Bron`to*zo"um (?), n. [NL., fr. Gr. thunder + animal.] Paleon.
An extinct animal of large size, known from its three-toed footprints in Mesozoic sandstone.
⇒ The tracks made by these reptiles are found eighteen inches in length, and were formerly referred to gigantic birds; but the discovery of large bipedal three-toed dinosaurs has suggested that they were made by those reptiles.
© Webster 1913.