How wide can you open your jaw? Typically humans can open their jaw around 50 mm, with sex and height affecting this a bit. Recently Dr. Stephan Lautenschlager at the University of Bristol has made a discovery about how far open Tyrannosaurus rex, Allosaurus fragilis (a close light-weight relative of the T-rex), and Erlikosaurus andrewsi (a herbivorous relative of the T-rex) can open their jaws, and the results reminds us that our jaws are functionally designed to meet the daily demands we put on them.
Typically carnivores have larger and wider mouths than herbivores. This is partly the dimensions of the jaws, but it’s also the way the muscles are designed to function. Dr. Lautenschlager was curious to see if this was the case with larger theropod dinosaurs (such as T-rex). In order to test this hypothesis Dr. Lautenschlager took detailed computer models of these three dinosaurs and opened and closed their jaws with special attention paid to strain on the digital muscles along the jaw. He then compared this data to living relatives (such as crocodiles and birds) and was able to draw conclusions.
The carnivorous dinosaurs (Tyrannosaurus rex and Allosaurus fragilis) had jaws that extended to nearly 90 degrees, doubling the 45 degree maximum that the herbivorous Erlikosaurus andrewsi was capable of. The opening in the mouth for a large T-rex would have been more than five feet!
This makes sense when you reflect on the fact that T-rex have humongous teeth which are specialized for cutting and crushing. Trying to chew huge chunks of flesh with a mouth that can only open 45 degrees would likely result in serious jaw injuries. Instead, T-rex’s jaws were designed to open wide and to deliver massive amounts of force through its entire arc of motion.
It should go without saying that humans should not try to open their mouths 90 degrees. Despite what some paleo diet advocates might have you believe, our jaws aren’t really designed for stripping huge hunks of meat off the flank of a mastodon. Instead, they’re designed to provide maximum function for a number of complex demands, ranging from strenuous grinding of tough leaves to delicate motions suited for speech. This makes the temporomandibular joint extremely flexible, but also vulnerable to injury.
As previously mentioned, the average adult human can only open their mouths 50 mm, but some people can’t manage even that without pain. If you are having difficulty opening your jaw, you may have lockjaw. And watch out for popping and clicking, as these can be early warning signs that you have TMJ which can later develop into lockjaw. If you are in the Spokane or Spokane Valley area and are in need of a TMJ dentist who is well versed in treatments for lockjaw, please call Collins Dentistry and Aesthetics at [lct_tel_link phone=”(509) 532-1111″] [Spokane] or [lct_tel_link phone=”(509) 927-2273″] [Spokane Valley] .