The Collaborative International Dictionary of English v.0.48:

Otozoum \O`to*zo"um\, prop. n. [NL., fr. Gr. ?, a fabled giant +
   zo^,on an animal.] (Paleon.)
   An extinct genus of huge vertebrates, probably dinosaurs,
   known only from four-toed tracks in Triassic sandstones.
   [1913 Webster]