Not So Tiny

We saw earlier this week that Ray Harryhausen made a very nice stopmotion Eohippus for the film The Valley of Gwangi. The reason that the horse was so small is that it was a common misconception that the horse was the size of a Fox Terrier. Many sources have mentioned this size issue many times, but the ultimate source appears to be, according to Stephen Jay Gould, a description of Eohippus written by Henry Fairfield Osborn. It was Gould's opinion that Osborn was excited about the idea of a horse similar in size to a dog and that he was vague in his metaphors to fox hunting when describing the small horse Eohippus. Osborn's comparisons and metaphors make Eohippus out to be a 15 in tall 19 lb horse (the size of a Fox Terrier, obviously); however, Eohippus is approximately 24 inches tall and weighed approximately 50 lbs. There is a difference in the way these animals are measured as well; dogs and horses are both measured from the ground to their withers, the caudal aspect of the shoulders; however, horses typically have a little more soft tissue (muscle and/or fat depending on the breed of dog or horse) than dogs in this area. This is only a problem in comparing the two similarly sized animals in that Eohippus is lacking in the soft tissue area; either way it is still taller than a Fox Terrier. Unfortunately, this sizeable lie is the largest claim to fame, for most people, for Eohippus. It was, of course, also the first recognizable horse, making it an important fossil animal in the history of not only horses, but human beings and, arguably, a large portion of the globe and all of its life. For those more interested in the impact that the descendants of Eohippus have had on the world I recommend starting with this article from Khan Academy.