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

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.

Comments

Puzzling

[ztexas]

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.

Re:Puzzling

[TeknoHog]

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.

Re:Puzzling

[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 been vulnerable as their food chains were altered by the changing climate and marine chemistry from the impact and increasing pressure from the fish.

Re:Puzzling

[knorthern knight]

> 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

[Tablizer]

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

Effects

[burtosis]

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.

Re:Effects

[clotaire]

if we spot it late there is jack squat we could do.

Can we do anything if we spot it early ?

in more ways than one

[eaglesrule]

Considering how the flight of the hummingbird more resembles that of an insect than it does of other birds.

Re:Flight is lost if predators no longer exist

[careysub]

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.

Non-arboreal != flightless

[erice]

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.

Re:Chickens

[iggymanz]

chickens that aren't obese corn fed blubber balls can fly

https://www.youtube.com/watch?...