On the Dead Things blog at Discover Magazine, Gemma Tarlach talks about an interesting new finding in connection with fossilized dinosaur eggs (Protoceratops and Hypacrosaurus) that may indicate why most dinosaurs went extinct during the end-Cretaceous mass extinction:
Paleontologists have long thought that the incubation period for dinosaur eggs was similar to that of modern birds which are, after all, the only dinosaurs still around. Modern bird incubation periods range from a little more than a week to just under three months. Based on the von Ebner lines revealed in the new study, however, dinosaur eggs appear to have incubation periods of three to six months — a lot longer.
So what, you might be saying, because you’re a callous person who only reads dinosaur stories in hopes of hearing someone has managed to clone one (dream on, buddy!).
Well, the more time you’re sitting in an egg waiting to be born, and the more time one of your parents is sitting on you and your siblings keeping you warm, that’s time both adult and embyro [sic] are vulnerable to predation and nasty environmental surprises such as floods wiping out the nest. It’s also time lost for the parents that could have been spent rearing other young and/or prepping for the next batch o’ babies if you know what I mean.
I dunno. Without more discussion of the causation series, I don’t see how this would be a critical attribute of the extinct lines of dinosaurs; also, this is only two out of dozens and dozens of species. A great deal of speculation, so far as I can see. From the academic paper’s abstract, title of “Dinosaur incubation periods directly determined from growth-line counts in embryonic teeth show reptilian-grade development“:
Birds stand out from other egg-laying amniotes by producing relatively small numbers of large eggs with very short incubation periods (average 11–85 d). This aspect promotes high survivorship by limiting exposure to predation and environmental perturbation, allows for larger more fit young, and facilitates rapid attainment of adult size.
