Bloggers Wanted
We're looking for people to help with the main blog. If you are consistent, knowledgeable and you're into it, please drop me a note.
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Grokker
 Senior Boarder
Posts: 75 
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I am interested in finding the best estimates, based on stratigraphy, for time of divergence of land vertebrates from teleost fishes and the time of appearance of the chordates. The numbers that I have found are 350 and 620 MYA respectively.
Mike Syvanen
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Julie2007
Senior Boarder
Posts: 60
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Um, the divergence of land vertebrates from teleost fishes didn't quite happen like that. What are you actually looking for? The divergence of tetrapods from other sarcopterygians? Teleosts are the most derived form of actinopterygian fishes, and actinopts are high up on the fish phylogenetic tree. The land-dwelling tetrapods came from the midst of the sarcopterygian fishes - if you're interested look for papers by Per Ahlberg - he's done a lot recently on the exact phylogeny of the fish-tetrapod transition.
Becky
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gsbisht1
Expert Boarder
Posts: 88
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Teleost fish and land vertebrates once shared a common ancestor. The lineages split at some time in the past and one line led to modern fish and the other to mammals etc. What was the age of the last common ancestor? I am not particularly interested in the exact phylogeny at this time.
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Grokker
Senior Boarder
Posts: 75
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Jennifer Clack in her recent book - Gaining Ground - puts earliest undoubted tetrapods in Famennian (~365 Mya) though some fossils from Frasnian (~375 Mya) could be tetrapods.
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