What about the Ichthyosaur? Could you imagine what life on earth would be like if the prehistoric reptiles had still existed? Or would we even be in the picture? There are many questions one could come 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: the Ichthyosaur, half reptile-half fish, or so paleontologists have said. It would be rather difficult to think of such a living creature, since sea turtles are the closest thing one could imagine to be half fish- half reptile. But the sea turtle is only a small fraction in body size compared to this enormous creature! So, what about the Ichthyosaur? For one thing, the ichthyosaur is one of the most ancient creature we know about. It first appeared approximately fifteen to twenty million years before the first dinosaur.
This is a fact that a lot of people still do not know. The ichthyosaur was one of the most predominant marine 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 dinosaur disappeared. 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 the ichthyosaur that caused it to become extinct before the last dinosaur disappeared? This is the question still floating in the minds of many paleontologists.
What one can make do with is the evidence of their existence, the fossils. With the recent and continued findings of ichthyosaur fossils, the pieces of the puzzle are slowly put together. In this paper, we will discuss how these findings had led paleontologists to believe that the ichthyosaur had evolved from reptilian to marine life. More importantly, the key processes in biology and other 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 it branched off was a very complicated task for many.
This problem of course stemmed from the fact that the fossils had characteristics that hinted it was reptilian and characteristics that hinted it might also be a fish. In early book publications, there was some debate about what exactly this ichthyosaur should be categorized as. One book author had stated that ichthyosaurs had bodies that were highly modified for swimming that they must have been virtually helpless on land.(87)1 Another book author had similar views. Ichthyosaurs were thought to come out on land from time to time, like seals and crocodiles…It turned out that the animal had been entirely a creature of the sea(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 fossil called Utatsusaurus hataii in Japan. His findings were reported by a fellow student at the University of California, Berkeley. In the article Motani had stated that ichthyosaurs are diapsids..nevertheless[he said] they are closer to living reptiles than are turtles.3 In that same article, Sanders stresses that this find makes categorizing the ichthyosaur difficult because they became so well adapted to their marine environment that they developed many features similar to marine organisms such as fish and dolphins.
This obscured their real origin.3 Last month, through further analysis, Motani had reported his examinations of this half-reptilian half-fishlike creature led him to believe it evolved not from fish but from land dwelling animals, which themselves had descended from an ancient fish.4 This find is controversial. Does this mean they once lived on land? As an 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 change the whole perspective of how one animal or plant lived its life. If the ichthyosaur was never found in its more reptilian-formed fossil, scientists would probably conclude that it was just some big funny looking fish that came before the dinosaurs. This shows how important phylogeny trees are in tracing evolution. Most importantly, these fossils become 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 their extinction. The fact that this prehistoric marine reptile is extinct is enough to stir the minds of scientists, but what we all want to know is why they became extinct before the dinosaurs. These fish lizards were the cheetahs and the tigers of their time . They predominated the Mesozoic sea, like the dinosaurs did the land. So what on earth would cause them to go extinct? There are so many theories that have been proposed concerning the mass extinction of these prehistoric reptiles.
As Colbert and Morales would put it: the conditions changed, and for some reason, the ruling reptiles were unable to adapt themselves to the changing world (214).5 This is one of the most common theories of the extinction of not only ichthyosaurs but also other animals. Darwin himself would say he said so. The findings of these particular fossils only strengthens his ideal of evolution and natural selection. These include the change in the lower arm bone, the finger bones ( length and addition, subtraction and division of digits), and the shape of the trunk vertebrae6. But even with these changes to adapt to the changes in environment, it is still not clear why this mysterious creature disappeared from the face of the earth. Because of science and technology, we have succeeded in mapping our place on the timeline, and discovering the creatures before us.
With the discovery of fossils, we are able to study the anatomy of so many organisms, and to draw conclusions. Through building phylogeny trees, we are able to trace their origins and hypothesize their evolution and extinction. The ichthyosaur fossil is only one of so many fossils that have helped trace our way back to prehistoric times. Now the challenge is placing that last piece of the puzzle. A question that has been asked for so many years: What caused the extinction? This is not only the question for the ichthyosaur, but other animals, and what this means.
How long will it be before this phenomenon catches on to the human race? Thanks to this fish lizard, we are one step closer to knowing.