Can someone point me to a nice RECENT summary of the functional
morphology of heterocercal versus hypocercal tails in early fish?
Can someone explain to me the functional significance of why
Hemicyclaspis has a heterocercal tail and
Drepanaspis has a
hypocercal tail when both fish are ventrally flattened and appear to have
been benthic bottom-dwellers (or is that idea outdated?)? The
literature seems a little confused on this subject. I have found
seemingly contradictory claims: heterocercal tails are typical of
bottom-dwelling creatures because it provides a downthrust and keeps the
lower lobe from dragging through the mud, whereas as hypocercal tails
(such as in
Pteraspis) provides upward thrust. If this is
true why is the tail of
Drepanaspis hypocercal? Wouldn't the
lower lobe drag through the mud and move the animal away from the
substrate?
A confused invertebrate paleontologist who is getting frustrated with
"just-so-stories"....
;) Alex
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Alexander Glass
Assistant Professor
Central Washington University
Department of Geological Sciences
400 East University Way
MS 7418
Ellensburg, WA 98926-7418
United States
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Tel: 1-509-963-2192
www.geology.cwu.edu/facstaff/glassa
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