• Webster's Revised Unabridged Dictionary
    • n Brontozoum (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.
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Century Dictionary and Cyclopedia
    • n brontozoum A genus of gigantic animals, formerly supposed to be birds, now believed to be dinosaurian reptiles, known only by their tracks in the Triassic formation of the Connecticut valley. The stride was about 8 feet, and the length of the footprint about 17 inches.
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Webster's Revised Unabridged Dictionary
NL., fr. Gr. thunder + animal


In literature:

The second species of the same genus is the BRONTOZOUM SILLIMANIUM.
"Remarks on some fossil impressions in the sandstone rocks of Connecticut River" by John Collins Warren