4 ms·

I never understood why bipedal locomotion would evolve in dinosaurs. Especially since the article says it happened well before any kind of flight or even glidin

I never understood why bipedal locomotion would evolve in dinosaurs. Especially since the article says it happened well before any kind of flight or even gliding.

danieltillett 6y ago
Bipedal locomotion is more efficient in that it takes less energy to cover a certain distance on two legs than four.
- mrfusion 6y ago
  I never thought about that. I wonder why it hasn’t evolved more often then? Basically limited to humans and birds. (I guess kangaroos too?)
  - emmelaich 6y ago
    Many animals are occasionally bipedal. Apes and monkeys and similar of course. But also bears and no doubt many more.
    - dboreham 6y ago
      Domestic cats will stand up on their hind legs to see further.
      - mcv 6y ago
        Not of those are efficient runners in that position, though. It's a careful balancing act.
  - zebrafish 6y ago
    Speed vs. endurance. Depends on which is more valuable in a given environment.
    - 082349872349872 6y ago
      Predation leads to optimising for speed. Calorie cost isn't such an issue if one is either getting a meal or avoiding being a meal immediately the sprint is finished. Even within ancient to medieval cavalry this tradeoff existed; the horse one rode to the battle would often not be the same breed as the horse one rode in the battle. (cavalry having arisen in the first place because a slow horse is still much faster than a fast man. infantry that can't run can't regroup)
      - stan_rogers 6y ago
        Two critters threw a monkey wrench into that machine. We're one of them, canids are the other. Persistence hunting is a thing. Let them sprint; they'll have to sprint again when we get there. Sooner or later, they won't be able to sprint anymore.
      - dmurray 6y ago
        Fast men are very competitive with horses over long distances [0]. Horses have other advantages like being able to carry more weight and live off grass. [0] https://en.wikipedia.org/wiki/Man_versus_Horse_Marathon https://en.wikipedia.org/wiki/Man_versus_Horse_Marathon
        thaumasiotes 6y ago
        > Fast men are very competitive with horses over long distances [0]. This might be true, but the citation says the opposite: > In 2013, extensive forestry works meant the organizers had to modify the route considerably, resulting in a course of nearly 24 miles, instead of the usual route of just under 21 miles. Despite a very hot day, the longer and hillier course favoured the horses, with 2011 winner Beti Gordon comfortably beating the first man, Hugh Aggleton. > Following a number of criticisms of the extended course in 2013 and 2014, the course for 2015 was shortened back towards 21 miles. This provided a more even match between man and equine
        dmurray 6y ago
- missedthecue 6y ago
  Then why do four legged animals still exist? Especially animals that walk a lot. Elk, wolves, etc...
  - sharatvir 6y ago
    Could be misremembering but I recall reading that bipedalism in humans correlates with a narrowing of the birth canal, potentially increasing mortality during childbirth and also selecting for infants that are underdeveloped compared to other newborn mammals.
  - monocasa 6y ago
    They can reach higher top speeds.
- monkeycantype 6y ago
  In Christopher McDougall's book about running, which I think launched the chia pudding trend, he has a story about a researcher whose theory is that bipedal motion separates breathing rhythm from gait when running. A quadruped has to breathe in time with their gait, because internal organs push forward into the diaphragm when the front feet land. According to the researcher, this is my jogging humans can stay cool while chasing quadruped prey, which are pushed to overheating and exhaustion.
  - mcv 6y ago
    I once heard that a springbok is a much better long-distance runner than other animals because it breathes automatically while it runs. The running motion directly powers the breathing motion, making it use less energy. I can't find a quick source to back this up, though.
fhars 6y ago
Dinosaurs never evolved bipedal locomotion, they evolved from older, bipedal animals and later some of them reverted to quadrupedal locomotion.
- mcv 6y ago
  Sounds unlikely, considering crocodiles are their closest non-dinosaur relative.
  - cultofmetatron 6y ago
    Bipedal crocodilians were a thing at one point source: https://www.youtube.com/watch?v=QsmV34Co32c https://www.youtube.com/watch?v=QsmV34Co32c
    - mcv 6y ago
      Interesting. With most land-based animals being four-legged today, it's tempting to assume that that would always have been the advantage over two-leggednes, with the exception of a few specialised long-distance runners (us, ostriches and kangaroos, basically). But maybe it's today's animal shapes that are the exception.

