Study: Dinosaurs "Shrank" Regularly To Become Birds

An anonymous reader writes A new study suggests that large dinosaurs shrunk to small birds to survive over a period of around 50 million years. Aside from a few large species, most modern birds are predominantly tiny and look nothing at all like their prehistoric meat-eating ancestors. The evolutionary process that governed this transformation has not been well understood, but now researchers from the University of Adelaide in Australia have put together a detailed family tree mapping the evolution of therapod dinosaurs to the agile flying birds we see today. Their results indicated that meat-eating dinosaurs underwent several distinct periods of miniaturization over the last 50 million years which took them down from an average weight of 163kg to just 0.8kg before finally becoming modern birds.

Comments

Smile

[nospam007]

Think of it as evolution in action.

Re:Smile

[Confusador]

You're not feeding a religious troll, you're feeding a racist troll.

Re:Smile

[StripedCow]

Actually, because of the expansion of space-time, the dinosaurs stayed the same size.

Makes Perfect Sense

[rmdingler]

In times of extraordinary resources, an ecosystem's offspring are afforded the opportunity to grow larger, and larger is often a breeding advantage.

In times of constriction of resources, those life forms with the minimal caloric needs tend to flourish.

What a beautiful and strange World it must have been in the dinosaurs heyday to support a seven ton carnivore and a 50,000 to 100,000 kilo plant eater.

Re:Makes Perfect Sense

[Arker]

"There was a lot more oxygen in the air back then. It wasn't just hotter. With the lower oxygen levels the huge dinos wouldn't do so well because they didn't have muscles for breathing like we do."

I think you are rather badly mistaken. There was actually much less oxygen in the atmosphere then.

Warning, link is not really a webpage, js required :( but you can search yourself for a better source.

Re:Makes Perfect Sense

[Artifakt]

There's also the argument that wings evolved from smaller structures which were held angled down to in turn hold the running bipod proto-bird (or advanced dinosaur) down when making sharp turns at high speeds (like automotive spoilers) . Strange as that idea sounds, if this actually worked, then it helps explain what's otherwise a pretty large gap - evolving flight. Arms races, as this one where the predators would be trying to outcorner their fleeing prey, and the prey would be trying to evade ever more agile predators, are often considered as explanations for complex evolutionary paths, and may well be true in this case, but it also means we would have an even harder time matching feathers to any specific climate data - as we don't know whether insualtion was the major advantage of the structures just because the animal didn't have the wing surface for actual flight..

No no no.

[Anonymous Coward]

First of all, Dinasours never existed. The fossils were put there by Satan.

Now, since birds are claimed to be dinasours one can only come to the conclusion that birds do not in fact exist.

The data is there to prove it. The only point where you and I disagree is how that data is interpreted and since I have the Word of the Lord, it is obvious that I am right.

Re:No no no.

[ArcadeMan]

Wrong. The noodley appendage is a make-believe idea put in our heads by the Invisible Pink Unicorn to test our faith in her.

Re:No no no.

[mark-t]

Please.

Pastafarianism is readily historically verifiable as being deliberately conceived of as a fake religion for the express purpose of satirizing other religious beliefs, not so much to mock those specific beliefs, but to actually show how ludicrous it is to use science classes in school to teach scientifically unverifiable stories about the origin of mankind, arguing that the Flying Spaghetti Monster story has exactly as much scientifically credible as any other unverifiable account of the origin of mankind (which is a mostly accurate assessment, the only difference that I can think of being that how the story of the FSM came about, and the entire purpose of its existence, to mock the teaching of Intelligent Design in schools, is very well historically documented, so the comparison isn't valid 100%... but it's close).

So if you are going to lay claim to any kind of sincere belief in a religion, you should probably try picking one whose origins are lost in obscurity by the passage of time, or at least pick one where there isn't an abundance of documentation to show that the originator only invented it to mock a specific idea, not as something that anyone should necessarily seriously believe in.

Re:No no no.

[Boronx]

Please. That origin story was put there by Satan to test our faith. You don't really believe it was all made up, do you?

Penguins Came from Whence?

[flyneye]

I wanna see the armor plated Tyrannopenguin.

Re:Penguins Came from Whence?

[Tablizer]

I wanna see the armor plated Tyrannopenguin.

http://i.imgur.com/Tkhwh.jpg

The Red Queen

[NoNonAlphaCharsHere]

I'm sorry, birds are the showiest class on the planet. Any theory about how they went from ~160Kg to ~1Kg in (only) 50 million years needs to have a healthy dose of sexual arms race to be plausible.

