Nautiloids Thrived For 500 Million Years Until These Guys Showed Up

Earth oceans have changed a lot in the last half billion years or so diverse animal groups emerged thrived and vanished entire ecosystems and seascapes have come and gone and nearly everything was killed off a couple of times at least but through all that change one thing has remained the same almost as long as there has been complex animal life in the oceans there have been nautiloids this group of ancient cephalopods squid and octopus relatives have been a constant presence for around 500 million years and we even still have species around today in the form of nautiluses but around 30 million years ago they suffered a mysterious catastrophe something gradually began to push them from their former Global range into a single remaining Refuge the Deep tropical waters of the indo-west Pacific but a refuge from what these hearty survivors had made it through everything the planet had thrown at them across deep time from a devastating asteroid impact to massive volcanic eruptions but this was a very different kind of threat the evolution of a new group of predators that would nearly finish them off seals nautiloids probably emerged in the early Cambrian Period but the oldest Undisputed fossils only date back around 490 million years and this was just 30 or 40 million years after the Cambrian explosion when complex recognizably animal fossils started becoming common in the fossil record and since then not always have endured and survived quite a lot including all five mass extinction events in this planet's history not to mention the emergence of pretty much every major group of marine Predators from sharks to mosasaurs and ichthyosaurs to whales so it's fair to say this isn't their first rodeo and some of their most iconic traits are thought to be ancient adaptations for dealing with these threats like their famous coiled shells for example these started out straighter and almost horn-shaped in the late Cambrian the more predator-resistant coiled forms only evolved later around the time that early jawed fishes and predatory cephalopods arrived on the scene the Heyday of nautiloids seems to have been the ordovician period from around 485 to 444 million years ago when they were at their most diverse though they remained pretty widespread for a long time after that and while their diversity has slowly declined since then around 30 million years ago Nautilus fossils began to vanish from the fossil record of marine environments across the world this contraction of their range eventually left them confined to one small corner of the oceans the only place that they're found today the Deep Waters of the tropical indo-west Pacific and the exact reason for this Sudden Change of Fortunes has been tricky for scientists to explain whatever pushed the nautiluses into their last Refuge also still seems to be preventing them from expanding out of it today but what could be keeping down a group with such a strong record of coping with all kinds of environmental and ecological challenges since at least 1979 the leading assumption has been that it was probably some complex interplay of changing ocean circulation and temperature shifts over time but in 2019 a group of researchers began to wonder if it could be something much simpler maybe even as simple as a new group of predators that the nautiluses just couldn't deal with their approach to investigating this was pretty simple too over the next few years they gathered as much data as they could on the global distribution of nautiluses as well as their possible predators and other threats throughout the last 66 million years and when they publish their analysis in 2022 they proposed that they had finally found the culprit only only one key change seemed to match up with The Disappearance of Nautilus fossils from any location and that's the arrival of pinnapet which are seals and their relatives now pinnipedes evolved from terrestrial ancestors in the order Carnivora that became what we call secondarily Aquatic and the details of who exactly these ancestors were and how their return to the water happened are kind of murky there are still some big gaps left to fill in that story but we do know that by about 28 million years ago the earliest recognizable pinniped relatives had begun splashing through the water like an Ali arctos for example A genus that contained several extinct species with clear adaptations for swimming whose fossils have been discovered in coastal Oregon and California and as the researchers tracked the spread of pinnipeds to new coastal regions around the world they saw the same pattern again and again whenever they arrived nautiluses vanished until by the pliocene Epic around 5 million years ago Nautilus fossils were gone from everywhere apart from Deep tropical waters of the indo-west Pacific an area notable today for you guessed it not having any native pinnipeds okay but it's not like pinnipeds were the first predatory group that nataloids have had to contend with right they weren't even the first mammalian Marine Predators whales had already returned to the water millions of years earlier and the emergence of a few short snouted and toothed ancient whale groups did match up with the local disappearance of nautiloids from an area but that was a blip compared to the global Trend that the researchers saw later with the arrival of pinnipeds so why were whales less of a problem for the nautiloids than seals well the researchers proposed that it came down to their different eating strategies some some whales are and were much bigger than pinnipeds so nautiluses were either too small to be a worthwhile snack for them or they were filter feeders other groups like The basilosaurids might have Incorporated them into their diets but still didn't seem to have affected the nautiluses much upon arriving on the scene and we really don't see modern whales eating nautiluses today either this is probably because getting them out of their shell takes a different kind of feeding strategy than whales usually use pinnipeds on the other hand excel at that task their so-called Pierce feeding technique allows them to catch prey with their sharp teeth and then use suction or vigorous shaking to extract it from its shell ancient seal fossils also have features of their skulls and teeth that suggests they could do this too so it looks like they'd appeared with just the right tools to end the reign of the nautiloids the researchers found that only one group seems to have been able to at least temporarily hold out against the arrival of pinnipeds in the oligosian Epic a Genus called atturia they were the athletes of the nautiloid world with adaptations for especially fast and agile swimming plus they seem to have had an unusually rapid reproductive cycle and these traits seem to have allowed species of a turia to survive for a while at least even after the other species of Nautilus had been pushed out buturia stuck around until the end of the myocene Epic around 5 million years ago but eventually their fossils vanished too not just from most coastal regions but globally so what happened to atturia well the researchers proposed that they could run but they couldn't hide siatoria was faster and more agile than your average nautiloid sure which gave them a short-term advantage in coping with the arrival of seals by simply being harder to catch but that also came with a trade-off they're thinner lightweight shell meant that they couldn't swim as deep as other groups so while the ancestors of modern nautiluses were able to retreat to Greater depths atoria just couldn't follow them to safety and from the extinction of Vittoria until now the oceans have been almost totally not alloyed free for the first time in around 500 million years safe for the species that still thrive in the last seal free Paradise for now the Marine realm is after all not so different from the terrestrial realm and like a flightless bird on an island having to deal with the sudden arrival of a new Predator if pinnipeds were to expand their range nautiluses might find themselves with nowhere left to run this all goes to show that ancient doesn't mean Invincible changes of Fortune can happen to any group even one that's been a constant presence in ecosystems for hundreds of millions of years because nature is at heart pretty chaotic from the Nautilus is unprecedented chaos might just look a lot like seals [Music] okay so if you're a fan of cephalopods check out our episode where are all the squid fossils to find out why squids are the exception to the great cephalopod fossil record and thanks to this Muncie ontologists who get our seal of approval Gail Brown Juan in Jackson Weiss Melanie Lam Carnival Rafael Haas Annie and Eric Higgins John Davidson ing Jake Hart and Colton by becoming an eni at patreon.com eons you can get fun perks like submitting a joke for us to read here's one from Dara who is an idiacaran's favorite poet Emily dickinsonia that was a good one I like that one that one's really good okay dick and Sonia and as always thanks for joining me in the Adam Lowe Studio subscribe to youtube.com eons for more creature features have been a constant presence for presence presence I'm gonna drink some try and uh on a reset who reads for work me hmm

Channel: PBS Eons

Views: 580,199

Keywords: nautiloid, nautilus, nautiluses, seals, pinniped, cephalopods, Enaliarctos, pierce-feeding technique, Aturia, predator, natural history, evolution, paleontology

Id: 3vQ55ToQeWI

Length: 11min 3sec (663 seconds)

Published: Tue Mar 28 2023