5 ms·

If birds descended from dinosaurs, why are they warm-blooded? (2010)

53 points by networked 11y ago

ascotan 11y ago
This presupposes that dinosaurs are cold-blooded which apparently is a matter of dispute: http://www.livescience.com/51162-dinosaurs-warm-blooded-growth-rates.html http://www.livescience.com/51162-dinosaurs-warm-blooded-grow...
- dragonwriter 11y ago
  No, in fact, the whole point is discussion of the evolution of warm-bloodedness among dinosaurs. Are you just guessing what the content might be based on the headline and reacting based on that guess?
  - mchahn 11y ago
    > the whole point is discussion of the evolution of warm-bloodedness among dinosaurs. And the question of whether dinosaurs were really cold-blooded is obviously a part of that discussion.
- devishard 11y ago
  No, the article explicitly states that it is unknown which species were endothermic.
hoodoof 11y ago
Because dinosaurs were warm blooded.
- openstack 11y ago
  Then why did they go extinct?
  - hoodoof 11y ago
    Due to a gigantic asteroid strike. Interestingly, crocodiles, which are cold blooded creatures, survived OK.
    - MrQuincle 11y ago
      This article doesn't make the connection, but it's an interesting hypothesis to assume that all cold blooded creatures that were big couldn't maintain their body temperature after a drop in temperature from a comet impact, but that creatures that were small already were better in coping with fluctuations because of their smaller size.
      - TheCoreh 11y ago
        It's more likely that large creatures couldn't get enough food, because sunlight was blocked by dust clouds and a lot of plant life died as well. The percentage of Oxygen on the atmosphere might also have been affected, making large lifeforms unable to function efficiently enough.
      - greggman 11y ago
        The thought the latest theory was the entire earth was engulfed in flames from the impact and killed almost everything except stuff underground / underwater http://www.radiolab.org/story/dinopocalypse/ http://www.radiolab.org/story/dinopocalypse/
        kbart 11y ago
        I didn't listen to this audio, but if this were true, shouldn't geologist have already discovered a layer of ashes spanning the whole world?
        greggman 11y ago
        they did.
- yareally 11y ago
  Birds are also scientifically classified as dinosaurs[1]. > "Avialae ("bird wings") is a clade of dinosaurs containing their only living representatives, the birds." [1]https://en.wikipedia.org/wiki/Avialae https://en.wikipedia.org/wiki/Avialae
- bryanlarsen 11y ago
  As the article states, some dinosaurs were definitely warm blooded, some were definitely cold blooded, but where in the tree the transition happened is very much unknown.
mjn 11y ago
This review article may also be of interest, "The evolution of concepts on the evolution of endothermy in birds and mammals" (2004): https://www.researchgate.net/profile/Pawet_Koteja/publication/216812468_The_evolution_of_concepts_on_the_evolution_of_endothermy_in_birds_and_mammals/links/0deec52e0e3159ee5f000000.pdf https://www.researchgate.net/profile/Pawet_Koteja/publicatio... [pdf]
- joe_the_user 11y ago
  Interestingly enough, some fish also have the ability to heat parts of their bodies and the opah/moohfish seems to be fully endothermic. See: http://io9.gizmodo.com/behold-the-first-fully-warm-blooded-fish-known-to-scien-1704472418 http://io9.gizmodo.com/behold-the-first-fully-warm-blooded-f...
Qantourisc 11y ago
I suspect it's because birds fly high and in cold wind, they had to evolve, or they would crash down like a frozen cube (at the very least stiff muscles and wings are not beneficial to flight). Quite the pressure from survival of the fittest.
deleted 11y ago
[deleted]
YeGoblynQueenne 11y ago
>> "What we can see in the fossil record is a number of bird-like theropods with hair-like structures and simple downy feathers. Being mostly small creatures [they must have generated their own body heat] and evolved hairs and feathers to help retain the body heat they generated," says Willis. Is it possible that feathers evolved first, for some other reason, particularly mating displays, and, once evolved, opened the way to endothermy? [Disclaimer: I'm completely not a biologist at all, so this is probably a stupid question, but I seriously wonder nonetheless] Edit: Funny typo in the article. The phylogenetic tree of dinosaurs says: "Theropods (meating-eating dinosaurs)". Aye. They're dinosaurs that meet you and eat you.
cyberrod411 11y ago
"descended from" is kind of a common misconception about evolution. Birds and Dinosaurs have common ancestors. Earlier researchers thought they were closely related to reptiles, but more recent research has shown they have a lot more in common with birds. It's still somewhat of a mystery as to why dinosaurs went extincted. A very large asteroid did hit the Earth at the end of the Cretaceous. But there was a lot of other thing happening on Earth at that time. Pangea was breaking up and major waterways/oceans were opening up at that time, so there was likely major climate changes occurring, incearse Volcanism, etc..

