5 ms·

An asteroid wiped out dinosaurs – did it help birds flourish?

41 points by gardenfelder 3y ago

gardenfelder 3y ago
https://archive.ph/StNCT https://archive.ph/StNCT
yodon 3y ago
>“The signal from the fossil record is not ambiguous,” Dr. Berv said The fossil record says the asteroid had a big impact on bird evolution. A fancy new computer model trained on DNA data says it didn't. The computer model's results are surprising and not supported by the fossil record. I know where I'm placing my bets.
- TSiege 3y ago
  The fossil record could be incomplete, and both could be true. I've seen other studies hinting at bird evolution happened older than we thought
  - yodon 3y ago
    The fossil record is certainly incomplete, but it's also certainly more reliable than a new DNA model reporting conclusions that make no sense (the impact didn't impact bird evolution? There's no way that passes the smell test)
- RachelF 3y ago
  Yes, I had the same thought. The DNA data is completely uncalibrated. From the NYT article, it looks like they've beaten the DNA data until it supports their hypothesis.
nemo 3y ago
This computational model doesn't match the fossil record which suggests the flaw is in the model, not the evidence.
- greazy 3y ago
  They used the fossil record to fine tune the baysian phylogenetic model. So no this is not correct.
  - space_fountain 3y ago
    I think this might be wrong. The article ends with quotes from Jacob Berv. It says: > Jacob Berv, an evolutionary biologist at the University of Michigan who was not involved in the study, said that it illustrated state-of-the-art methods for crunching huge amounts of genetic data to reconstruct evolutionary history. But he did not agree with its conclusion. > If the new study was right, there should be fossils of all major groups of living birds from well before the asteroid impact. But almost none have been found. > “The signal from the fossil record is not ambiguous,” Dr. Berv said. > Dr. Berv suspects that the correct story comes from the fossils, and that most major groups of birds emerged after the asteroid impact. The potential problem with the new study, he said, is that it assumes that the bird DNA accumulated mutations at a steady rate from one generation to the next.
  - nemo 3y ago
    I'd suggest reading the article which quotes experts in the field explaining that the fossil record does not fit this model.
riazrizvi 3y ago
So looking at the timeline of DNA diversification in birds, the biggest spread occurred 10's millions of years before the asteroid mass extinction, and net there was not so much after the asteroid hit itself. Makes sense to me as I imagine birds were hit with devastated ecosystems and had to adapt, though I imagine their greater range made them more resilient.
nyrikki 3y ago
Link to more pnas text, as usual it doesn't match the times copy very closely. https://www.pnas.org/doi/10.1073/pnas.2319696121 https://www.pnas.org/doi/10.1073/pnas.2319696121
dang 3y ago
[stub for offtopicness]
- kjkjadksj 3y ago
  Just because there was genetic diversity before the asteroid does not mean it did not affect things. A human builds a shack in the woods and that has measurable impact in terms of ecosystem disturbance decades even centuries after its a ruin. An asteroid is going to do something.
  - dang 3y ago
    I feel like I caused this problem by replacing the article's title with "The asteroid that wiped out dinosaurs didn't impact bird evolution: new study". I wanted something less baity than the article's own title, in keeping with the site guideline: "Please use the original title, unless it is misleading or linkbait" - https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html. The problem is that it is too easy to object to. "Didn't impact" is too strong. Everything impacts everything, as you say—especially asteroids. But now we're in generic tangent territory, driven by a bad title rather than anything interesting (or indeed, anything at all) about the study. Since the edit made things worse, I'm going to drop it. Sorry.
- TSiege 3y ago
  This is a very strange argument. I don't see how you can say the asteroid had no impact. There were entirely new niches that opened up after the mass extinction. Birds by definition had to evolve into them after the impact since ~75% of species went extinct. I can believe that birds evolved before the impact, but to say it didn't impact bird evolution is like saying mammal evolution wasn't impacted by the impact because mammals pre-existed before then. Who knows if birds would be as dominant as they are today had the impact never have happened. Today there are almost twice as many species of birds as there are mammals. I think both can easily be true > When searching for fossils of the major groups of birds alive today, scientists have found almost none that formed before the asteroid hit. That striking absence has led to a theory that the mass extinctions cleared the evolutionary arena for birds, allowing them to explode into many new forms. But the new study came to a very different conclusion. “We found that this catastrophe didn’t have impact on modern birds,” said Shaoyuan Wu, an evolutionary biologist at Jiangsu Normal University in Xuzhou, China.
Steven420 3y ago
Seems strange that people still don't think of birds as dinosaurs (just going off the title)
- aikinai 3y ago
  Why does that seem strange? People who are interested will know or course, but to 99.99% of people, “dinosaur” specifically means lizards (often huge) that lived millions of years ago. Even the name means “terrible lizard” and a lot of people might remember that. They’re conceptually so far from birds that the relationship is naturally relegated to a tangential factoid.
  - jandrese 3y ago
    Conceptually they are very different than sparrows or robins, but if you get up close to a Cassowary one has the distinct impression of meeting a modern Utahraptor.
    - steve_adams_86 3y ago
      They're actually utahraptors hiding inside bird skins. They snuck out of the armageddon in costumes and they just wander around trying to act natural now.
- bobbylarrybobby 3y ago
  I mean, we don't think of ourselves as lobe-finned fish either.
  - Steven420 3y ago
    That's because we aren't lobe-finned fish... But birds are a type of dinosaur
    - zozbot234 3y ago
      Birds aren't just a "type" of dinosaurs, they're literally defined as the surviving dinosaurs and their closest extinct relatives. For all intents and purposes, what we call "birds" are simply dinosaurs.
kopirgan 3y ago
We will have to wait for fossils to confirm this.
underlogic 3y ago
Did an asteroid wipe out the dinosaurs? I think it was blood borne viruses transmitted by biting insects across the large surface area of the dinosaurs bodies. They had no immune system, short opportunity to adapt, only the smaller types lived.
- creatonez 3y ago
  Yes, the short answer is, it was an asteroid and the effects after that killed the (large, non-avian) dinosaurs. Other hypotheses do not have the same explanatory power and may only account for a minuscule and much slower influence leading up to the asteroid extinction. Survival after the impact was greatly influenced by the simple ability to acquire food, but also other adaptations such as the immune system and ability to fight off fungal infections. Flying birds in particular had an advantage because they could forage for seeds over a vast distance while other terrestrial species run out of food (the article's cited study may broadly agree with this as an advantage, but suggests not as much post-chixculub diversification as believed before, and shows pre-chixculub modern bird form examples) There is a good YouTube documentary on the matter, but it is long: https://www.youtube.com/watch?v=6DHgkMYgp7w https://www.youtube.com/watch?v=6DHgkMYgp7w
- nradov 3y ago
  You shouldn't be down voted. While that hypothesis is outside the scientific consensus and based on very limited, circumstantial evidence it isn't completely impossible. There could have been multiple contributing causes. https://press.princeton.edu/books/hardcover/9780691124315/what-bugged-the-dinosaurs https://press.princeton.edu/books/hardcover/9780691124315/wh...

