To kick things off with this blog I thought I’d write about some research that encapsulates so many of the things that I love about studying science – discovering beautifully simple relationships, combining different fields of research into something awesome and perhaps most of all, dinosaurs!
This story begins with research into bioapatite, a mineral component of teeth and bones that gives them their hardness. As well as containing calcium, phosphorous and a few other kinds of atoms, bioapatite contains carbon and oxygen atoms.
Like most elements in the periodic table, carbon and oxygen can be found in a number of different forms, known as isotopes, which differ in the number of neutrons that they contain. The researchers were looking at the isotopes known as Carbon-13 and Oxygen-18 and how much was in the bioapatite compared to the more common Carbon-12 and Oxygen-16 isotopes. They found that the lower the temperature when the bioapatite was formed, the more Carbon-13 and Oxygen-18 it contained.
This is a neat little discovery but you would be forgiven for thinking “So what? Why is that of any interest?” Well, the answer to that lies in how they used this information to make their next discovery.
Ever since their discovery, we have wondered if dinosaurs were cold blooded like modern day reptiles or warm blooded like birds (which evolved from dinosaurs) and mammals. As we all know, dinosaurs have long been extinct so there is no way to directly measure the temperature of one. But the bioapatite research now gave scientists a reliable thermometer and an amazing opportunity to do something previously thought impossible.
A group of scientists at Caltech were able to analyse fossilised teeth of sauropods (dinosaurs with long necks and tails and the biggest animals to ever live on land) and calculate what their average body temperature would have been. The results showed that these sauropod dinosaurs had a temperature of 35-38°C, similar to humans and other mammals and significantly warmer than their closest living reptiles, crocodiles. So does this mean that dinosaurs were warm blooded? Well, not quite.
Because the sauropods were so large they would have maintained a lot of body heat, regardless of whether they were cold or warm blooded. In fact, previous models expected them to have body temperatures of over 40°C. This means they may have had body adaptations or behaviours that helped them to lose heat.
So the question of dinosaurs being cold or warm blooded can’t be answered just yet but we do have another piece of the puzzle. The research team will now look at other prehistoric species, including smaller dinosaurs to gain more information and try to determine when warm-bloodedness first arose.
In the meantime, just appreciate how a bit of inspired questioning can turn what could be seen as boring, “so what?” knowledge into an amazing finding that we previously thought would be impossible to ever discover. That, in short, is why I love science.
Eagle, R. A., Tutken, T., Martin, T. S., Tripati, A. K., Fricke, H. C., Connely, M., et al. (2011). Dinosaur Body Temperatures Determined from Isotopic (13C-18O) Ordering in Fossil Biominerals. Science, 333, 443-445. doi: 10.1126/science.1206196
For more information, watch the video of the researchers explaining it themselves at the Caltech news release.