February 19, 2009
We all know dinosaurs were big, but how massive were they, exactly? A complete skeleton can give scientists a good idea of the height, length, and general size of a dinosaur, but figuring out the mass carried by those skeletal frames has been a difficult question to answer. A study just published in the journal PLoS, though, applies a new technique to this quandary.
Using LiDar scanning techniques, researchers from the University of Manchester created virtual three-dimensional models of the dinosaurs Tyrannosaurus, Acrocanthosaurus, Struthiomimus, and Edmontosaurus. This not only digitally preserved the skeletons, but it also allowed researchers to play with the skeletons on the computer without risking damage to any of the precious fossils. In addition, this approach allowed the scientists to retain the appropriate scale for each skeleton–in the past, paleontologists have had to use scale models due to the impracticality of building and running tests on life-size dinosaur reproductions. This way the scientists could test different scenarios on different models, inserting air sacs and changing various aspects of the model to see what would happen. Doing the same with a life-sized mock up of Tyrannosaurus would be difficult and dangerous.
So what did the scientists find? By playing with different muscle arrangements, they found that the weights of the dinosaurs were often similar to what other researchers had determined using older methods. Even so, there was some variability in the new models that left room for different interpretations. There was no one set mass arrived at for any dinosaur –the researchers could make their dinosaurs skinny or chunky, and because many dinosaurs had holes for air sacs that lightened their bones, determining a definitive mass for a single dinosaur was complicated. What was more consistent across the different models was the placement of the center of mass of the animal: in front of and below the hips. This might seem like a minor point but it is important for reconstructing how dinosaurs might have moved and how fast they could have run.
There is a lot to dig into in the new paper (especially if you like crunching numbers), but it reflects how technology is being used to gain a better understanding of dinosaurs. Field work can be exciting, but once the bones are back in the lab, paleontologists are using all sorts of new techniques to get a closer look at the lives of dinosaurs than was possible before.
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