Palaeo After Dark

The gang discusses two papers that look at how the morphology of tetrapods (animals with four limbs and a backbone) has changed over time. One paper looks at how dinosaur jaws are related to diet preferences, and the other paper looks at how spines have changed as tetrapods diversified through time. Meanwhile, James talks Star Trek, Curt gives some consumer advice, and Amanda would rather not talk about cowboys.

Up-Goer Five (James Edition):

This week the group look at two papers that are looking at different ways that animals get more different. The first paper is looking at the mouths of big angry animals with no hair. The big angry animals with no hair that eat other animals and get big have the least different mouths from each other, but those that are small and eat other animals have very different mouths from one another, and those that eat living things that make their own food or both other animals and living things that make their own food have the most different mouths from one another. We see the same thing no matter how we decide how different mouths are.

The other paper is looking at the line of hard bits in the back of animals that do have hair to see if they get more different over time and do different things along the same line of hard bits. We find out that the line of hard bits do get more different over time, and that the reason they get more different may be because the animals with hair start to breathe more air.

References:

 Jones, Katrina E., Kenneth D. Angielczyk, and Stephanie E. Pierce. "Stepwise shifts underlie evolutionary trends in morphological complexity of the mammalian vertebral column." Nature communications 10 (2019). 

 Schaeffer, Joep, et al. "Morphological disparity in theropod jaws: comparing discrete characters and geometric morphometrics." Palaeontology (2019).