The mosasaurs of the late Mesozoic were the only real sea serpents of the geologic ages. They were something like the ichthyosaurs, but with smaller heads and much longer, more slender, serpentlike bodies. Some grew to be thirty or forty feet long.
Plesiosaurs were perhaps the strangest of all the Mesozoic marine reptiles. They grew to be forty to fifty feet long, with stout body, very long, slender neck, small head, short tail, and four long, powerful swimming paddles which were distinctly leglike. These and the mosasaurs were both flesh eaters, as shown by the sharp teeth.
Plate 15.—(a) Restoration of a Late Paleozoic (Coal Age) Landscape. Showing the main kinds of plants which have entered into the making of most of our coal. Giant “club mosses” both with and without branches, in the left background; giant “horsetail” (or “scouring rush”) plants on the right; and seed ferns in the left foreground. A primitive reptile in the water; two large amphibians or giant salamanders, called “stegocephalians,” on the land; and a great “dragon fly,” two feet wide, in the air. (From a drawing by Prof. Williston. Courtesy of D. Van Nostrand Co.)
Plate 15.—(b) Photograph of a Fossil Fern or Seed Fern Frond on a Piece of Shale Millions of Years Old. The specimen is of the Pennsylvanian Age and was taken from the coal fields of Pennsylvania. (After White, U. S. Geological Survey.)
