• Tag Archives gigantothermy

  • Dinosaur eggshells prove that dinosaurs weren’t molluscs.

    Posted on by Jura Comment
    Chicken egg lit up using the candling method. Image from backyarchickens.com

    This week saw the release of a new paper that has implications for dinosaur metabolism.

    Dawson, R.R., Field, D.J., Hull, P.M., Zelenitsky, D.K., Therrien, F., Affek, H.P. 2020. Eggshell Geochemistry Reveals Ancestral Metabolic Thermoregulation in Dinosauria. Sci. Adv. 6:eaax9361. (Open Access)

    The paper makes some pretty hefty claims regarding dinosaur metabolism, and as such, has received a fair share of media coverage touting this as the latest evidence for “warm-blooded” (i.e., automatic endothermic) dinosaurs.

    Every time there is a major headline like that, I feel obliged to go back to the source to see what the media has likely overblown. In this case, media claims don’t seem that far off what was written in the actual paper, which is not necessarily good. Some of these claims do extend beyond the reach of the available evidence (e.g., there actually is no comparison with other contemporaneous reptiles of the region, weakening any arguments for metabolic thermoregulation).

    It’s been an age since I’ve done one of these paper breakdowns, but I think this one warrants a more thorough analysis, especially given the implications of the interpretations.

    Continue reading → Post ID 3571


    This entry was posted in Dinosaurs Extinct Reptiles Uncategorized and tagged

  • T-U-R-T-L-E Power Part 3: Leatherbacks Break All the Rules.

    Posted on by Jura 3 Comments
    Leatherbacks are already viewed as unique, but you might be surprised at just how strange this species really is. Picture from: amigosdomarnaescola.com

    Continuing the series, let us now take a look at one weird turtle species in particular: Dermochelys coriacea, the leatherback sea turtle.

    While the utter weirdness of D.coriacea is ultimately the main reason for why it wound up in this series, there is an ulterior motive. Having searched the internet for general information on the species I found myself rather disappointed with the amount of utterly generic / wrong info regarding leatherbacks. Its Wikipedia entry is particularly disappointing. So here’s hoping this influx of information can help alleviate that.

    A turtle without a shell?

    Yes, it’s true, leatherback turtles have lost their shells. Shell reduction is relatively common in turtles. It seems a little funny. After going through all the trouble of evolving impregnable armour, many taxa then went out and removed large chunks of it. We see shell reduction in snapping turtles (Chelydra and Macrochelys), soft-shelled turtles, and even other sea turtles. None of them, however, reduced their shells to the point of actually removing them.

    In leatherbacks the “shell” is nothing more than a loose collection of osteoderms spread over the back and belly. There is no longer a definitive carapace, or plastron. In fact leatherbacks don’t even produce Beta-keratin (the hard component of reptile scales). Instead this has all been replaced by thick, leathery skin.

    Continue reading → Post ID 3571


    This entry was posted in Chelonia Extant Reptiles Uncategorized and tagged