Quote:
Originally Posted by AstralTraveller
Carl, there are no other techniques for determining a dinosaurs' body temperature. In fact there is no other method to determine the temperature of formation of any carbonate (mineral or biogenic) without knowing some other data, which we generally don't. The temperature record derived from deep-sea cores assumes that the temperature of the deep ocean hasn't changed and isotopic composition of ocean water is also constant. This is valid for a few million years but no further. In other environments the assumption isn't even valid for a few years. For instance we cannot determine the temperature of formation of even Holocene soil carbonates because we do not know the isotopic composition of the soil water from which they precipitate. Even if we try to guess the isotopic composition of rainwater, it is then subject to an unknown amount of evaporative enrichment (water containing only the light isotopes evaporates faster than that containing heavy isotopes). This is why my boss calls it the fourth revolution in stable-isotope mass spectrometry, and why he jumped straight in!
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I know about C12/14 and O16/18 isotopic analysis...I do have degrees in geology you know
I wasn't specifically talking about the dinosaurs literal body temperature, but more about the determination as to whether they were warm or cold blooded. You can determine if an animal was either warm or cold blooded by doing a thin section of their bones...especially large ones like the femur and looking at the structure and density of the blood vessels present in them. This is also possible for fossilised creatures, such as dinosaurs, where the internal structures of the bone are preserved. Actually, it has been done on a number of species of dinosaur, though the more prominent ones have been done on T-rex. Their bones show similar internal vascular structure as a turkey's, and where they've been lucky enough to find preserved blood cells, their shapes indicate the animal was warm blooded.
The big problem with this new type of isotope determination is you're going to have to take into account how these isotopic ratios have been modified over time by diagenetic and other geological process. Even though the isotopic ratios do get fixed in the bone/shell structures of the animals when they die, those bones/shells are affected by later processes and the ratios of the isotopes that maybe present in the newly found fossils aren't necessarily the same as when the animal died, or even when it was alive. So, just how accurate are these temperature determinations going to be in the first place. What you would have to find is either wholly unaffected bone, which by chance they have found on a few rare occasions, or bone that's been preserved in a manner that's also preserved the original isotopic balance within the bones. Very unlikely, but as I have mentioned, not unheard of.
