The gang discusses two papers about things with legs…. and the word snake is their name. Honestly, we’ve had flimsier excuses for a podcast, just go with it. The first paper looks at a specimen of a legged snake, and the second paper discusses potential evolutionary pathways for convergent evolution in a group of penguin like animals closely related to snake birds (Plotopterids). Meanwhile, Amanda’s computer is doing just fine, James is otter-ly amazing, and Curt knows when to end on top.

Up-Goer Five (Curt Edition):

Our friends talk about two papers which look at animals with legs. The first is an animal that today doesn't have legs but a long time ago animals like it did have legs, very tiny and weird legs. This first paper talks about a dead body of one of these animals with tiny weird legs from a long time ago which has more parts than most. Most other dead bodies we find do not have much of a head, which is really important for deciding how much these old things from a long time ago are the same as the animals that don't have legs today. This dead body has a head, which is cool. It seems that animals without legs first had heads that look like they are today and then lost their legs.

The second paper looks at animals that usually fly but these animals move through water. Some animals move through the water with their arms, but others use their legs to push them through the water. The ones that use their legs seem to drop into the water from above, while others of these animal that can not fly use their arms to move in the water. However, some older animals use their legs to move in the water and did not fly, so this is hard to say for sure. There are also animals in the past who looked like the animals that do not fly, but they seem to move in the water with their legs, not their arms.

References:

Garberoglio, Fernando F., et al. "New  skulls and skeletons of the Cretaceous legged snake Najash, and the  evolution of the modern snake body plan." Science advances 5.11 (2019): eaax5833.

Mayr, Gerald, et al. "Comparative  osteology of the penguin‐like mid‐Cenozoic Plotopteridae and the  earliest true fossil penguins, with comments on the origins of  wing‐propelled diving." Journal of Zoological Systematics and Evolutionary Research (2020).

The gang celebrates hitting the milestone of 200 podcast episodes by returning to a topic related to their first episode, sharks. The first paper looks at how shark size has changed through time, and the second paper looks at the different ways whirl-toothed sharks were able to eat their food. Meanwhile, James has ideas about the success of Disney movies, Amanda comes back at the wrong time, Curt quotes the good batman movies, and everyone has real troubles just starting the damn podcast (Podcast officially starts getting on topic at 18:15).

Up-Goer Five (James Edition):

This week the group recognize their two hundred shout sound by looking at some papers that cover an idea that is close to an idea they talked about when they did their first real shout sound (which is not the first actual shout sound). The first paper is looking at how big animals that live in the water and have big teeth get large. It gets lots of teeth and looks at animals that live in the water and have big teeth today as well as some animals that live in the water and have big teeth that lived in the past and are known from their whole bodies in order to work out how big they got from just their teeth. It then asks why they got big, and suggests a number of reasons such as that maybe the need to have big babies made them get big, which made them have bigger babies and made them get bigger still. The other paper looks at some weird animals that live in the water with big teeth that have teeth running down the middle of the mouth rather than around it. It looks at both the teeth and also the rest of the head in a couple of animals and shows that they eaten in different ways, and that some would have used their strange teeth to pull animals with many arms from their hard homes, while others would break the homes of the animals with many arms to eat them.

References:

Tapanila, Leif, et al. "Saws, scissors, and sharks: Late Paleozoic experimentation with symphyseal dentition." The Anatomical Record 303.2 (2020): 363-376.

Shimada, Kenshu, Martin A. Becker, and  Michael L. Griffiths. "Body, jaw, and dentition lengths of macrophagous  lamniform sharks, and body size evolution in Lamniformes with special  reference to ‘off-the-scale’gigantism of the megatooth shark, Otodus  megalodon." Historical Biology (2020): 1-17.