The Dinosaurs of Wyoming - Wyoming State Geological Survey ...

68 THE DINOSAuRS OF WYOMIITG
of the sand-grains themselves show them to be angular with
slightly abraded corners, sand of aqueous deposit; but apparently
laid down in a lake or bayou. rather than in a normal
river as indicated by the absence of clay and the presence of a
lime cement. The cross-bedding which the rock exhibits could
readily have been made by wave action along the shores of a
comparatively shallow delta-lake or bay, and the track, which
FIGURE 17A
Fossil footprints of three·toed Dinosaurs from the Newark series, Triassic, of the
Connecticut Valley. These are preserved in Yale University Museum. Note the small
tracks in larger slab.-Courtesy of Professor R. S. Lull.
is that of a very young animal, was evidently made under water.
The character of the sediment does not give evidence of much
vegetable matter at the particular point where the track was
made. The footprint is that which one would expect from the
known character of the sauropod foot, and is evenly impressed
throughout as though the animal's weight were borne equally
over the entire sole, evidence in favor of a true walk rather than
a sprawling crawl, at any rate when the body was partly waterborne.
"I believe these animals to have been truly aquatic though
capable of coming ashore where the substratum was sufficiently
firm to support the immense weight, and, while they show no
trace of swimming appendages, they doubtless could swim as a
hippopotamus does."