The Great Snake Debate

PBS Member Stations rely on viewers like you. To support your local station, go to http://to.pbs.org/DonateEons ↓ More info below ↓ 90 million years ago, an ancient snake known as Najash had...legs. It is by no means the only snake to have limbs either. But what’s even stranger: we’re not at all sure where it came from. Produced for PBS Digital Studios. Thanks to Franz Anthony, Julio Lacerda and Studio 252mya for the snake illustrations. You can find more of their work here: Julio Lacerda: https://252mya.com/gallery/julio-lacerda Franz Anthony: https://252mya.com/gallery/franz-anthony Want to follow Eons elsewhere on the internet? Facebook - https://www.facebook.com/eonsshow Twitter - https://twitter.com/eonsshow Instagram - https://www.instagram.com/eonsshow/ References: http://www.wienslab.com/Publications_files/Wiens_et_al_Evolution_2006.pdf Locomotion in sea snakes: http://onlinelibrary.wiley.com/doi/10.1046/j.1420-9101.2001.00265.x/pdf Ear bones in mammals: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3552421/ Skinks: https://www.livescience.com/3053-evolution-action-lizards-losing-limbs.html Pachyrhachis lifestyle: http://www.tandfonline.com/doi/abs/10.1080/08912969909386578 Snake defining features: https://www.ucl.ac.uk/museums-static/obl4he/vertebratediversity/serpentes_snakes.html Hsiang & Field 2015 Summary: https://blogs.biomedcentral.com/bmcseriesblog/2015/05/20/limbless-triumph-origin-diversification-snakes/ 2012: Zaher at al. think Dinylisia is a sister taxon to all extant snakes: http://onlinelibrary.wiley.com/doi/10.1111/j.1096-3642.2011.00755.x/abstract 2015 news story on Tetrapodophis: https://www.sciencemag.org/news/2015/07/four-legged-snake-fossil-stuns-scientists-and-ignites-controversy Another 2015 story on Tetrapodophis: http://phenomena.nationalgeographic.com/2015/07/23/a-fossil-snake-with-four-legs/ 2015 news story on Eophis: https://www.scientificamerican.com/article/remarkable-fossils-push-back-snake-origins-by-65-million-years/ 2017 thesis on mosasaurs that makes it quite clear that there’s still quite a bit unresolved in the evolutionary relationships: https://era.library.ualberta.ca/files/c4x51hj54w#.WiXVU9WnG3A varanids (monitor lizards): http://animaldiversity.org/accounts/Varanidae/ Coniophis (65 million years young): https://news.yale.edu/2012/07/25/few-bones-most-primitive-snake-emerges Toxicofera paper: https://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-13-93#Sec2 See the "Bitter Realities about Squamate Phylogeny" section on this page: https://www.geol.umd.edu/~jmerck/geol431/lectures/17blepidosauria.html Tetrapodophis actually aquatic?, paper proposes: http://www.sciencedirect.com/science/article/pii/S0195667116301094 2013 paper w/the 4000 species: https://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-13-93#Sec2 file:///home/chronos/u-e54db2a63a5b8e4345d3372e31d0632282c76ec5/Downloads/apestiguiazaher_nature06-0001.pdf https://www.nature.com/articles/nature04413 2017: Norisophis http://www.sciencedirect.com/science/article/pii/S0195667116302014 Nidophis: http://www.bioone.org/doi/abs/10.1080/02724634.2013.764882 Coniophis: https://blogs.scientificamerican.com/observations/first-prehistoric-snake-slithered-out-on-land-not-at-sea/ https://www.livescience.com/27845-snakes.html http://www.sciencedirect.com/science/article/pii/S0195667116301094 https://www.ucl.ac.uk/museums-static/obl4he/vertebratediversity/serpentes_snakes.html https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3552421/ https://watermark.silverchair.com/j.1096-3642.2009.00511.x.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAdAwggHMBgkqhkiG9w0BBwagggG9MIIBuQIBADCCAbIGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMRzwNfprt0x5FaRYBAgEQgIIBg6jXei7ktTZ6OT9JEIBHqHcP6NWoN8ZQ3V8_8f66h9XGJCbZJFE-HpZlZe3ABqOsTfbKwzTP81PkIXEWg8HsNOPU_tmhudWMaIfEgvXSQmB4qvJzcsn3yORkxFW6-X3qxh59JsBP-Na4UvRKMOKFUckpX4ugYYEUkunPbG6Tb0a-h_EaaerhpTFAJfihmZ6rEd1ebBgO09AtOmtNNR61TCts3zl3efZILYC-UsonaXe-XIea5HQg5MzVb5Ye3iXbc57hDH6p0t99RTVwCVtFasUXVqpxT0Oyx0oAIjD_vrn9-_DpRCKzgEmrEGOddLVypCn_p5H07a3nucJMqBhQ4xHE8bBVIKVHjDLdLH1yQIW2Fh5pFHZPB-6ONI3TFQ68EZnHHf2o9IywK3s_3vrHn8IXFnAEI7xKLHvTzPr7F8f_UGcAbyV6ryMH_Mz9JjE90mlMvEHjFRqnxFxaR9zHv3ETHDYE-jenctA74ec4XX2pxkpFSPOf2bmWqXncoCxkxKz9wA http://www.tandfonline.com/doi/abs/10.1080/08912969909386578 https://blogs.biomedcentral.com/bmcseriesblog/2015/05/20/limbless-triumph-origin-diversification-snakes/