Friday, September 18, 2015

Dino Tootsies and the Reverend Hitchcock

Dinosaurs and birds share many things in common, and one of the most important characteristics that links the two is their feet.  Looking at the foot of a chicken and a tyrannosaur, you can see a number of fascinating similarities.  In both animals, you can see that the toe bones, the metatarsal bones, form a surface with which the tibia, astragalus, and calcaneum. This is one of the most important defining characteristics of the dinosaurs, and a fascinating link with modern birds! 
Above is a leg of a Gorgosaurus, a type of tyrannosaur that lived about ten million years prior to the famed Tyrant Lizard King. You can see the flat section at the top (or proximal) end of the fused metatarsals, and you can just see the bottom of the astragalus and calcaneum at the top of the photo. This leg is currently on display at the Denver Gem and Mineral Show, and can be rented or purchased from The Dinosaur Brokers. 

Gorgosaurus, ballet dancers, cats, penguins, and hobbits all share one thing in common: they spend a lot of time on their toes. When you walk on the balls of your feet, you are walking like a dinosaur, cat, dog, or deer. For all of these animals, the metatarsals rarely, if ever, touch the ground, and instead help to make the leg just a bit longer. Ever wonder why a flamingo's knee bends backwards? It actually doesn't, they just have an extremely long ankle!
Here's how I would walk if I was a dinosaur, dog, cat, bird, or deer....
....and here's how I would walk if I was a human, bear, or raccoon. 

During the 1800s, a man named Alfred Hitchcock was able to glean fantastic insight into dinosaur anatomy simply by studying their fossil footprints in the Connecticut River Valley. Reverend Hitchcock determined that these animals looked like modern birds, walking on their toes, and their tails held well off the ground. Some critics of Hitchcock point out that the good Reverend never actually said that his bird-like track makers were dinosaurs. At the time, however, the best scientific minds in Europe believed dinosaurs were colossal, lumbering quadrupedal behemoths, with sprawling legs, a crocodile-like gait, and mammal-like paws. No one in their right mind would have put the two together, and Hitchcock was clearly blessed with a brilliant, highly analytical mind. 
The foot of the primitive, Late Triassic dinosaur Herrerasaurus, also from The Dinosaur Brokers. Notice that, unlike the Gorgosaurus (who would live nearly 160 million years later), the metatarsal bones have undergone fusion to a much lesser degree. 

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