T. rex or T. anorex?

Rebecca C. Jernigan, rebecca.jernigan@laurin.com

The skeletal remains of dinosaurs capture the imaginations of young and old alike. We gaze on these creatures, so different and yet so similar to the animals we are used to, and imagine what they would have looked like in the flesh. Artists have created sketch renderings, animators have brought to life their concepts – and now scientists have applied laser imaging and computer modeling to reveal the probable weight ranges of these mysterious beasts.

The scientists created their best estimated reconstructions of a T. rex (top) and Struthiomimus sedens (bottom).

Researchers at the University of Manchester in the UK reconstructed the bodies of five non-avian dinosaurs, including two T. rex, an Acrocanthosaurus atokensis, a Struthiomimus sedens and an Edmontosaurus annectens. They scanned the skeletons with lidar and used the information to create a three-dimensional computer model. The scientists estimated the sizes of the animals’ internal organs, muscles and fat, adding them to the models.

They then varied the volumes of the body segments and the respiratory organs to find the widest reasonable range of mass for each creature. The largest of the fossils, a T. rex named Stan, from the Manchester Museum, could have weighed as much as 8 tons. The smallest, the Struthiomimus sedens or “ostrich mimic,” probably weighed between 0.4 and 0.6 tons.

As shown to the left, lidar imaging (a) enabled scientists to create three-dimensional computer models (b) of five dinosaurs, including this T. rex. They then estimated what the animals would have looked like by manipulating the models (c). Images courtesy of PLoS ONE.

In addition to estimating the weight of extinct animals, the scientists used these models to calculate the body segment masses, centers of mass and moments of inertia for each of these dinosaurs. This information could be used to analyze the way they would have moved.