Science News – Teenage T. rex

Two small Tyrannosaurus skeletons, named Jane and Petey, were recently studied after being excavated in Montana nearly 20 years ago. When paleontology was just a budding, new science, smaller dinosaur fossils like these were often neglected because most museums and collectors wanted the biggest, most impressive-looking dinosaurs (see my article about Marsh and Cope). This was a big mistake because juvenile dinosaurs are smaller, but we can gather a lot of clues about how each dinosaur lived and grew from their juveniles.

To study the growth patterns of dinosaurs, paleontologists cut out a very thin slice of bone to study under the microscope. In museums, the place where they took the slice out is filled in with a replica piece. Looking under a microscope, you can see growth rings, much like growth rings on a tree. By counting their growth rings, this team of researchers determined that the T. rex Jane was probably around 13 and Petey was about 15. Of course, this is assuming that our current understanding of how to count the rings is accurate.  One interesting thing about the growth rings is that they varied in size quite a bit. This team thinks that perhaps these creatures grew more in years when food was more available and less when food was more challenging to find.

References:

January 1, 2020

Holly N. Woodward, Katie Tremaine, Scott A. Williams, Lindsay E. Zanno, John R. Horner, Nathan Myhrvold. Growing up Tyrannosaurus rex: Osteohistology refutes the pygmy “Nanotyrannus” and supports ontogenetic niche partitioning in juvenile Tyrannosaurus. Science Advances, 2020; 6 (1): 10.1126/sciadv.aax6250

Oklahoma State University Center for Health Sciences. (2020, January 1). Researchers learn more about teen-age T. rex: How the large predator grew up. ScienceDaily. Retrieved February 4, 2020 from www.sciencedaily.com/releases/2020/01/200101144031.htm