Dinosaur dads 'took care of the kids'
Carnivorous dinosaurs were doting fathers who cared for eggs of more than one female, palaeontologists claim
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Friday, 19, Dec 2008 08:29
Carnivorous dinosaurs were doting fathers who cared for eggs of more than one female, palaeontologists have claimed.
Far from the terrible lizard reputation their name suggests, new research shows that males from three types of dinosaurs were the sole care givers for their mates' eggs.
Palaeontologists from Montana State University say the behaviour mirrors that of dinosaurs' closest living relatives, birds and crocodiles.
The dinosaurs in the study were close ancestors of birds, and their fossils were found on top of unusually large clutches, said David Varricchio, an MSU palaeontologist and lead author of the paper.
Publishing his research in Science, Mr Varricchio said it was possible that the males mated with several females who laid their eggs in one large clutch. When the females left, the males incubated and protected the eggs on their own.
"Scientists have long debated which care system, male-only or both parents, evolved first," he explained.
"The new research indicates that male-only care came first, evolving within the closest dinosaur ancestors of birds."
Previous studies had found that dinosaurs shared other reproductive features with modern-day birds, including asymmetric eggs with nearly identical eggshells.
Male-only care is common among large flightless birds like emus and rheas and the South American tinamous.
To further test the theory, the palaeontologists examined the bones of adult dinosaurs found on top of clutches in Montana and Mongolia. None of the bones contained tissue normally associated with egg-laying females. Female birds store minerals for egg-laying as extra tissue in the inside of their hollow limb bones.
Co-author Greg Erickson commented: "This is important research in that it tells us about when and how an important aspect of the modern avian reproductive system came to be.
"Prior to the discovery that birds are in fact theropod dinosaurs, these animals seemed almost alien among reptiles and scientists were at a loss to explain how the modern avian condition evolved."