Monday, March 10, 2014

"Missing Link"?

A few months ago, my dad sent me an article on a new discovery, and I thought it was super cool. A new fish fossil found in China has been attributed to being a possible "missing link" (see picture to the right) between placoderms (an ancient fish group) and modern fish (yes, like Nemo). Apparently, it was a bigger news topic than I had originally thought, as, a few days after I had read it, it was brought up in one of my EEMB classes, Biology of Fishes. The topic of fishes, as suggested in the name, was discussed in depth in the course and opened my eyes to how cool this discovery really was. A little insight into fish evolution: jawless fishes (generally termed "Agnatha"), including the lampreys and hagfish, are thought to have come first. Then, Placoderms, these huge, ancient fishes with bony plates on the outside are thought to have come next. Placoderms had jaws (see left photo), but they were not like hinged jaws today. To open their mouths, Placoderms completely lifted the top part of their head up. Modern bony fish evolved last (like the tuna, in the bottom picture, observe the jaw differences). The jaws of the tuna can open by simply moving their bottom jawbone, without lifting the top of their head. How did we get from this weird, head lifting mechanism thing to having the type of jaws that is generally seen today? Well, this discovery of Entelognathus (try saying that three times fast) provides a possible transition between the bony plated Placoderms and the bony fishes. If this wasn't cool enough, I was again reminded of the news when our class began discussing missing links. Then I realized, a "missing link" had just been found, within the last few months! They called this discovery "one of the most exciting fossil discoveries in the past century..." (see article), and it happened so recently. It was super exciting to see that extremely important scientific discoveries are HAPPENING RIGHT NOW.

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