might have been very different.
“This is where we get to the great irony of the story – because in the end it wasn’t the size of the asteroid, the scale of blast, or even its global reach that made dinosaurs extinct – it was where the impact happened,” said Ben Garrod, who presents The Day The Dinosaurs Died with Alice Roberts.
All the food went away, so everything died.
Editing to add: H/t Mona Albano
I’ve wondered for some time if somebody might find a deposit like this from the K-Pg impact. Pompeii for dinosaurs (and fish).
This one sounds really astonishing.
We live in exciting times.
Saw that in the NYT too, and “whoa” was my response.
Radiolab did a beautiful piece on this a few years ago:
https://www.youtube.com/watch?v=ZYoqtBEzuiQ
Oops, it was the New Yorker where I read it: https://www.newyorker.com/magazine/2019/04/08/the-day-the-dinosaurs-died
It also goes into eye-popping detail on the asteroid strike and the not just global but interplanetary effects of the cataclysm.
Ooh thanks.
Just read the New Yorker piece. WHOA indeed! If it all pans out, it truly is a remarkable find. I got goosebumps reading the story, which is well written by someone who knows enough about paleontology to get the details right. (Douglas Preston: https://en.wikipedia.org/wiki/Douglas_Preston) My Pompeii comment above is apt for not only the degree of preservation they seem to be finding, but also the minute by minute reconstruction of the sequence of events at that site on that day. It is amazing to be able to recover that degree of temporal detail after more than sixty million years. Sixty million years from now, whoever or whatever is around digging up our remains will be hard pressed to temporally distinguish our present era from that of our Neanderthal cousins. Being able to reconstruct such an event so long after is just so mind-bogglingly cool! More of that, please!
Another paleontologist’s perspective on the site and its possible future: https://www.facebook.com/thomas.holtz/posts/10107946946367628
…and here’s the open access paper:
https://www.pnas.org/content/pnas/early/2019/03/27/1817407116.full.pdf
and supplementary material
https://www.pnas.org/content/pnas/suppl/2019/03/27/1817407116.DCSupplemental/pnas.1817407116.sapp.pdf
Thanks YNnB.