News24

Dinosaurs 'put eggs in wrong basket'

2012-04-18 12:24

Paris - The fact that land-bound dinosaurs laid eggs is what sealed their fate of mass extinction millions of years ago while live birthing mammals went on to thrive, scientists said on Wednesday.

In a new explanation for mammals' evolutionary victory over dinosaurs, researchers said a mathematical model has shown that infant size was the clincher.

Given physical limitations to egg size, dinosaurs had comparatively small young. Some came out of the egg weighing as little as 2-10kg, yet had to bulk up to a hefty 30 or 50 tons.

Growing up, the youngsters had to compete in several size categories with adults of other animal groups for food, University of Zurich scientist Marcus Clauss told AFP.

This meant that all the small and medium animal size categories supported by the natural environment were "occupied", leaving no room for smaller dinosaur species in which to thrive, according to the findings published in Biology Letters, a journal of Britain's Royal Society.

"There is a lot of room in the ecosystem for small species, but [in such a scenario] that room is taken up by the young ones of the large species," Clauss explained.

"That was not a problem for 150 million years but as soon as something happens that takes away all the large species so that only small species remain, if there are no small species to remain you are gone as a whole group."

The catastrophic event that wiped out all larger life forms some 65 million years ago meant the end for terrestrial dinosaurs.

Mass extinction


Scientists disagree on whether the scaly reptiles died out before or after a meteorite smashed into Earth in what is known as the Cretaceous-Tertiary impact, causing billions of tonnes of wind-borne ash and dust to filter out light from the Sun and triggering a "nuclear winter" that cooled the planet and withered vegetation.

Mammals did not have the same limitations in size spread, said Clauss, because their young were not born as comparatively small and did not need to compete with other species for food, instead suckling on their mothers.

This meant there were smaller mammal species able to cope with the new post-catastrophe environment and evolve into new species alongside birds, which are also dinosaurs.

"The question that haunted some people including me is ... why did the mammals survive and why did the dinosaurs not. I think we have a very good answer for that," Clauss said.

The researchers said egg size is constricted by upper limits to the thickness of shells, which have to allow oxygen through to the embryo.

The average four-ton titanosaur, the largest type of vertebrate that ever lived, was 2 500 times heavier than its newborn. A modern-day elephant mother weighs 22 times more than her calf.

Scientists say all animals with a bodyweight of more than about 10-25kg died in the mass extinction event.

Comments
  • Shaun - 2012-04-18 13:29

    Theres that magic number.... Miiiiillllllllllllllionnnnnsssss of years... Like Im supposed to sit here in awe.... Pfffft... Silly evolutionists, the law of angular momentum proves your entire silly theory wrong.... Here is another theory and in my opinion waaaaay more likely to have happened, Dinosaurs lived with man in the garden of Eden, one day the fountains of the deep and the heavens erupted and drowned everything, one family survived, this family took two of each kind of animal, not species, but kind of which there are rougly 8000, being smart they realised take babies not adults of each species, babies eat less, sleep more and are tougher, DUH..... Including dinosaurs, but dinosaurs having nostrils the same size as a horse could not survive in the new climate and decreased air pressure... Coupled with being hunted because no one wants to live with a "dragon" next door makes repopulating the entire dinosaur species really difficult.... Just saying....

      Mike - 2012-04-18 13:51

      Shaun you are probably the most stupid person ever to post with Dumbwin. Are you now an expert on paleontology, please cite your academics achievements ! The absolute rubbish you post, have you no shame at the complete fool you make of yourself daily!

      Mike - 2012-04-18 13:51

      Shaun you are probably the most stupid person ever to post with Dumbwin. Are you now an expert on paleontology, please cite your academics achievements ! The absolute rubbish you post, have you no shame at the complete fool you make of yourself daily!

      Bram - 2012-04-18 13:53

      You're an idiot

      Bram - 2012-04-18 13:53

      You're an idiot

      Jonathan - 2012-04-18 13:54

      Wow. How embarrassing

      Jonathan - 2012-04-18 13:54

      Wow. How embarrassing

      Raven - 2012-04-18 13:59

      Whatever you're having, I WANT SOME! Can you substanciate ANY of what you are saying? This clap is not even mentioned in the Bible - other than the Noah bit. And what happened to the ocean saurians? And babies tougher? Without being fed nearly continuesly they just, you know, sorta, DIE! I do not necissarily agree with the story above, but what you are spouting makes NO sense.

