Could you imagine what life on earth would be like if the prehistoric reptiles hadstill existed? Or would we even be in the picture? There are many questions one couldcome up with when coming across the fossilized remains of an extinct species.
Dinosaurs have always been the reptile of interest among many, but check this out: theIchthyosaur, half reptile-half fish, or so paleontologists have said. It would be ratherdifficult to think of such a living creature, since sea turtles are the closest thing one couldimagine to be half fish- half reptile. But the sea turtle is only a small fraction in body sizecompared to this enormous creature! So, what about the Ichthyosaur? For one thing, theichthyosaur is one of the most ancient creature we know about. It first appearedapproximately fifteen to twenty million years before the first dinosaur. This is a fact thata lot of people still do not know.
The ichthyosaur was one of the most predominantmarine reptiles of its time, and became extinct about 110 million years ago. Furthermore,this fish lizard became extinct approximately 45 million years before the last dinosaurdisappeared. There are many theories on the mass extinction of the prehistoric reptiles,most of which is centered upon the disappearance of the dinosaur. What happened to theichthyosaur that caused it to become extinct before the last dinosaur disappeared? Thisis the question still floating in the minds of many paleontologists.
What one can make dowith is the evidence of their existence, the fossils. With the recent and continued findingsof ichthyosaur fossils, the pieces of the puzzle are slowly put together. In this paper, wewill discuss how these findings had led paleontologists to believe that the ichthyosaur hadevolved from reptilian to marine life. More importantly, the key processes in biology andother fields of science are used in making, researching, and interpreting these finds. As with any new find, a scientist would initially try to classify the organism.
Placing the ichthyosaur in the right spot on a family tree and determining when itbranched off was a very complicated task for many. This problem of course stemmedfrom the fact that the fossils had characteristics that hinted it was reptilian andcharacteristics that hinted it might also be a fish. In early book publications, there wassome debate about what exactly this ichthyosaur should be categorized as. One bookauthor had stated that ichthyosaurs had bodies that were highly modified for swimmingthat they must have been virtually helpless on land.
(87)1 Another book author hadsimilar views. Ichthyosaurs were thought to come out on land from time to time, likeseals and crocodiles. . .
. It turned out that the animal had been entirely a creature of thesea(214). 2 In 1982, Ryosuki Motani, a student from the University of California,Berkeley , and his colleagues had excavated a 240 million-year-old ichthyosaur fossilcalled Utatsusaurus hataii in Japan. His findings were reported by a fellow student at theUniversity of California, Berkeley. In the article Motani had stated that ichthyosaurs arediapsids.
. . neverthelesshe said they are closer to living reptiles than are turtles. 3 Inthat same article, Sanders stresses that this find makes categorizing the ichthyosaurdifficult because they became so well adapted to their marine environment that theydeveloped many features similar to marine organisms such as fish and dolphins. Thisobscured their real origin. 3 Last month, through further analysis, Motani had reportedhis examinations of this half-reptilian half-fishlike creature led him to believe it evolvednot from fish but from land dwelling animals, which themselves had descended from anancient fish.
4 This find is controversial. Does this mean they once lived on land? Asan amateur scientist, one can’t even comprehend if this creature evolved once, or twice!It is absolutely shocking how a simple classification, from worms to whales , can changethe whole perspective of how one animal or plant lived its life. If the ichthyosaur wasnever found in its more reptilian-formed fossil, scientists would probably conclude that itwas just some big funny looking fish that came before the dinosaurs. This shows howimportant phylogeny trees are in tracing evolution.
Most importantly, these fossilsbecome a key to learning the past before us. Classifying the ichthyosaur was only one piece added to the large puzzle. Another issue that arises from the discovery of ichthyosaur fossils is the time of theirextinction. The fact that this prehistoric marine reptile is extinct is
