What About The Ichthyosaur Essay, Research Paper

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.