Fossil remains of tiny calcareous algae not only provide information about the end of the dinosaurs, but also show how the oceans recovered after the fatal asteroid impact. Experts agree that a collision with an asteroid caused a mass extinction on our planet, but there were hypotheses that ecosystems were already under pressure from increasing volcanism. "Our data speak against a gradual deterioration in environmental conditions 66 million years ago," says Michael Henehan of the GFZ [(GeoForschungsZentrum)] German Research Centre for Geosciences. Together with colleagues from the University of Yale, he published a study in the scientific journal Proceedings of the National Academy of Sciences (PNAS) that describes ocean acidification during this period.
He investigated isotopes of the element boron in the calcareous shells of plankton (foraminifera). According to the findings, there was a sudden impact that led to massive ocean acidification. It took millions of years for the oceans to recover from this acidification. "Before the impact event, we could not detect any increasing acidification of the oceans," says Henehan.
The impact of a celestial body left traces: the "Chicxulub crater" in the Gulf of Mexico and tiny amounts of iridium in sediments. Up to 75 percent of all animal species went extinct at the time. The impact marks the boundary of two geological eras – the Cretaceous and the Palaeogene (formerly known as the Cretaceous-Tertiary boundary).
Henehan and his team at Yale University reconstructed the environmental conditions in the oceans using fossils from deep-sea drill cores and from rocks formed at that time. According to this, after the impact, the oceans became so acidic due to the rainout of sulphuric acid from the vaporized crater rocks that organisms that made their shells from calcium carbonate could not survive. Because of this, as life forms in the upper layers of the oceans became extinct, carbon uptake by photosynthesis in the oceans was reduced by half. This state lasted several tens of thousands of years before calcareous algae spread again. However, it took several million years until the fauna and flora had recovered and the carbon cycle had reached a new equilibrium.
The researchers found decisive data for this during an excursion to the Netherlands, where a particularly thick layer of rock from the Cretaceous-Palaeogene boundary is preserved in a cave. "In this cave, an especially thick layer of clay from the immediate aftermath of the impact accumulated, which is really quite rare" says Henehan. In most settings, sediment accumulates so slowly that a rapid event such as an asteroid impact is hard to resolve in the rock record. "Because so much sediment was laid down there at once, it meant we could extract enough fossils to analyse, and we were able to capture the transition," says Henehan.
Most of the work was done at his former place of work, Yale University. Now, at the GFZ, he is using the infrastructure here and hopes that this will provide a major impetus for his work. "With the femtosecond laser in the HELGES laboratory, we are working to be able to measure these kinds of signals from much smaller amounts of sample," says Henehan. "This will in the future enable us to reconstruct disturbances in the Earth-climate system at really high resolution in time, even from locations with very low sedimentation rates."
Journal Reference:
Michael J. Henehan, Andy Ridgwell, Ellen Thomas, et al. Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact. Proceedings of the National Academy of Sciences, 2019; 201905989 DOI: 10.1073/pnas.1905989116
Related: New Evidence Supports Giant Asteroid Impact 12 800 Years Ago
(Score: 2, Insightful) by Anonymous Coward on Wednesday October 23 2019, @09:49AM (5 children)
We do have scientific evidence that dinosaurs existed. Jesus... not so much.
(Score: 2) by Freeman on Wednesday October 23 2019, @03:13PM
If you refudiate that fact that Jesus even existed at all, you've not done much research or are sticking your fingers in your ears while screaming.
Like here:
https://www.biblegateway.com/passage/?search=Acts+7:54-60 [biblegateway.com]
Whether or not you believe Jesus was who He said He was. Jesus's existence wasn't even argued against by Ancient Secular Scholars.
https://www.theguardian.com/world/2017/apr/14/what-is-the-historical-evidence-that-jesus-christ-lived-and-died [theguardian.com]
Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"
(Score: 2, Informative) by MindEscapes on Wednesday October 23 2019, @04:57PM (3 children)
Nor will we of you in say, 200 years, let alone 2000.
There is pretty much 0 scientific evidence that any of the rulers of any of the great civilizations of the world ever existed.
Now I'm not saying Jesus did or did not exist just that expecting scientific proof of a ripple on a pond thousands of years ago is simply impractical as a basis for believing in it.
We do have some documentation, human written so filled with agenda's, author's beliefs, and misunderstandings, of most of these great people in history that you can choose to trust in or not. Much of it has proven to carry verifiable truths, it just doesn't ensure the whole thing is truth.
Need a break? mindescapes.net may be for you!
(Score: 2) by PartTimeZombie on Wednesday October 23 2019, @08:05PM (2 children)
That is nonsense.
Look at the pictures in this piece. [wikipedia.org] That looks like pretty hard evidence for someone who lived 600 years before Christ.
(Score: 1) by MindEscapes on Thursday October 24 2019, @11:46AM (1 child)
Lets see, a building inscription, attributed to Nebuchadnezzar II based on the findings and other writings recorded of this leader around that time.
A coin with a face stamped on it, with an inscription of the name of Nebuchadnezzar II on it.
An artists illustration of what a scene with Nebuchadnezzar's dream interpretation by Daniel inspired by said story in the Bible.
There is more 'scientific evidence' of this sort on God, heck, even our current US currency is inscribed 'In God We Trust', a political piece for sure but there it is, none the less.
Basically, these are historical finds but all are human creations at the direction of, or inspired by, an individual believed to have existed and ruled at that time. Sure, it is the best we have, and there is enough volume of it we believe it to be true, but do you really believe his reign was solidified by listening to dream interpretations by an agent of God?
I will concede a bit, there are the Egyptian mummies still found intact in their sarcophagus. These have names inscribed on them so we make the assumption that the body inside belongs to said name but we have no way to know with certainty. There has been some DNA extracted I believe so we can link some descendants to these individuals, so I suppose we know the people existed, we still only have the assumption that the inscribed name and any related writings about them actually belong to the body there in.
Need a break? mindescapes.net may be for you!
(Score: 2) by PartTimeZombie on Thursday October 24 2019, @08:42PM
So 0 evidence? OK then.