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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
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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/
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