Lack of females may have done in dinosaurs, says study

Reuters ^ | Thursday, April 22, 2004 | Reuters

[Einigkeit_Recht_Freiheit]

WASHINGTON — An asteroid may have wiped out the dinosaurs 65 million years ago not simply by changing the world's climate and causing years of dark skies but also by causing too many of them to be born male, U.S. and British researchers said this week.

If dinosaurs were like modern-day reptiles such as crocodiles, they change sex based on temperature, said David Miller of the University of Leeds in Britain and colleagues. And even a small skewing of populations toward males would have led to eventual extinction.

Most experts agree that one or more asteroid impacts probably triggered a series of global changes that killed off the dinosaurs and many other species of life on Earth. The impacts would have kicked up dust that cooled the air and also triggered volcanic activity that would have created even more dust and ash.

No one really knows if dinosaurs were more like reptiles or something closer to mammals. Reptiles have very different metabolisms than mammals and also have various ways of determining the sex of offspring.

In mammals, if a baby gets an X and a Y chromosome, it will be male, and if it gets two X chromosomes it will be female, with a few very rare exceptions. Similar mechanisms work for birds, snakes, and some reptiles such as lizards.

But in crocodilians, turtles, and some fish, the temperature at which eggs are incubated can affect the sex of the developing babies.

Miller's team ran an analysis that showed a temperature shift could theoretically have led to a preponderance of males. Other studies have shown that when there are too few females, eventually the population dies out.

"The Earth did not become so toxic that life died out 65 million years ago; the temperature just changed, and these great beasts had not evolved a genetic mechanism (like our Y chromosome) to cope with that," said Dr. Sherman Silber, an infertility expert in St. Louis who worked on the study.

But crocodiles and turtles had already evolved at the time of the great extinction 65 million years ago. How did they survive?

"These animals live at the intersection of aquatic and terrestrial environments, in estuarine waters and river beds, which might have afforded some protection against the more extreme effects of environmental change, hence giving them more time to adapt," the researchers wrote.

[Einigkeit_Recht_Freiheit]

This is just fascinating and really a bit obvious, although I never heard it before.

Also makes me wonder if the Chinese, due to their 1 child policy and the tendency to abort or kill females will eventually suffer the same fate.

[woofie]

were dinosaurs gay?

[swilhelm73]

Other studies have shown that when there are too few females, eventually the population dies out.

Your tax dollars at work folks...

[AntiGuv]

They may've been there in the end.. Some reptiles and amphibians switch sexes or turn homosexual en masse when the climate throws off the biological rhythms they've adapted.

[Ichneumon]

Already posted here with 77 replies.

[Junior]

Already posted here.

[Fresh Wind]

were dinosaurs gay?

Only the purple ones.

[Drango]

I blame Bush....

[AntiGuv]

As well you should! :p

[billorites]

[Oldeconomybuyer]

...Other studies have shown that when there are too few females, eventually the population dies out...

I wonder if these "other studies" were done in San Francisco...

[rintense]

And this is why nature made the praying mantis. ;)

You know, I thought of the Chinese too. There was an article not too long ago about the overwhelming lack of women in China by the year 2025.

[kissmyconservativebutt]

See!!!! Being gay does wipe out a species!!! If we allow gay marriage we will become extinct!!!

[Onelifetogive]

Lack of females may have done in dinosaurs, says study.

And T. Rex with those short little useless arms and hand. No wonder he was so angry......

[underbyte]

If all dinosaurs were birds (as they been saying for awhile) Then temperatures would make no diff.

[oceanperch]

Well with all the hoopla coming from the Homosexual/pedaphiliacs if the Earth gets his by a giant meteorite we will know why.

Maybe the meteor that just cruised by the sun in reports earlier this week was a hint.

[skinkinthegrass]

Were dinosaurs gay?...Only the purple ones.

HA! HA!...LOL! :)