53 points by networked 11y ago

This presupposes that dinosaurs are cold-blooded which apparently is a matter of dispute: http://www.livescience.com/51162-dinosaurs-warm-blooded-growth-rates.html http://www.livescience.com/51162-dinosaurs-warm-blooded-grow...

dragonwriter 11y ago
No, in fact, the whole point is discussion of the evolution of warm-bloodedness among dinosaurs. Are you just guessing what the content might be based on the headline and reacting based on that guess?
- mchahn 11y ago
  > the whole point is discussion of the evolution of warm-bloodedness among dinosaurs. And the question of whether dinosaurs were really cold-blooded is obviously a part of that discussion.
devishard 11y ago
No, the article explicitly states that it is unknown which species were endothermic.

hoodoof 11y ago

Because dinosaurs were warm blooded.

openstack 11y ago
Then why did they go extinct?
- hoodoof 11y ago
  Due to a gigantic asteroid strike. Interestingly, crocodiles, which are cold blooded creatures, survived OK.
  - MrQuincle 11y ago
    This article doesn't make the connection, but it's an interesting hypothesis to assume that all cold blooded creatures that were big couldn't maintain their body temperature after a drop in temperature from a comet impact, but that creatures that were small already were better in coping with fluctuations because of their smaller size.
    - TheCoreh 11y ago
      It's more likely that large creatures couldn't get enough food, because sunlight was blocked by dust clouds and a lot of plant life died as well. The percentage of Oxygen on the atmosphere might also have been affected, making large lifeforms unable to function efficiently enough.
    - greggman 11y ago
      The thought the latest theory was the entire earth was engulfed in flames from the impact and killed almost everything except stuff underground / underwater http://www.radiolab.org/story/dinopocalypse/ http://www.radiolab.org/story/dinopocalypse/
      - kbart 11y ago
        I didn't listen to this audio, but if this were true, shouldn't geologist have already discovered a layer of ashes spanning the whole world?
        greggman 11y ago
        they did.
yareally 11y ago
Birds are also scientifically classified as dinosaurs[1]. > "Avialae ("bird wings") is a clade of dinosaurs containing their only living representatives, the birds." [1]https://en.wikipedia.org/wiki/Avialae https://en.wikipedia.org/wiki/Avialae
bryanlarsen 11y ago
As the article states, some dinosaurs were definitely warm blooded, some were definitely cold blooded, but where in the tree the transition happened is very much unknown.

mjn 11y ago

This review article may also be of interest, "The evolution of concepts on the evolution of endothermy in birds and mammals" (2004): https://www.researchgate.net/profile/Pawet_Koteja/publication/216812468_The_evolution_of_concepts_on_the_evolution_of_endothermy_in_birds_and_mammals/links/0deec52e0e3159ee5f000000.pdf https://www.researchgate.net/profile/Pawet_Koteja/publicatio... [pdf]

joe_the_user 11y ago
Interestingly enough, some fish also have the ability to heat parts of their bodies and the opah/moohfish seems to be fully endothermic. See: http://io9.gizmodo.com/behold-the-first-fully-warm-blooded-fish-known-to-scien-1704472418 http://io9.gizmodo.com/behold-the-first-fully-warm-blooded-f...

Qantourisc 11y ago

I suspect it's because birds fly high and in cold wind, they had to evolve, or they would crash down like a frozen cube (at the very least stiff muscles and wings are not beneficial to flight). Quite the pressure from survival of the fittest.

deleted 11y ago

[deleted]

YeGoblynQueenne 11y ago

>> "What we can see in the fossil record is a number of bird-like theropods with hair-like structures and simple downy feathers. Being mostly small creatures [they must have generated their own body heat] and evolved hairs and feathers to help retain the body heat they generated," says Willis. Is it possible that feathers evolved first, for some other reason, particularly mating displays, and, once evolved, opened the way to endothermy? [Disclaimer: I'm completely not a biologist at all, so this is probably a stupid question, but I seriously wonder nonetheless] Edit: Funny typo in the article. The phylogenetic tree of dinosaurs says: "Theropods (meating-eating dinosaurs)". Aye. They're dinosaurs that meet you and eat you.

cyberrod411 11y ago

"descended from" is kind of a common misconception about evolution. Birds and Dinosaurs have common ancestors. Earlier researchers thought they were closely related to reptiles, but more recent research has shown they have a lot more in common with birds. It's still somewhat of a mystery as to why dinosaurs went extincted. A very large asteroid did hit the Earth at the end of the Cretaceous. But there was a lot of other thing happening on Earth at that time. Pangea was breaking up and major waterways/oceans were opening up at that time, so there was likely major climate changes occurring, incearse Volcanism, etc..