41 points by gardenfelder 3y ago

https://archive.ph/StNCT https://archive.ph/StNCT

>“The signal from the fossil record is not ambiguous,” Dr. Berv said The fossil record says the asteroid had a big impact on bird evolution. A fancy new computer model trained on DNA data says it didn't. The computer model's results are surprising and not supported by the fossil record. I know where I'm placing my bets.

TSiege 3y ago
The fossil record could be incomplete, and both could be true. I've seen other studies hinting at bird evolution happened older than we thought
- yodon 3y ago
  The fossil record is certainly incomplete, but it's also certainly more reliable than a new DNA model reporting conclusions that make no sense (the impact didn't impact bird evolution? There's no way that passes the smell test)
RachelF 3y ago
Yes, I had the same thought. The DNA data is completely uncalibrated. From the NYT article, it looks like they've beaten the DNA data until it supports their hypothesis.

nemo 3y ago

This computational model doesn't match the fossil record which suggests the flaw is in the model, not the evidence.

greazy 3y ago
They used the fossil record to fine tune the baysian phylogenetic model. So no this is not correct.
- space_fountain 3y ago
  I think this might be wrong. The article ends with quotes from Jacob Berv. It says: > Jacob Berv, an evolutionary biologist at the University of Michigan who was not involved in the study, said that it illustrated state-of-the-art methods for crunching huge amounts of genetic data to reconstruct evolutionary history. But he did not agree with its conclusion. > If the new study was right, there should be fossils of all major groups of living birds from well before the asteroid impact. But almost none have been found. > “The signal from the fossil record is not ambiguous,” Dr. Berv said. > Dr. Berv suspects that the correct story comes from the fossils, and that most major groups of birds emerged after the asteroid impact. The potential problem with the new study, he said, is that it assumes that the bird DNA accumulated mutations at a steady rate from one generation to the next.
- nemo 3y ago
  I'd suggest reading the article which quotes experts in the field explaining that the fossil record does not fit this model.

riazrizvi 3y ago

So looking at the timeline of DNA diversification in birds, the biggest spread occurred 10's millions of years before the asteroid mass extinction, and net there was not so much after the asteroid hit itself. Makes sense to me as I imagine birds were hit with devastated ecosystems and had to adapt, though I imagine their greater range made them more resilient.

