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Boesse posted a topic in General Fossil DiscussionHey all! This week my colleagues and I published a paper we spent most of the last decade sweating over. It is an exhaustive report of all known late Miocene-Pleistocene records of teeth of Otodus (aka Carcharocles) megalodon teeth from the west coast in an attempt to estimate the date at which O megalodon went extinct. Aside from some conspiracy theorists who will wait until they die and not see a live 'meg', we all know it's not living today as there is not a shred of positive evidence indicating its existence. We know it's around in the Miocene, and the early Pliocene. Did it survive into the Pleistocene? End of the Pliocene? or become extinct sometime earlier? These questions require serious thought because it has direct implications for whether or not O. megalodon went extinct at the same time as a bunch of weird marine mammals or if it was killed off by a supernova known to have occurred 2.6 Ma. An earlier study pooled fossil occurrences from around the globe and statistically reconstructed a mean extinction date of 2.5 Ma, with significant error (~3.6 Ma to 100ky in the future being the max and min extinction dates). We found that in the California record, reliable occurrences are only found in early Pliocene rocks. All examples of late Pliocene or Pleistocene teeth were either poorly dated, reworked from Miocene rocks, had poor provenance, or are completely missing (and never photographed) and therefore the identification cannot be confirmed. We thus predicted a 3.6 Ma extinction date. To test this, we re-analyzed the dataset published in 2014 but chucked a bunch of bad data and exhaustively re-researched the stratigraphy of each locality and corrected about 3/4 of the dates in the remaining dataset, and added our new California records. When we analyzed this corrected dataset, our margin of error (the time between the max and min extinction dates) shrank from 3.6 million year long interval to 900,000 years; *probably* extinct by 3.6 Ma (mean extinction date), definitely by 3.2 Ma (min extinction date), and possibly as early as 4.1 Ma (max extinction date). This extinction therefore precedes the 2.6 Ma supernova, as well as the Plio-Pleistocene marine mammal extinction (which in all likelihood was not a mass extinction or an extinction event, rather just a period of higher extinction/origination rate). About 4 Ma is when fully serrated Carcharodon carcharias teeth show up in the North Atlantic, indicating when the two overlapped, however briefly. We think this biotic event matches best - the mechanics of exactly how this was driven are to be figured out by someone else, but perhaps adult Carcharodon outcompeted juvenile O/C megalodon prior to becoming gigantic. Some analyses of Otodus lineage growth rate is going to be necessary. Here's the open access paper here: https://peerj.com/articles/6088/ Here's a blog writeup I did for PeerJ here: https://peerj.com/blog/post/115284881293/early-pliocene-extinction-of-the-mega-toothed-shark-otodus-megalodon-boessenecker/ Excellent summary in Nat Geo: https://www.nationalgeographic.com/science/2019/02/megalodon-extinct-great-white-shark/ CNN: https://www.cnn.com/2019/02/14/us/megalodon-extinct-earlier-scli-intl/index.html Fox News: https://www.foxnews.com/science/megalodon-shocker-huge-killer-shark-may-have-been-wiped-out-by-great-whites Forbes: https://www.forbes.com/sites/melissacristinamarquez/2019/02/14/great-white-sharks-may-be-the-reason-why-giant-megalodon-shark-is-extinct/#6a06986a6486 Daily Mail: https://www.dailymail.co.uk/sciencetech/article-6700495/Giant-50-foot-long-predatory-shark-went-extinct-one-million-years-earlier-previously-thought.html