Tuesday, September 15, 2009

Shark Evolution


Since we're studying evolution I thought this was a nice little article about how science works. Let us know your thoughts!
In a Shark's tooth, a new Family Tree

11 comments:

May said...

It's interesting how scientists can tell the lineage of animals by the smallest of details, like the difference in the serrations of great white teeth as opposed to megalodon teeth. It's too bad great white numbers are declining...

AWillingham said...

It's an interesting quirk of evolutionary biology that different scientists can connect the great white to different ancestors; I hadn't realized that it was so subjective. It's also amazing how a tiny detail in tooth structure can completely change theories about shark ancestry. It would be convenient if cartilage could also be preserved in the fossil record!

Tatiana said...

I think it is very interesting that what we think of as such a fierce predator, the great white, actually evolved from a less feared animal. I can see how most people would want to believe that great whites are descendants of the enormous "megashark", and it is very cool that science has come so far as to be able to prove where exactly great whites came from.
-Tatiana

Alice Buckley said...

This article is so interesting because most people aren't even aware that the ancestry and lineage of great white sharks was in debate. It just goes to show that there are still so many things around us in the living world that scientists have yet to completely understand.
The fact that great whites are in danger of extinction demonstrates our need as humans to protect and take care of the world around us, because there are so many things that we still know so little about and if we are not careful they will soon be gone forever along with our chances of studying and learning about them.

Anonymous said...

this is adrienne. this article really shocked me. I would have thought, as the original hypothesis was, that sharks had evolved from the megalodons. It was a suprise that sharks had actually evolved from a smaller ancestor: the mako shark.
This article also shows me how a tooth can lead to a huge controversy and how the laws of natural selection can lead to big discoveries.

Betty Tran said...

I liked the way the picture of the shark made me interested in reading the article. I thought it was interesting how people used to think that the teeth of megalodon were fossilized tongues of dragons. I was fascinated by how significant teeth were to discovering more about how the great white shark came to be.

ΆΛЯΘй said...

How awesome is it that Hubbell found such a complete fossil? It's truly amazing that science has evolved (no pun intended) so much as to be able to see all of these minute details to aid in the determination of a species' lineage. Or the fact that hi-res electron microscopes can see all of the minute differences in the serrations and spacing of the teeth and caused Agassiz's groundbreaking discovery to be reduced to "superficial resemblances." Its truly amazing how such a minute detail can allow for so much change in the debate over the Great White's ancestry. Science is truly remarkable!

~ΆΛЯΘй

Frances Ball said...

Its interesting how most people just assume that if a creature looks like another then it has evolved from it over time. This article shows that if you study these species more closely it is clear that they could have evolved from creatures you would not usually associate them with. I liked the part about the dragon tongues. It was funny that at one point people really thought they were fossilized tongues.

Ben Levy said...

It is always a little bit amazing that by simply examining the teeth of an ancient creature, we can actually find such conclusive evidence about the species' family tree. It seems like you would need many more body parts to come up with a strong conclusion, but the sophistication of the tools scientists are able to use actually make it possible to identify and classify creatures after just examining their teeth. It would be very interesting to understand the story of why the Megalodon shark went out of existence. Perhaps their are similarities to the modern story of the Great White's endangerment.

Lara said...

It seems like the great white shark should be related to and evolved from a megalodon since they are both such ferocious predators. I thought it was very interesting that they are not related and that great whites are actually descendants from mako sharks who have smooth teeth. It surprised me because mako sharks are less vicious than the great white. Its cool that scientists are able to differentiate between two species that are similar and two species that are related. I also thought it was ironic that the man who noticed the similarities between great whites and megalodon, Agassiz, did not believe in Darwinism but Creationism.
-Lollie

Rochelle said...

I think it was interesting how the great white shark actually evolved from a milder, less aggressive shark rather than evolving from the "sea-monster like" megalodons. I also was surprised by the paragraph that talked about trying to find similarities in teeth, and how the measure of similarity depend on the feature and the viewer. It was interesting to see that Agassiz, whose work was related to the idea of common descent, actually did not believe in Darwin's theory.