nyrikki 3y ago

Link to more pnas text, as usual it doesn't match the times copy very closely. https://www.pnas.org/doi/10.1073/pnas.2319696121 https://www.pnas.org/doi/10.1073/pnas.2319696121

dang 3y ago

[stub for offtopicness]

kjkjadksj 3y ago
Just because there was genetic diversity before the asteroid does not mean it did not affect things. A human builds a shack in the woods and that has measurable impact in terms of ecosystem disturbance decades even centuries after its a ruin. An asteroid is going to do something.
- dang 3y ago
  I feel like I caused this problem by replacing the article's title with "The asteroid that wiped out dinosaurs didn't impact bird evolution: new study". I wanted something less baity than the article's own title, in keeping with the site guideline: "Please use the original title, unless it is misleading or linkbait" - https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html. The problem is that it is too easy to object to. "Didn't impact" is too strong. Everything impacts everything, as you say—especially asteroids. But now we're in generic tangent territory, driven by a bad title rather than anything interesting (or indeed, anything at all) about the study. Since the edit made things worse, I'm going to drop it. Sorry.
TSiege 3y ago
This is a very strange argument. I don't see how you can say the asteroid had no impact. There were entirely new niches that opened up after the mass extinction. Birds by definition had to evolve into them after the impact since ~75% of species went extinct. I can believe that birds evolved before the impact, but to say it didn't impact bird evolution is like saying mammal evolution wasn't impacted by the impact because mammals pre-existed before then. Who knows if birds would be as dominant as they are today had the impact never have happened. Today there are almost twice as many species of birds as there are mammals. I think both can easily be true > When searching for fossils of the major groups of birds alive today, scientists have found almost none that formed before the asteroid hit. That striking absence has led to a theory that the mass extinctions cleared the evolutionary arena for birds, allowing them to explode into many new forms. But the new study came to a very different conclusion. “We found that this catastrophe didn’t have impact on modern birds,” said Shaoyuan Wu, an evolutionary biologist at Jiangsu Normal University in Xuzhou, China.

Steven420 3y ago

Seems strange that people still don't think of birds as dinosaurs (just going off the title)

aikinai 3y ago
Why does that seem strange? People who are interested will know or course, but to 99.99% of people, “dinosaur” specifically means lizards (often huge) that lived millions of years ago. Even the name means “terrible lizard” and a lot of people might remember that. They’re conceptually so far from birds that the relationship is naturally relegated to a tangential factoid.
- jandrese 3y ago
  Conceptually they are very different than sparrows or robins, but if you get up close to a Cassowary one has the distinct impression of meeting a modern Utahraptor.
  - steve_adams_86 3y ago
    They're actually utahraptors hiding inside bird skins. They snuck out of the armageddon in costumes and they just wander around trying to act natural now.
bobbylarrybobby 3y ago
I mean, we don't think of ourselves as lobe-finned fish either.
- Steven420 3y ago
  That's because we aren't lobe-finned fish... But birds are a type of dinosaur
  - zozbot234 3y ago
    Birds aren't just a "type" of dinosaurs, they're literally defined as the surviving dinosaurs and their closest extinct relatives. For all intents and purposes, what we call "birds" are simply dinosaurs.

kopirgan 3y ago

We will have to wait for fossils to confirm this.

underlogic 3y ago

Did an asteroid wipe out the dinosaurs? I think it was blood borne viruses transmitted by biting insects across the large surface area of the dinosaurs bodies. They had no immune system, short opportunity to adapt, only the smaller types lived.

creatonez 3y ago
Yes, the short answer is, it was an asteroid and the effects after that killed the (large, non-avian) dinosaurs. Other hypotheses do not have the same explanatory power and may only account for a minuscule and much slower influence leading up to the asteroid extinction. Survival after the impact was greatly influenced by the simple ability to acquire food, but also other adaptations such as the immune system and ability to fight off fungal infections. Flying birds in particular had an advantage because they could forage for seeds over a vast distance while other terrestrial species run out of food (the article's cited study may broadly agree with this as an advantage, but suggests not as much post-chixculub diversification as believed before, and shows pre-chixculub modern bird form examples) There is a good YouTube documentary on the matter, but it is long: https://www.youtube.com/watch?v=6DHgkMYgp7w https://www.youtube.com/watch?v=6DHgkMYgp7w
nradov 3y ago
You shouldn't be down voted. While that hypothesis is outside the scientific consensus and based on very limited, circumstantial evidence it isn't completely impossible. There could have been multiple contributing causes. https://press.princeton.edu/books/hardcover/9780691124315/what-bugged-the-dinosaurs https://press.princeton.edu/books/hardcover/9780691124315/wh...