Sawfish ‘Teeth’ Didn’t Pave The Way For Modern Chompers
(Click to enlarge) Similar to the skin denticles from which they are derived, saw teeth develop by filling in open spaces created as the snout grows. (Credit: Norbert Wu/Minden Pictures,Newscom)
Sawfish and sawsharks are aptly named for their long, serrated snouts. These jags may look like teeth, but they’re actually modified versions of denticles—the hardened scales that cover the skin of sharks and rays.
(From Science / by Jennifer Balmer) — Recently, scientists have wondered whether the structures could provide clues to the origin of true teeth, which also may have evolved from skin denticles. In a new study, researchers used x-ray computed tomography (CT) imaging to produce 3D depictions of real and saw teeth belonging to embryos and adults of prehistoric and present-day saw-bearing fishes (such as the one pictured). They found clear differences in how saw teeth and oral teeth grow. Similar to the skin denticles from which they are derived, saw teeth develop by filling in open spaces created as the snout grows.
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