Podcast 241 - The Shark and the Whale

The gang discusses two papers that look at what past sharks might have eaten. The first paper uses nitrogen isotopes to determine the trophic level of species belonging to the extinct shark genus Otodus, and the second paper shows evidence of predation/scavenging of sperm whales by sharks in the late Miocene. Meanwhile, James has a couch to burn, Curt proposes an experiment to find the best animal, Amanda becomes shark Nietzsche.   Up-Goer Five (Curt Edition): Our friends look at two papers that look at what big angry animals with big teeth who breathe water and lived in the past could have eaten. The first paper looks at the parts of these animals from the past and uses what those parts of made of to try and see what kind of things they might have eaten. This is the first time that this has been done using these parts of the animal, since most of these kinds of papers look at living animals and so they can get parts that do not last when the animals die. It had been said that these big angry animals in the past may have eaten big animals that eat small things, and that they might have died out when there was less big animals that eat small things. This paper finds that the parts that make up these animals show that maybe these animals were eating things that ate other bigger things, that these big animals were probably not just eating this one type of animal but may have gone for anything, as well as other animals that also eat pretty much everything. One animal that they mention these big angry animals that breathe water could have eaten is a big animal with warm blood and big teeth that lives in water. The second paper looks at how the hard parts of big animals with warm blood and big teeth that live in water at this time have hurt marks on their hard parts that look like they were from the teeth of big angry animals that breathe water. These hurt marks are along a part of the head that has a lot of stuff in it which animals would like to eat. The hurt marks are all different, with some that look like the animal bit them right on the head, and others look like marks from teeth that were biting at the body when it was already dead. It seems like many different types of angry animals with big teeth who breathe water may have been eating these animals with warm blood and big teeth.   References: Kast, Emma R., et al. "Cenozoic megatooth sharks occupied extremely high trophic positions." Science Advances 8.25 (2022): eabl6529. Benites-Palomino, Aldo, et al. "Sperm  whales (Physeteroidea) from the Pisco Formation, Peru, and their trophic  role as fat sources for late Miocene sharks." Proceedings of the Royal Society B 289.1977 (2022): 20220774