diplodocus (n.) Look up diplodocus at Dictionary.com
1884, coined in Modern Latin in 1878 by U.S. paleontologist Othniel Charles Marsh (1831-1899) from Greek diploos "double" (see diploid) + dokos "a beam," from suffixed form of PIE root *dek- "to take, accept." So called for the peculiar structure of the tail bones.