Scientists have determined that with the jaws in fish appeared real teeth


18/10/2012

Paleontologists from the European X-rayed by microtomograph fossilized remains the most primitive jawed fish and found that these creatures have full teeth and bony outgrowths not, as previously thought.

Martin Ryuklin director team of scientists at Bristol University, said - "We were lucky to get a picture of all the lines of growth, the cells and tissues inside the bones of the jaw. This has helped us to learn how to develop this part of the skeleton of the ancient fish. Comparing these data with the way the current vertebrate embryos are formed, we found out that the first vertebrate fish with jaws (armored) possessed teeth. "

Ryuklin colleagues tried to find a solution to one of the most controversial issues of paleontology - the cause and time of occurrence of vertebrate teeth. The majority of scholars believe that the sharp points of the mouth of primitive fish were not real teeth, but were bony outgrowths on the jaws, which are on the mechanical properties and the structure of the bone did not differ. Other paleontologists in doubt, because the structure of these regions has not been investigated because of the lack of the necessary procedures.

The studies filled the gap prorentgeniv jaw of one of the most primitive crustacean species - Compagopiscis croucheri - a new technique to microtomography, which has been developed by Swiss physicists Paul Scherrer Institute and Technical High School in Villigen and Zurich.

High resolution tomography has allowed researchers to examine the internal structure of the jaw, and determine the types of tissues that make up parts of it. The lower jaw of the fish was part of the cartilage tissue, suggesting that it is closely related to non-pedestal, more primitive vertebrates.

However, the upper area of the lower jaw and zuboobraznye projections were composed of two types of bone matter with radically different properties and structure.

Researchers have considered the structure of the jaw protruding from Compagopiscis croucheri and isolated layers of pulp, dentin, and other dental tissues. Their arrangement and shape, according to scientists, is very similar to other ancient teeth of vertebrates, as well as with preparations of teeth in the embryos of some of today’s fish, including sharks kolyuchkozubyh extinct and living "resources" in the form of Dipnoi (lungfish) and Holocephali (fish- chimeras).

Paleontologists believe that the opening in Compagopiscis croucheri teeth, suggests that even the jaw, the most primitive fish had full teeth. It is likely that the first teeth of fish with jaws appeared or were "created" by nature after the jaw fish.

Philip Donohue, another author of the paper from Bristol University, concludes - "This" iron "in the direction of the evidence that the first vertebrate jaw had teeth that finally allows us to complete the debate on the formation of teeth."


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