What’s it about?
Using tomographic data, the authors tease the different growth stages of the lower jaws of placoderms apart and show that the development of teeth are separate from the development of the jaw bone itself.
Why does it matter?
Paleontologists argue about whether placoderms are an offshoot of the animals that lead to modern fishes (and ultimately to us) or if they are directly along this lineage. Primary evidence for either argument comes from the pattern of growth of teeth in placoderms (or discussions of whether they really are teeth).
Why did I read this?
This paper was potential assigned reading for my EES 270 class. I ultimately didn’t use it, though it is super interesting
What did I learn?
Placoderm teeth are, in fact, teeth and share the same developmental origin of modern jawed vertebrates. This means that teeth evolved before placoderms became distinct from other jawed vertebrates.