The Evolution of Ichthyosaurs- Large Aquatic Reptiles
In the early 1800’s, a new discovery that left paleontologists in awe was the fossil finding of the immeasurable amount of species of reptiles, Ichthyosaurs. Greek for “fish lizards”, these fossils were found all over the world. Because these large aquatic reptiles migrated just as whales do today, paleontologists have had the amazing advantage of collecting fascinating bone fragments throughout the past 177 years. Ichthyosaurs swam the ocean life from about 245 million until about 90 million years ago- approximately the same time dinosaurs ruled the land. The earliest Ichthyosaur fossil findings were in parts of Canada, China, Japan, and possibly Thailand. Countless fossils came from coatings of limestone produced out of the ocean-floor ooze that was predominantly superior at preserving very well facts of the creatures it digested (Perkins 2).
Andrea Fildani and Michael Shultz, graduate students in the Department of Geological and Environmental Sciences, uncovered the bones of an Ichthyosaur near the southernmost tip of Chilean Patagonia. These rock layers were initially deposited at the floor of an ocean more than 100 million years ago. In their findings of the Chilean boulder, they were fortunate enough to find 17 vertebrae along with neural arches that encircle the spinal cord as well as some ribs. Paleontologists firmly agreed with Fildani’s notion that the bones had been 8 to 9 feet long and had existed around 140 million years ago (Mason 1).
As time progressed, Ichthyosaurs transitioned their body like features from a lizard-shaped body plan to a fish-shaped one through the early and middle Triassic periods. In 1927, the first bone fragments were found and they illustrated the Ichthyosaurs image of having a boneless tail, dorsal fins, and thickset legs that transformed into flippers. Even though they appeared as fish-shaped animals, they were really air-breathing reptiles. They did not have gills, and the configurations of their skull and jawbones were indisputably reptilian. They were better adapted than any other reptiles; nevertheless, they still needed to go to the surface sporadically to breathe air (Motani 1).
Benjamin Kear, paleontologist at the South Australia Museum in Adelaide cited, “From obscure origins, Ichthyosaurs developed the most superbly adapted body form for life in water” (Pickrell 1). Ichthyosaurs had many distinct and unique features such as limb skeletons that looked like corncobs, gigantic eye bones, and a vertebra that resembled hockey pucks or ashtrays.
When Ichthyosaurs first appeared in lizard shape, the quantity of trunk vertebrae significantly increased. These Ichthyosaurs probably swam like eels, by rolling their entire body. Then, as fish-shaped Ichthyosaurs developed from among the lizard-shaped ones, the body solidified together with the vertebral column. Coming in various shapes and sizes, the interesting shape of...