The gang discusses two papers that look at changes in teeth through time. The first paper looks at the earliest example of heterodont teeth in tetrapods, and the second paper looks at how different mammal groups build sabre tooth morphologies. Meanwhile, James has unique ideas for building worker morale, Amanda accidentally makes a pie faux pas, and Curt is friend to gelfling.

 

Up-Goer Five (Amanda Edition):

Today our friends talk about teeth. Wow, teeth is one of the ten hundred most used words. Cool. So some things have teeth that are all the same kind. Most of the very early things with four feet that go on long have teeth of all the same kind. But there is an early thing with four feet that goes on land that we have known about for a long time that was never really looked at too close and now we see that it has teeth that are big and round and teeth that are small and pointed. It was probably eating things that were very hard and needed to be broken up before it could eat them. What is cool is that there are lots of animals from the same place at the same time that also show this kind of eating thing, where they must have been eating things that were very hard like rock and had to be broken up before they could be eaten. Our friends also talk about animals with hair that had very very long pointed teeth in the front of the mouth. It turns out that these teeth grow in a very different way. Animals with hair only grow teeth two times, and the back teeth only grow in one time. Usually the back teeth grow in last. But these animals had their very very long pointed front teeth grow in last. And they grow in funny. They grow in along the inside of the old teeth, until they are as much as the old teeth, then the old teeth fall out. This might mean that these teeth show up in different animals with hair totally on their own over and over and over again many times, which is cool.

References:

Clack, Jennifer A., et al. "Acherontiscus caledoniae: the earliest heterodont and durophagous tetrapod." Royal Society open science 6.5 (2019): 182087. 

 Wysocki, Matthew Aleksander. "Fossil evidence of evolutionary convergence in juvenile dental morphology and upper canine replacement in sabertooth carnivores." Ecology and Evolution (2019).