BROADCASTS.com

b"It's the next in our short series of episodes about mass extinctions! Don't worry, it won't be boring, because we're going to learn about a lot of weird ancient fish too.\\n\\nFurther reading:\\n\\nTitanichthys: Devonian-Period Armored Fish was Suspension Feeder\\n\\nBehind the Scenes: How Fungi Make Nutrients Available to the World\\n\\nDunkleosteus was a beeg feesh with sharp jaw plates that acted as teeth:\\n\\n \\n\\nTitanichthys was also a beeg feesh, but it wouldn't have eaten you (picture from the Sci-News article linked above):\\n\\n\\n\\nPteraspis: NOSE HORN FISH:\\n\\n\\n\\nCephalaspis had no jaws so it couldn't chomp you:\\n\\n \\n\\nBothriolepis kind of looked like a fish in a mech suit:\\n\\n\\n\\nShow transcript:\\n\\nWelcome to Strange Animals Podcast. I\\u2019m your host, Kate Shaw.\\n\\nHere\\u2019s the second in our small series of episodes about extinction events, this one the Late Devonian extinction. We\\u2019ll also learn about some weird and amazing fish that lived during this time, and a surprising fact about ancient trees.\\n\\nThe Devonian period is often called the Age of Fish because of the diversity of fish lineages that arose during that time. It lasted from roughly 420 million years ago to 359 million years ago. During the Devonian, much of the earth\\u2019s landmasses were smushed together into the supercontinent Gondwana, which was mostly in the southern hemisphere, and the smaller continents of Siberia and Laurussia in the northern hemisphere. The world was tropically warm, ocean levels were high, and almost all animal life lived in the oceans. Some animals had adapted to living on land at least part of the time, though, and plants had spread across the continents. The first insects had just evolved too.\\n\\nShallow areas of the ocean were home to animals that had survived the late Ordovician extinctions. There were lots of brachiopods, bivalves, crinoids, trilobites, and corals. Eurypterids were still thriving and ammonites lived in deeper water. But while all these animals are interesting, we\\u2019re mainly here for the fish.\\n\\nThe fish of the Devonian were very different from modern fish. Most had armor. Way back in episode 33 we talked about the enormous and terrifying dunkleosteus, which lived in the late Devonian. It might have grown up to 33 feet long, or 10 meters. Since we still don\\u2019t have any complete specimens, just head plates and jaws, that\\u2019s an estimate of its full size. However long it grew, it was definitely big and could have chomped a human in half without any trouble at all. It\\u2019s probably a good thing mammals hadn\\u2019t evolved yet. Instead of teeth, dunkleosteus had jaw plates with sharp edges and fanglike projections that acted as teeth.\\n\\nAnother huge fish from the Devonian is called titanichthys, which might have grown as long as dunkleosteus or even bigger, but which was probably not an apex predator. Its jaw plates were small and blunt instead of sharp, which suggests it wasn\\u2019t biting big things. It might not have been biting anything. Some researchers think titanichthys might have been the earliest known filter feeder, filtering small animals from the water by some mechanism we don\\u2019t know about yet. Filter feeders use all sorts of adaptations to separate tiny food from water, from gill rakers to baleen plates to teeth that fit together closely, and many others. A study published in 2020 compared the jaw mechanisms of modern giant filter feeders (baleen whales, manta rays, whale sharks, and basking sharks) to the jaw plates of titanichthys, as well as the jaw plates of other placoderms that were probably predators. Titanichthys\\u2019s jaws are much more similar to those of modern filter feeders, which it isn\\u2019t related to at all, than to fish that lived at the same time as it did and which it was related to.\\n\\nTitanichthys and dunkleosteus were both placoderms, a class of armored fish. That wasn\\u2019t unusual, actually. In the Devonian, most fish ended up evolving armored plates or thick scales."