The Evolution of Ichthyosaurs- Large Aquatic Reptiles
explanatory Essay
1068 words
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 foun...
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...tyles in Jurassic ichthyosaurs”. Journal of Vertebrae Paleontology 21 (No. 1): 61-73.
Mason, Betsy. “Ichthyosaur find may challenge notions about prehistoric migrations”. Stanford Report.com 7 February 2003. 20 March 2004.
< http://news
service.stanford.edu/news/2003/february12/ichthyosaur-25.html>
Motani, Ryosuke. “Rulers of the Jurassic Seas”.
ScientificAmerican.com 19 December 2000. 22 March 2004.
<http://www.sciam.com/article.cfm?articleID=00092A8F-A178-1C72-9EB7809EC588F2D7&sc=I100322>
Perkins, Sid. “Sea Dragons”. Science News Online 162 (No. 8): 1-11. 24 Aug. 2002.
<http://www.sciencenews.org/articles/20020824/bob10.asp>
Pickrell, John. “Ichthyosaur’s Turtle Supper Causes Extinction Debate”. National Geographic News.com 5 August 2003. 22 March 2004.
<http://news.nationalgeographic.com/news/2003/08/0805_030805_ichthyosaur.html>
In this essay, the author
- Explains the evolution of ichthyosaurs, a large aquatic reptile that migrated just like whales do today.
- Explains that andrea fildani and michael shultz discovered the bones of an ichthyosaur near the southernmost tip of chilean patagonia.
- Explains that ichthyosaurs transitioned their body from a lizard-shaped body plan to fish-like one through the early and middle triassic periods. in 1927, the first bone fragments were found.
- Explains that ichthyosaurs developed the most superbly adapted body form for life in water from obscure origins.
- Explains that ichthyosaurs swam like eels, rolling their entire body, and the shape of their vertebrae was similar to a shark.
- Explains that ichthyosaurs were fast and strong swimmers with four, physically powerful, crescent-shaped fins. they swam in a fish-like fashion, propelling themselves through the water.
- Explains that ichthyosaurs are known for their gigantic eyes, measuring in length of 264 mm across. their calculations of the eye’s f-number determined the relative brightness of an optical system.
- Explains that ichthyosaurs had exceptionally well-developed sclerotic rings, a doughnut-shaped bone embedded within the eyeball. the rings were believed to help keep the eyes in shape.
- Explains that the fine-grained remains that were encased in the prehistoric reptiles' stomach also preserved verification of the creatures' abdomen diet.
- Explains that ichthyosaurs have fascinated the interests of palaeontologists because they evolved from land-dwelling animals, which themselves had descended from an ancient fish.
- Explains that ichthyosaur find may challenge notions about prehistoric migrations.
- Cites perkins, sid, and pickrell, john. "ichthyosaur's turtle supper causes extinction debate".
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