Picks from the Past: February 1941

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How big is a big sauropod track? The young man examining this one, even to the point of taking a bath in the crazy thing, is young Tommy Pendley, who just wanted to find out. The footprint held eighteen gallons of water. Hailing from Cleburne, Texas, Tommy was the three-year-old son of one of the men engaged on the project. Beside it is shown the footprint of a large modern elephant reproduced in the same scale for comparison with the dinosaur footprint.

Roland T. Bird

Scientific detective work sheds new light on the habits and appearance of the most gigantic animals that ever roamed the earth, when the biggest footprints ever found are placed on display.

Piecing together the story of prehistoric animal life is, in its entirety, a gigantic scientific detective problem. Rarely, however, does the process suggest so closely the classic methods of Sherlock Holmes as in the case of the footprints of the "Thunder Lizard," for important new information on the appearance and mode of life of this titanic dinosaur has been deduced from the trail which he left in mud some 120 million years ago.

The general appearance of the “Thunder Lizard” has been known from abundant skeletal remains, fossilized in the rock pages of the earth’s history. But whether he walked on his four feet and trod the dry earth or lumbered about in shallow water, remained unknown, along with other important facts, until the eye of science fell upon these tracks.

Of all creatures that ever walked on earth, the “Thunder Lizard,” Brontosaurus, and other dinosaurs of his group, the sauropods, hold the world’s record for size. Indeed, they seem to have reached the possible limit that an animal with feet could attain. A few other sauropods were larger, but Brontosaurus is typical of the group.

One day late in November, 1938, while prospecting 80 miles southwest of Ft. Worth, Texas, I noted three or four huge depressions in the bed of the Paluxy River, —footprints of these gigantic monsters. On a rock ledge leading underwater was undoubtedly a trail left by a 60- or 70-foot sauropod weighing 20 or 30 tons, probably the “Thunder Lizard” himself. Specimens of this sort were hitherto unrecorded, and I faced the problem of removing a suitable selection for the American Museum.

The task promised to be in keeping with the magnitude of the tracks involved. How would one cope with the whims of a temperamental river while tracing 38-inch footprints underwater? By what method could a suitable section be removed from the solid rock? At each stride the animal moved ten or twelve feet. Where, indeed, could such a large exhibit find room in the Museum’s halls?

Almost two years later to a day, after five months of intensive work, the largest single display of dinosaur tracks ever uncovered was boxed up. With so great a wealth of material available, two other institutions shared in the collection. In all, 40 tons of track-bearing rock were removed from the river bed.

Visitors to the new Jurassic Hall in the American Museum will in time see the original footprints mounted in the base of the gigantic skeleton of the “Thunder Lizard.” As if this 120-million-year-old monster had just strolled into his present position in the hall, you will see the tracks as he would have left them, six front and six hind footprints, under glass resembling the water in which he waded. This solution of the exhibition problem had already occurred to curator-chief Barnum Brown’s fertile imagination before the venture was assured.

What the tracks revealed and how they were removed with the aid of the Texas State-Wide Paleontological Survey, a Works Progress Administration Project, is told in these pages, To Dr. E. H. Sellards of the Bureau of Economic Geology of Texas goes credit for having made possible this valued assistance. To all my other Texas friends, far too numerous to mention singly, who helped in this quest, both at Glen Rose and Bandera, where one other known locality for this type of track was found by us, I extend my heartfelt thanks.