Did dinosaurs lack daughters?
23 April 2004 HELEN PEARSON
Dinosaurs may have been forced into extinction partly
because there were too few females, say researchers in the
UK. The claim revives a venerable debate.
The creatures died out roughly 65 million years ago, around
the time that a huge meteor slammed into earth. Some
scientists believe that the immense dust cloud thrown up
caused swings in the climate that the dinosaurs were unable
to survive.
However, it is not clear exactly how the temperature change
killed them off. Now David Miller of the University of Leeds
and his colleagues are proposing in Fertility and Sterility
that if dinosaurs used temperature to determine
of males to females.
This idea is based on the reproduction of modern day
reptiles such as
temperature at which their eggs are incubated. Male crocs
hatch in moderate temperatures, while females emerge if the
heat rises or falls by a few degrees.
In the case of dinosaurs, Miller suggests that changes in
temperature after the meteor impact favoured the birth of
males. Over time females would become rare, causing fewer
young dinosaurs to be born and species to dwindle to
extinction. "They'd probably have had it," he says.
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Comment:
offspring. But birds are thought to be strongly related to
dinosaurs, and
birds have two W chromosomes and females have a W and a Z
chromosome.)
Posted by Robert Karl Stonjek.