Re: The Red Queen

[Artifakt]

Does sexual selection actually work at all? Less controversially, does it accomplish anything regular natural selection can't, or is is an explanation that is simply redundant to natural selection as a whole?
          For example, there are some species, such as Walruses, where there are extreme differences between males and females, and we use Sexual Selection to explain how those evolved. The problem with that is revealed by Bighorn Sheep, among various other species. There, we have both a lot of dimorphism, and males acting very competitively in displaying themselves for the female, but it turns out that the famales aren't 'selecting right'. Female Bighorns seem to go off with the loser as often as the winner, or sometimes take up with a mate who isn't engaging in the head butting displays at all. Unlike Walruses, the males don't seem to have any way to keep females in a harem unless they can be convinced voluntarily, and since all a sheep has to do to signal unwillingness to mate is stop standing perfectly still, opting out seems to be the female's choice. Most recent studies either show no real pressure at all or a rather mild form of selectivity that doesn't seem like it's enough to explain major size and feature difference unless they could also be explained by non-sexual selection pressures. In other words, winning at head butting doesn't really seem to increase a male's chance of mating, so it's now unclear both why males butt heads, AND whether there as been any sex-based selection, at least in sheep, to cause the behavior.
            Something like this also shows up in African lions, where the male's size and mane can probably be explained by them being the part of the tribe that fights off Hyenas and Baboons just as well as sex based selection.

Dinosaurs went obsolete

[Anonymous Coward]

Because of the square cube law, gigantism is energetically expensive. The bigger an animal gets, the heavier it gets (disproportionately), and the more energy it needs to move. But size is relatively easy to tweak genetically, so making animals bigger to out compete their mating or territorial/predatory rivals must have been a solution which evolution hit on pretty quickly. But then evolution moved on, developing more sophisticated technology like feathers, hollow bones, and more powerful brains which could support flight and cooperative pack hunting, and gigantism became a relatively more expensive and less useful trait. Huge dinosaurs disappeared, for the same reason huge battleships did. Put a t-Rex into a forest with a pride of hungry lions. How long do you think the Rex would last?

- Tristan

Re:Dinosaurs went obsolete

[ArcadeMan]

Put a t-Rex into a forest with a pride of hungry lions. How long do you think the Rex would last?

What do you mean? An African or European tyrannosaurus rex?

Re:Dinosaurs went obsolete

[techno-vampire]

Huge dinosaurs disappeared, for the same reason huge battleships did.

Wrong. Battleships were so big because they needed to be to carry what was then the most effective weapon available: high-caliber, long-range gunnery. By the end of WWII they had been rendered obsolete by the development of effective naval aviation, carried on aircraft carriers that are even bigger than battleships were.

Re:Dinosaurs went obsolete

[Vitriol Angst]

The T-Rex would go extinct after only 50 years if all it had to eat was lions.

Unless of course someone raised a lot of lions to keep feeding T-Rex's. Or maybe T-Rex might think it was really cute how a kitty was chewing on it's bunions -- that tickles.

Re:Dinosaurs went obsolete

[gwolf]

Do you mean Laurassian or Gondwanan tyrannosaurus rex?

Bad phrasing

[twistedcubic]

This is evolution. The dinosaurs did not "shrink". The smaller dinosaurs within a species had a higher survival rate.

Re:Bad phrasing

[disposable60]

Haven't you encountered a frightening number of ID idiots who insist - often a top volume - my grandaddy warn't no MONKEY!
Your observation is true, but given the sheer number of people proud to be ignorant, not super useful.
For their benefit - and thus, ours - we gotta watch that flippant phrasing.
As the environment changed, dinosaurs evolve to be smaller, and eventually into birds.
Not catchy, but easier to defend.

Re:ORLY?

[tomhath]

And watch a chicken when it catches a mouse. Vicious carnivore will cross your mind.

Re:Interesting question...

[khallow]

I believe the current WAG is that the earliest environments were free-fire chemical zones with molecules or perhaps groups of molecules prey on others. Anything you could throw in the way of a hostile molecule, such as a lump of protein or a sliver of calcium carbonate, improved your odds of survival. Later those obstacles became a wall of an organelle or bacterium and the interior a nice place for cooperative molecules to get to work. Some sort of arms race happened and some organelles became cells that incorporated other organelles. Then multi-celled life and photosynthesis happened and the neighborhood just went to hell.

Re:OT: this stuff was solved in the 90's

[rubycodez]

haven't you heard, all the slashdot intelligentsia made a mass exodus to kuro5hin.org

In my head

[Chas]

*ROAR!*

T-Rex: "See! THAT'S how you do it! Make sure they can't run because they've just packed those "pants" things with a fear-spawned self-crapping! Now you try!"

*CHEEP!*

Hummingbird: "How'd I do? He still looks terrified. But I can't tell if that's me or you!"

T-Rex: *SNIGGER* "Oh! It's you!" *SNERK* "Definitely you!"

Obligatory XKCD

[stoborrobots]

http://xkcd.com/1211/ This is a good world....

Comment removed

[account_deleted]

Comment removed based on user account deletion