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Earth Science

Birds Had To Relearn Flight After Meteor Wiped Out Dinosaurs, Fossil Records Suggest (theguardian.com) 60

An anonymous reader quotes a report from The Guardian: Birds had to rediscover flight after the meteor strike that killed off the dinosaurs, scientists say. The cataclysm 66 million years ago not only wiped out Tyrannosaurus rex and ground-dwelling dinosaur species, but also flying birds, a detailed survey of the fossil record suggests. As forests burned around the world, the only birds to survive were flightless emu-like species that lived on the ground. The six to nine-mile-wide meteor struck the Earth off the coast of Mexico, releasing a million times more energy than the largest atomic bomb. Hot debris raining from the sky is thought to have triggered global wildfires immediately after the impact. It took hundreds or even thousands of years for the world's forests of palms and pines to recover. Fossil records from New Zealand, Japan, Europe and North America, all show evidence of mass deforestation. They also reveal that birds surviving the end of the Cretaceous period had long sturdy legs made for living on the ground. They resembled emus and kiwis, said the researchers whose findings are reported in the journal Current Biology.
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Birds Had To Relearn Flight After Meteor Wiped Out Dinosaurs, Fossil Records Suggest

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  • Never understood how birds are the only remaining dinosaurs... wonder what made dinos so vulnerable to this event, where many other large species (crocs, turtles, fish, etc) survive to this day. One might think that some small dinosaurs, or aquatic/marine species would have found a niche on some continent. Population bottleneck, I guess. Imagine if no dinosaurs at all had survived... maybe we'd have a lot more large insects and bats species filling the skies.
    • by Anonymous Coward

      Never understood how birds are the only remaining dinosaurs...

      Likely nothing more than dumb luck - a few tens of a handful of species (or maybe even less) is probably all that survived.

    • Re:Puzzling (Score:4, Informative)

      by TeknoHog ( 164938 ) on Friday May 25, 2018 @06:27PM (#56676052) Homepage Journal
      Good point, but there's another issue with large insects; they need a higher concentration of oxygen in the air than what we currently have. Insects have no lungs or blood, they breathe directly into every cell, so they are more sensitive to this. O2 concentration also affects other species in different ways, many things will simply burn out with too much of it.
      • by pubwvj ( 1045960 )

        I like your little quote 'The opposite of "moron" is "lesson"' but there is a third option, 'the opposite of "Anon" is "moron"'.

      • how large is "large"? we still have 24" walking sticks and foot-wide butterflies and 7" titan beetles. wasn't the largest ever with two foot wingspan?

    • Re: (Score:2, Interesting)

      by Anonymous Coward

      According to some estimates that fallen debris may have heated the air to the temperature of a pizza oven. The ground dwelling birds and small mammals would have needed only 30-40 cm of ground to protect themselves from it. Also, animals capable of diving would have access to food supplies that had been protected from the heat and the resulting fires.
      Crocodiles and turtles can survive longer periods without food than the bigger, presumably warm blooded dinosaurs and those aquatic species may have be

    • Re:Puzzling (Score:4, Informative)

      by knorthern knight ( 513660 ) on Saturday May 26, 2018 @12:36AM (#56677076)

      > Never understood how birds are the only remaining dinosaurs... wonder what
      > made dinos so vulnerable to this event, where many other large species (crocs,
      > turtles, fish, etc) survive to this day. One might think that some ***SMALL DINOSAURS***,
      > or aquatic/marine species would have found a niche on some continent.

      By "dinos", I assume you mean umpteen ton monstrosities. Most, if not all Cretaceous dinosaurs (even the large monstrosities) are now believd to have had feathers to maintain body tempearures. Birds == dinosaurs. It's not just the newer finds. Careful re-examination shows compsognathus == archeopteryx.

      The big rock hits earth 65,000,000 years ago, and throws up a shower of debris out of the atmosphere. As the debris rains down all over planet earth, atmospheric friction heats up the incoming debris to several hundred degrees. This hail of red hot stones kills most large animals, and set most forests on fire.

      Smaller particles remain in the atmosphere for a few years, blocking a lot of sunlight, and a "nuclear winter" happens. The bottom of the ecosystem (plants) gets greatly reduced. Forget large trees; you're down to hardy ferns Any large vegetarians that survived the initial "rain of fire" die of starvation, since they need a lot of plant matter every day to survive, let alone grow. When the remaining large vegetarians starve to death, there's no food for the large carnivores, so they starve to death.

      Re your question about "small dinosaurs"... yes, some did survive. I repeat... birds == dinosaurs. The ones that survived were in the same size range as small mammals that survived. They occupied similar niches, and may have occupied burrows. If they couldn't dig burrows, they could chase out the small mammals who originally dug them. So when the big rock hit, small mammals and small dinosaurs (i.e. birds) that lived in burrows would've survived the initial "rain of fire". Burrows would be crucial for birds, because they lay eggs, rather than bearing their young via pregnancy.

      Small dinosaurs ("birds") would compete in the same niches as small mammals, and we know that small mammals survived. Surviving birds at that time would probably be omnivores. They could eat small plants, with the occasional addition of meat in the form of insects and small mammals and even other birds.

  • Alphas (Score:5, Interesting)

    by Tablizer ( 95088 ) on Friday May 25, 2018 @05:43PM (#56675858) Journal

    It's interesting that flightless birds had a pretty strong reign during the early recovery phases. They were often the dominant hunters of the time.

    It's often speculated that mammals eventually replaced those giant flightless birds as the alpha hunters not because mammals are more powerful than big birds, but rather because mammals learned to better leverage pack hunting: social coordination. Otherwise, this era would have resembled Dinosaurs 2.0, with 40-foot birds: Sqaaawwwk!! BOOOM

    • It's interesting that flightless birds had a pretty strong reign during the early recovery phases.

