Did the Mesozoic atmosphere constrain sauropod size?

[Halichoeres]

Spoiler: probably not. It was thought once that higher carbon concentration in the atmosphere during the Mesozoic helped make sauropods huge (and arthropods, during the even warmer Late Paleozoic). This doesn't seem to be true, but many modern plants, under high carbon conditions, have a lower nitrogen content per unit mass. This study suggests that this is less true outside of angiosperms. They grew a bunch of plants under conditions corresponding to the Jurassic and then measured carbon and nitrogen contents, using the results to estimate how much usable energy they'd get as a function of how much they ate for various possible metabolic rates. Interesting study!



Open access (at least for me): https://onlinelibrary.wiley.com/doi/full/10.1111/pala.12385