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RE: Polish find in Nature
>How reliable is the trackway dating?
Unambiguously lower Eifelian. (refs 40-45 in the Nature Paper)
>How reliable is the dating of tiktaalik?
Unambiguously Frasnian based on palynomorph data. Plus it should be noted that
more derived (tetrapod-like) fishapod Livonia existed long before Tiktaalik.
>It seems odd to me that tiktaalik would exist in the presence of fishapods
>with better developed limbs, but that may just be >my inability to conceive of
>a niche that would favor the development of stubby leg like fins over "true"
>limbs or "true" fins.
Not just "fishapods with better-developed limbs" - full blown
look-at-my-fingers Tetrapoda were crawling about out of the water in the
earliest Mid Devonian. Note that the Wojciechowice trackways are in a very
different depositional setting to all other fishapod and Famennian
stem-tetrapod sites - a marine tidal flat environment devoid of terrestrial
vegetation as opposed to a swampy, vegetation-rich freshwater setting (ie.
Middle Devonian tetrapods occupied different niches to Middle Devonian
fishapods). There is no evidence as yet for tetrapods in freshwater habitats
until at least Givetian and they did not become common until the Famennian
leaving plenty of room for Tiktaalik and kin.
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