diplodocus (n.)

genus of long-necked, long-tailed Jurassic dinosaurs, 1884, coined in Modern Latin in 1878 by U.S. paleontologist Othniel Charles Marsh (1831-1899) from Greek diploos "double" (see diplo-) + dokos "a bearing-beam," connected to dekomai "to take, accept, receive," as an agent-noun, so, properly, "which takes on (the load or covering)," from suffixed form of PIE root *dek- "to take, accept." The dinosaur was so called for the peculiar structure of the tail bones.