Dinosaur Eggs: Troodon formosus

The other day I mentioned an interesting study on dinosaur embryos, a day or so later a study on incubation strategies in Troodon was published in Paleobiology. I don’t have access to this article so I will have to rely on the the abstract and the press release on Science Daily.

Different egg-laying animals have different incubation strategies. For example, crocodiles completely bury their eggs in nesting materials, while some birds while some birds incubate their eggs in open nests. Since, based on available evidence, most dinosaurs laid eggs (unless you consider the ovoviviparous ichthyosaurs to be dinosaurs) it would be nice to know how they incubated their eggs. One way of addressing the question is to look at the eggs themselves. Eggs that are completely buried have different physiological properties from those that are partially buried or those that are incubated in an open nest. The paper looked at three traits: porosity, water vapor conductance, and shape. The research found some variation in porosity while water vapor conductance was similar to that found in extant birds and reptiles that incubate their eggs in open nests. Based on the variation in porosity and the shape of the eggs the researchers concluded that (from the abstract):

Low total conductance compares favorably to values in extant birds and non-avian reptiles that incubate in open nests, arguing against full burial incubation. Together with nesting site evidence, low conductance values favor partial burial and incubation by a Troodon adult. Asymmetric egg shape concentrates volume, surface area, and conductance near or at the point of subaerial exposure. Among non-avian dinosaurs, the eggs of Troodon and troodontids are most similar to those of modern birds in having an asymmetric shape, low porosity, no ornamentation, and three structural eggshell layers.

Below is cast of Troodon formosus eggs:
(Source)