I never understood why bipedal locomotion would evolve in dinosaurs. Especially since the article says it happened well before any kind of flight or even gliding.

danieltillett 6y ago

Bipedal locomotion is more efficient in that it takes less energy to cover a certain distance on two legs than four.

mrfusion 6y ago
I never thought about that. I wonder why it hasn’t evolved more often then? Basically limited to humans and birds. (I guess kangaroos too?)
- emmelaich 6y ago
  Many animals are occasionally bipedal. Apes and monkeys and similar of course. But also bears and no doubt many more.
  - dboreham 6y ago
    Domestic cats will stand up on their hind legs to see further.
    - mcv 6y ago
      Not of those are efficient runners in that position, though. It's a careful balancing act.
- zebrafish 6y ago
  Speed vs. endurance. Depends on which is more valuable in a given environment.
  - 082349872349872 6y ago
    Predation leads to optimising for speed. Calorie cost isn't such an issue if one is either getting a meal or avoiding being a meal immediately the sprint is finished. Even within ancient to medieval cavalry this tradeoff existed; the horse one rode to the battle would often not be the same breed as the horse one rode in the battle. (cavalry having arisen in the first place because a slow horse is still much faster than a fast man. infantry that can't run can't regroup)
    - stan_rogers 6y ago
      Two critters threw a monkey wrench into that machine. We're one of them, canids are the other. Persistence hunting is a thing. Let them sprint; they'll have to sprint again when we get there. Sooner or later, they won't be able to sprint anymore.
    - dmurray 6y ago
      Fast men are very competitive with horses over long distances [0]. Horses have other advantages like being able to carry more weight and live off grass. [0] https://en.wikipedia.org/wiki/Man_versus_Horse_Marathon https://en.wikipedia.org/wiki/Man_versus_Horse_Marathon
      - thaumasiotes 6y ago
        > Fast men are very competitive with horses over long distances [0]. This might be true, but the citation says the opposite: > In 2013, extensive forestry works meant the organizers had to modify the route considerably, resulting in a course of nearly 24 miles, instead of the usual route of just under 21 miles. Despite a very hot day, the longer and hillier course favoured the horses, with 2011 winner Beti Gordon comfortably beating the first man, Hugh Aggleton. > Following a number of criticisms of the extended course in 2013 and 2014, the course for 2015 was shortened back towards 21 miles. This provided a more even match between man and equine
        dmurray 6y ago
missedthecue 6y ago
Then why do four legged animals still exist? Especially animals that walk a lot. Elk, wolves, etc...
- sharatvir 6y ago
  Could be misremembering but I recall reading that bipedalism in humans correlates with a narrowing of the birth canal, potentially increasing mortality during childbirth and also selecting for infants that are underdeveloped compared to other newborn mammals.
- monocasa 6y ago
  They can reach higher top speeds.
monkeycantype 6y ago
In Christopher McDougall's book about running, which I think launched the chia pudding trend, he has a story about a researcher whose theory is that bipedal motion separates breathing rhythm from gait when running. A quadruped has to breathe in time with their gait, because internal organs push forward into the diaphragm when the front feet land. According to the researcher, this is my jogging humans can stay cool while chasing quadruped prey, which are pushed to overheating and exhaustion.
- mcv 6y ago
  I once heard that a springbok is a much better long-distance runner than other animals because it breathes automatically while it runs. The running motion directly powers the breathing motion, making it use less energy. I can't find a quick source to back this up, though.

fhars 6y ago

Dinosaurs never evolved bipedal locomotion, they evolved from older, bipedal animals and later some of them reverted to quadrupedal locomotion.

mcv 6y ago
Sounds unlikely, considering crocodiles are their closest non-dinosaur relative.
- cultofmetatron 6y ago
  Bipedal crocodilians were a thing at one point source: https://www.youtube.com/watch?v=QsmV34Co32c https://www.youtube.com/watch?v=QsmV34Co32c
  - mcv 6y ago
    Interesting. With most land-based animals being four-legged today, it's tempting to assume that that would always have been the advantage over two-leggednes, with the exception of a few specialised long-distance runners (us, ostriches and kangaroos, basically). But maybe it's today's animal shapes that are the exception.