      By "interesting", I assume you mean "unsurprising", eh? It's not like the non-avian dinosaurs (flightless birds) didn't have a strong reign 200-odd megayears leading up to the Big Falling Rock....

      • Lighten up, this is a place for all discussion
      • by dryeo ( 100693 )

        Yes, and before that the Therapsids (our ancestors) had a good run as the dominant type of animal, until the Permian–Triassic extinction event wiped most of them (and most everything else) out and allowed the accession of the Dinosaurs.
        The birds did recover fast before being passed by mammals as the apex hunters.

    • with 40-foot birds:

      "North Perry Tower, Bonanza 1701 Sierra Tango, request an interceptor assist from the USAF, we seem to be gripped in the talons of a bird bigger than my plane..."

      "01 Sierra Papa, North Perry Tower, do you have any firearms with you?"

      "That's a negative, North Perry, we really need that assist right now, the claws are coming in through the roof..."

      *crunch* *crumple* *Burrrrp*

      Beechraft! More Taste, More Filling! *squaaaaak!*

    • Flightless birds never evolved a way to really repurpose their front limbs. Ostriches, emus, kiwis all have vestigal wings with limited use if any. Other land vertebrates, whose front limbs hadn't become so highly specialized yet, could gradually evolve them along different paths to become good tree climbers (everything from chameleons to monkeys), or learn to dig burrows (moles), to be good swimmers (OK, penguins also managed to make good use of their front limbs in that regard, but I'm not sure if the

      • by dryeo ( 100693 )

        The terror birds repurposed their wings as daggers. They were pretty scary.
        Hmm, wiki doesn't mention the wings, so perhaps I'm wrong, still a 10 ft bird that can run fast, extend its neck when striking with its large head and hooked large beak would have been scary.
        https://en.wikipedia.org/wiki/... [wikipedia.org]

  • Effects (Score:4, Interesting)

    by burtosis ( 1124179 ) on Friday May 25, 2018 @05:44PM (#56675864)
    Not suprising as it is also thought to have created a tsunami 330 feet tall along the coasts of Texas and flordia, but as high as 2.9 miles in deep ocean. It is 12 miles deep and 93 miles in diameter. It's pretty amazing as you can date the effects in many areas by the layer of material it spread over the whole world. Good thing these giant impacts are extremely rare because if we spot it late there is jack squat we could do.
  • by eaglesrule ( 4607947 ) on Friday May 25, 2018 @05:47PM (#56675874)
    Considering how the flight of the hummingbird more resembles that of an insect [phys.org] than it does of other birds.
  • I am very very likely completely wrong, but I would speculate birds - flying birds - survived, and rapidly lost their power of flight, because it was no longer needed, because their predators were all dead.

    • I would speculate birds - flying birds - survived, and rapidly lost their power of flight, because it was no longer needed, because their predators were all dead.

      The romantic in me would like to think that even a bird, non-sentient as it is, feels the beauty in flight.

    • by careysub ( 976506 ) on Friday May 25, 2018 @06:05PM (#56675958)

      I am very very likely completely wrong, but I would speculate birds - flying birds - survived, and rapidly lost their power of flight, because it was no longer needed, because their predators were all dead.

      That is very likely to have happened in any area that really lost all or most ground predators. It is the reason that flightless birds evolved in New Zealand and islands around the world. Although flightless birds have evolved on continents as well, their distribution on islands is notable, a large fraction of all flightless species hale from predator-free islands.

  • They had to learn how to fall.

  • by erice ( 13380 ) on Friday May 25, 2018 @06:38PM (#56676080) Homepage

    Both the article and the summary but not the actual paper make the claim that the only birds to survive were flightless. The actual paper talks about the demise of arboreal species. This makes sense as it is difficult for a tree-dwelling species to survive if the trees have gone. It does not follow that the survivors were necessarily flightless. Today most ground-dwelling species retain the ability to fly. And many of these have long, sturdy legs. Given that these kinds of birds don't tend to fly much, it is reasonable that many of these would adapt to a purely flightless lifestyle in the absence of predation. It does not follow that birds had to learn to fly all over again. Even if it took hundreds to thousands of years for the forests to recover, there should still be populations that retain flight ability allowing them to radiate back into the trees quickly.

    • by Anonymous Coward

      erice pointed out:

      Both the article and the summary but not the actual paper make the claim that the only birds to survive were flightless. The actual paper talks about the demise of arboreal species. This makes sense as it is difficult for a tree-dwelling species to survive if the trees have gone. It does not follow that the survivors were necessarily flightless. Today most ground-dwelling species retain the ability to fly. And many of these have long, sturdy legs. Given that these kinds of birds don't tend to fly much, it is reasonable that many of these would adapt to a purely flightless lifestyle in the absence of predation. It does not follow that birds had to learn to fly all over again. Even if it took hundreds to thousands of years for the forests to recover, there should still be populations that retain flight ability allowing them to radiate back into the trees quickly.

      If you were not already modded to +5 Informative, I'd've given you +1 Insightful for the above observation.

      The Guardian's very brief summary was obviously written by a journalist who did not understand the paper on which he was reporting. Like you, I actually read the thing. As is typical of scientific papers on paleontological hypotheses, it's pretty careful about constraining its conclusions to what the actual evidence suggests. It was The Guardian's reporter who jumped to the conclusion

  • They didn't learn too well..

  • "hundreds or thousands" of years to recover? what does recover mean? it takes forests decades to recover if that. it would take hundreds or thousands of years only for forests to recover to the exact state they were in when the fire occurred but that's a pretty nonsensical definition because some forests would _never_ recover. words, the cause of and cure to so much misunderstanding.

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