Saturday, July 20, 2019

The Evolution of Ichthyosaurs- Large Aquatic Reptiles Essay -- Anthrop

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 â€Å"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 foun... ...tyles in Jurassic ichthyosaurs†. Journal of Vertebrae Paleontology 21 (No. 1): 61-73. Mason, Betsy. â€Å"Ichthyosaur find may challenge notions about prehistoric migrations†. Stanford 7 February 2003. 20 March 2004. < http://news> Motani, Ryosuke. â€Å"Rulers of the Jurassic Seas†. 19 December 2000. 22 March 2004. Perkins, Sid. â€Å"Sea Dragons†. Science News Online 162 (No. 8): 1-11. 24 Aug. 2002. Pickrell, John. â€Å"Ichthyosaur’s Turtle Supper Causes Extinction Debate†. National Geographic 5 August 2003. 22 March 2004.

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