Dinosaur names often have a majestic ring to them: King of the Tyrant Lizards, Swift Seizer, Colossal Iguana. The very first scientific dinosaur name was assigned to a one-ton carnivore that likely ran about on two legs like Tyrannosaurus Rex. And what was the first bone of this great beast named after? Balls.
Let's be fair to Richard Brookes, the physician who coined the name Scrotum humanum in 1763. He had no idea he was describing a dinosaur; in fact, Sir Richard Owen wouldn't coin the word "dinosauria" until the 19th century. A fossilized bone fragment of this particular dino was discovered in a limestone quarry in Oxfordshire, England in 1676. Richard Plot, Professor of Chemistry at the University of Oxford, realized that the bone, which he correctly identified as part of a femur, was too large to belong to any known animal. Plot, describing the bone in his Natural History of Oxfordshire, believed that it must have come from a Biblical human giant. Brookes would redescribe the specimen 90 years later based on Plot's drawing which did, in all honesty, look like a pair of human testicles.
Eventually, the prehistoric owner of the femur bone would get a far more dignified name: Megalosaurus. (Try to make that dirty...oh wait...poor dinosaur.) In fact, Megalosaurus was the first dinosaur to be described and named, by William Buckland in 1824. Still, because the first name every given to the dinosaur was Scrotum humanum—even though it was given just to the femur bone—geologist Bill Sarjeant and paleontologist Beverly Halstead argued that Brookes' name should take priority over Buckland's. The International Commission for Zoological Nomenclature ruled against them, saving Megalosaurus from the indignity of its original testicular name.
Balls.
Images from Wikimedia Commons.
Jackson, Patrick Wyse, The Chronologers' Quest: The Search for the Age of the Earth [Google Books via mental_floss]