New Scientist
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Early birds like Archaeopteryx were far too heavy to sit on their eggs without cracking them. The conclusion holds true for non-bird dinosaurs too, leading to fresh doubts about how to interpret spectacular fossils that appear to show dinosaurs brooding their eggs.
Most birds today lay eggs with strong, hard shells. This strength is necessary because many birds practice contact incubation – meaning the adult rests its body weight directly on the eggs. But just because modern bird eggs can support the weight of a brooding adult it doesn’t necessarily follow that ancient bird eggs could, says Charles Deemingat the University of Lincoln, UK.
To investigate, Deeming and his colleague – Gerald Mayr at the Senckenberg Research Institute and Natural History Museum Frankfurt, Germany – looked at fossils of 21 species of bird that lived alongside the dinosaurs during the Jurassic and Cretaceous.
For each species, they studied the bones of pelvis and estimated the size of egg that the bird could have comfortably laid. A recent study suggests there is a predictable relationship between egg size and strength, which means Deeming and Mayr could predict what sort of load the eggs of their ancient birds could have withstood before cracking. Read more on newscientist.com…
