Dear Readers, as I was innocently sitting at my desk writing yesterday’s blogpost, there was an enormous flash in the street outside, followed by an ear-splitting boom. I thought for a moment that an electricity substation had blown up, or something more sinister had happened, but as it turned out, it was just a thunderstorm directly overhead. However, for the plants and animals going about their lives 66 million years ago, the end of the world really was nigh, and, remarkably, scientists have found a site which preserves the remains of animals in the very immediate aftermath of the disaster.
The Tanis site in North Dakota was the site of a massive flood in the immediate aftermath of the asteroid impact, which took place at Chicxulub on the Yucatan peninsula in Mexico. It’s unusual to able to date a site so accurately, but the impact was so severe that it produced glass crystals called tektites, which rained down in the days and weeks following the event. The fish that are found at the Tanis site have these tektites in their gills, which indicates that they must have died very shortly after the asteroid hit. The chemical signature of the tektites matches that on the impact site in Mexico, and the rock formation that they are preserved in is also characteristic of the aftermath of the explosion.
The site has been somewhat controversial – the original results, in 2019, were published in New Yorker magazine rather than in a scientific journal. However, a continuous stream of interesting fossils has been discovered, including, in 2021, the remains of a turtle impaled on a branch. The animal was probably about five years old, and had already escaped being eaten by a crocodile, judging by the bite marks on its shell. The lead scientist, Robert dePalma, explained the fossil in New Scientist in 2021:
“First, it would have experienced an odd seismic jolt, some minutes after the impact,” DePalma told the conference. “And then it would have seen tiny, red-hot glass beads [in the sky] as the ejecta would have started to come in from the Chicxulub site. Then, the surge rushed up, about 10.5 metres in depth. At that point, he or she got impaled by a branch. So it was a very bad day for the turtle.”
And today, The Guardian reports that the thigh bone of a small dinosaur, a Thescelosaurus neglectus has been found, perfectly preserved (even the skin can be seen), with fragments of debris from the explosion embedded in the bone.
It is astonishing to think that there is a site that preserves the remains of animals actually killed during the aftermath of the asteroid strike, and the BBC think so too, as they are in the process of making a documentary about the site (featuring David Attenborough no less), so UK viewers keep your eyes skinned – it will be called ‘Dinosaurs – The Final Day’. I suspect that the Tanis site will continue to produce fascinating details of this extraordinary day in the history of life on this planet. And although it was a bad day for the poor dinosaurs, it also cleared the way for the rise of mammals and for those other dinosaurs, the birds. It makes me think about how resilient life is, and how, pragmatically, nature seems to take lemons and make lemonade with them. Which, strangely enough, I find rather comforting.