The Mosasaurs

Mosasaurs retain many of the attributes of their terrestrial ancestors. Unlike ichthyosaurs and plesiosaurs, which are presumed to have had smooth skin, mosasaurs still had reptilian scales. Their ancestry can be traced to ancient snakes, although for many years some paleontologists have thought that mosasaurs were more closely related to extinct monitor lizards. Mosasaur species ranged in size from the length of a minibus to that of the longest tractor-trailer, from about 10 to 57 feet (3 to 17.5 m).

Mosasaurs were the latecomers of the Mesozoic marine reptiles. They first appeared about 90 million years ago, during the Late Cretaceous. By that time, the ichthyosaurs were nearly extinct and the last act of the non-avian dinosaurs was being played out. One reason the mosasaurs were successful was that they probably helped fill the ecological niche left open by the demise of the fish- and squid-eating ichthyosaurs. Mosasaurs competed with many other formidable creatures in the ocean, particularly the remaining giants of the marine reptiles—the plesiosaurs and pliosaurs.

Mosasaurs radiated rapidly and spread across much of the globe. A few million years after they originated, they were already the most dominant type of marine reptile. During their Late Cretaceous reign, they spread to all the major oceans of the world, nearly from pole to pole. Their remains have been found in such widespread locations as the United States, Canada, Europe, South America, North Africa, the Middle East, New Zealand, and even Antarctica.

0 0

Post a comment