Evolution: driven by extinctions: Chixculub in the Spring (Evolution)

by David Turell , Wednesday, February 23, 2022, 16:44 (794 days ago) @ David Turell

Further research confirms:

https://phys.org/news/2022-02-dinosaurs.html

"When the meteorite impacted Earth, it rocked the continental plate and caused huge waves in water bodies, such as rivers and lakes. These waves moved enormous volumes of sediment that engulfed fish and buried them alive, while impact spherules (glass beads of Earth rock) rained down from the sky, less than an hour after impact. Today, the event deposit of Tanis in North Dakota preserves a fossilized ecosystem that includes paddlefishes and sturgeons, which were direct casualties of the event.

"The fossil fishes were exceptionally preserved, with their bones showing almost no signs of geochemical alteration. Melanie During, researcher from Uppsala University and the VU Amsterdam and lead author of the publication, went onsite to excavate the precious specimens: "It was obvious to us that we needed to analyze these bones to get valuable information about the moment of the impact," she explains.

"The team came to the ESRF, a particle accelerator that produces the world's brightest X-rays, with a partial fish specimen and representative sections of the bones and carried out high-resolution synchrotron X-ray tomography.

"The ESRF is the perfect tool to research these kinds of samples and the facility has developed unique expertise in paleontology over the last two decades. "Thanks to the ESRF's data, we found that the bones registered seasonal growth, very much like trees do, growing a new layer every year on the outside of the bone," explains Sophie Sanchez of Uppsala University, and visiting scientist at the ESRF.

***

"The findings will aid future research into the selectivity of the mass extinction: In the Northern Hemisphere, it was spring and therefore the reproduction cycles of organisms were starting, only to be abruptly stopped. Meanwhile, it was autumn in the Southern Hemisphere, where many organisms were likely preparing for winter. In general, it is well understood that organisms who were exposed died virtually immediately. So those sheltering in caves or burrows because they were hibernating were far more likely to survive into the Paleogene. "Our results will help to uncover why most of the dinosaurs died out while birds and early mammals managed to evade extinction," concludes During."

Comment: this is mainly a repeat of the previous study. I guess new info is added. The amazing point is how much clever humans can invent to study the deep past.