FLORIDA STATE UNIVERSITY, DARLA ZELINITSKY From their warm-blooded innards to their feathered exteriors, increasing evidence shows that birds and many dinosaur species had a lot in common. But a key difference exists early in life, according to a study published January 3 in PNAS—dinosaurs had vastly longer egg incubation periods, more similar to that of modern reptiles than birds.
Gregory Erickson, a paleontologist at Florida State University, and colleagues analyzed the dental records of embryos in fossilized dinosaur eggs. By examining fine growth lines that represent daily deposits of tooth-building tissue called dentin, the researchers determined that dinosaur eggs probably took about twice as long to hatch as similarly-sized bird eggs. Protoceratops andrewsi, a horned dino, incubated their eggs for about three months, the study suggests, while the larger, duckbilled Hypacrosaurus stebingeri incubated theirs for six.
The findings may provide insight into how dinosaurs ultimately went extinct. Incubation times increase with egg size, the authors write, and Hypacrosaurus was hardly the largest dinosaur around. After a devastating event like an asteroid impact, long incubation times would have been hugely disadvantageous, hindering dinosaurs’ abilities to ...
