dinosaurs may have died out because of low # of females

[bobbieinok]

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, US and British researchers say.

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

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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.

In crocodiles, turtles and some fish though, the temperature at which eggs are incubated can affect the sex of the developing babies.

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http://www.nzherald.co.nz/latestnewsstory.cfm?storyID=3561782&thesection=news&thesubsection=world

[izzie]

1. Or because they elected George Bush to run the place.

The end is near.