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
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New evidence supports giant asteroid impact 12 800 years ago
A research team from South Africa has discovered new evidence that suggests Earth was struck by an asteroid or meteorite 12 800 years ago. The event resulted in global consequences and the extinction of many species at the period of an episode called Younger Dryas. The study was published on October 2, 2019.
[...] Thackeray, along with researcher Philip Pieterse from the University of Johannesburg and Professor Louis Scott of the University of the Free State, found the evidence from a core drilled in a peat deposit, remarkably in a sample approximately 12 800 years old.
"Our finding at least partially supports the highly controversial Younger Dryas Impact Hypothesis (YDIH). We seriously need to explore the view that an asteroid impact somewhere on earth may have caused climate change on a global scale, and contributed to some extent to the process of extinction of large animals at the end of the Pleistocene, after the last ice age," Thackeray stated, noting that meteorites are abundant in platinum.
"Without necessarily arguing for a single causal factor on a global scale, we cautiously hint at the possibility that these technological changes, in North America and on the African subcontinent at about the same time, might have been associated indirectly with an asteroid impact with major global consequences," said Thackeray. "We cannot be certain, but a cosmic impact could have affected humans as a result of local changes in the environment and the availability of food resources, associated with sudden climate change."
The team gathered evidence from a pollen at Wonderkrater to show that around 12 800 years ago, a temporary cooling occurred, which is linked to the Younger Dryas temperature drop. Some scientists said this cooling in widespread sites could at least have been potentially associated with the worldwide dispersal of atmospheric dust that is rich in platinum. Furthermore, a large crater has also been found in northern Greenland beneath the Hiawatha Glacier.
"There is some evidence to support the view that it might possibly have been the very place where a large meteorite struck the planet earth 12 800 years ago," Thackeray explained. "If this was indeed the case, there must have been global consequences."
Reference:
"The Younger Dryas interval at Wonderkrater (South Africa) in the context of a platinum anomaly" - Thackeray, J.F. et al. - Palaeontologia Africana - DOI: https://hdl.handle.net/10539/28129
(Score: 3, Interesting) by turgid on Tuesday October 22 2019, @09:10PM (1 child)
One day the Market will prove to patriotic Climate Change deniers that science was right,
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 3, Funny) by PartTimeZombie on Tuesday October 22 2019, @09:47PM
Thanks for the nice word salad. [yourdictionary.com]
(Score: 0) by Anonymous Coward on Tuesday October 22 2019, @10:26PM (14 children)
Wonder how dino tastes? I tried frog, snake meat, alligator meat, well that's about it. Not that good, steak, pulled pork, lambchop, even venison was better.
(Score: 2) by PartTimeZombie on Tuesday October 22 2019, @10:33PM (10 children)
Kangaroo is quite nice, so is Ostrich.
Dinosaur might be a sort of quantity over quality sort of situation. I mean, if you could bring down one of these [wikipedia.org] you're probably feeding the village for a fair old while.
(Score: 1, Funny) by Anonymous Coward on Wednesday October 23 2019, @12:38AM (8 children)
The problem with television is that morons like you think The Flintstones was a documentary. Dinosaurs and cavemen did not coexist, so if you took one down there would be no village to feed. The only reason you see pictures of Jesus riding a dinosaur is that his father gave him a time machine for Christmas.
(Score: 2) by driverless on Wednesday October 23 2019, @01:18AM
Yeah, everyone knows that cavemen rode around on mammoths, and on Sunday, mastodons [youtube.com].
They also cooked meals in volcanoes.
(Score: 2) by PartTimeZombie on Wednesday October 23 2019, @01:36AM (6 children)
You must be fun at parties.
Those pictures are jokes too. Nobody really believes that stuff.
(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.
(Score: 2) by driverless on Wednesday October 23 2019, @01:15AM
Ostrich is pretty gamey. Kangaroo is nice enough, it's sold here as kat fud, cheaper than most of the alternatives.
(Score: 4, Funny) by RamiK on Tuesday October 22 2019, @11:12PM (2 children)
Like chicken. No. Really. Chickens are tiny, ugly and mean spirited dinosaurs.
compiling...
(Score: 3, Insightful) by KritonK on Wednesday October 23 2019, @07:55AM
So are ostriches, but chicken is white meat, while ostrich is red meat. I wonder what kind of meat dinosaurs were. Like birds, I suppose it depends on the dinosaur.
(Score: 2) by Freeman on Wednesday October 23 2019, @03:18PM
My 4 yr old chases chickens and catches them. They are slow, dumb, and only some of them are mean. You're probably thinking about the roosters. There's at least one rooster on my parent's property that got deep sixed, because he was mean.
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) by inertnet on Tuesday October 22 2019, @10:46PM (1 child)
That layer of mud looks about 10 cm thick and lies 8550 km away from the crater (measured on Google Earth). That was an 'impressive' impact.
(Score: 2) by legont on Wednesday October 23 2019, @03:00AM
Chances are it will happen again before too long. What is too long? Before we solve the issue.
"Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.