      Raven - 2012-04-18 13:59

      Whatever you're having, I WANT SOME! Can you substanciate ANY of what you are saying? This clap is not even mentioned in the Bible - other than the Noah bit. And what happened to the ocean saurians? And babies tougher? Without being fed nearly continuesly they just, you know, sorta, DIE! I do not necissarily agree with the story above, but what you are spouting makes NO sense.

      Zing - 2012-04-18 14:06

      lol Shaun - you've been watching too many Kent Hovind DVDs

      Zing - 2012-04-18 14:06

      lol Shaun - you've been watching too many Kent Hovind DVDs

      Dave - 2012-04-18 14:15

      I'm not sure if you are being serious or not, i get the feeling everyone who is throwing a hissy fit over your post is taking stuff too seriously.

      Dave - 2012-04-18 14:15

      I'm not sure if you are being serious or not, i get the feeling everyone who is throwing a hissy fit over your post is taking stuff too seriously.

      Mark - 2012-04-18 14:17

      You're an idiot

      Mark - 2012-04-18 14:17

      You're an idiot

      jody.beggs - 2012-04-18 14:19

      What a troll you are ! Damn the man.

      jody.beggs - 2012-04-18 14:19

      What a troll you are ! Damn the man.

      pieter.bosch - 2012-04-18 14:32

      Shaun your kop rasa wena!!

      pieter.bosch - 2012-04-18 14:32

      Shaun your kop rasa wena!!

      hyped989 - 2012-04-18 14:46

      oh hell... this guy again. Even worse than the last comment of his I read. That is the dumbest thing I have ever heard in my entire life. Yeah bro, that is waaaaaay more likely to have happened. Do you put out milk and cookies at christmas?

      hyped989 - 2012-04-18 14:46

      oh hell... this guy again. Even worse than the last comment of his I read. That is the dumbest thing I have ever heard in my entire life. Yeah bro, that is waaaaaay more likely to have happened. Do you put out milk and cookies at christmas?

      khumza - 2012-04-18 18:15

      Shaun you imbecile it's science & not magic. & why on earth should we care what your "opinion" is?, please man leave what you cannot comprehend to those who can and go concentrate on your magic and myths!

      khumza - 2012-04-18 18:15

      Shaun you imbecile it's science & not magic. & why on earth should we care what your "opinion" is?, please man leave what you cannot comprehend to those who can and go concentrate on your magic and myths!

      Peter - 2012-05-21 14:00

      @Shaun...I agree with you and Kent Hovind ... Its like a bed time fairy tale story starting with a long long time ago.All the dating techniques evolutionists use are suspect. The bible explains it all.

  • noChimp - 2012-04-18 17:23

    Were these scientists or drunkards that thought up this junk; what about the crocs, aligators or the Komodo dragon; why did they not go extinct? Sorry is this research or conjecture, desperately trying to find something to fit a belief system. We often cannot even figure exactly what happened at the scene of a crime or accident that happened yesterday, and we are desperately trying to explain exactly what happened supposedly 65 million years ago.

  • zane.zeiler - 2012-04-18 17:52

    Why o why do you religious zealots always come on here and spoil the science articles? Media24 should create a channel for feeble minded folk called religion24 where you and your ilk can engage each other on your favorite bible stories and your religious pseudo "science" creationism... On religion24 you can also enjoy news headlines like; "God kills 240 000 Buddhist Asians with Tsunami!" and "Jesus saves frightened kitten from tree by getting an old lady to call the fire department" You can even have monthly special report on the impending apocalypse!

      jaco.barkhuizen - 2012-04-18 20:59

      That is the funniest thing I've read in ages. But unfortunately also true.

      jaco.barkhuizen - 2012-04-18 20:59

      That is the funniest thing I've read in ages. But unfortunately also true.

      Sam - 2012-05-21 14:31

      Its called freedom of expression!

  • Garth - 2012-04-18 19:41

    Gotta love em xtian trolls.. They make me want to convert so desperately to become just like them!

  • pages:
  • 1