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Whales Had Legs, Wiggled Hips, Study Says


Guest Nicholas

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...and it was student-collected fossils from Coffeeville Alabama that lead to the finding.

Way to go, kids!

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

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Quite a bit is known for archaeocete evolution, but Georgiacetus is the most completely known early Archaeocete - its skeleton is more complete and much more well preserved than Ambulocetus, which is usually thought of as the most complete early archaeocete.

In any event, the hindlimbs of Georgiacetus point to parasaggital undulation of the hindlimbs (parasaggital = up/down, or in anatomical terms is equivalent to dorso-ventral movement; the saggital plane splits a vertebrate body in half and is the axis of symmetry; so parasaggital means along that plane; undulation is just a back and forth movement).

The neat thing is that most terrestrial mammals (including artiodactyls, from which whales evolved) do not swim in this manner; they do more of a 'doggy paddle' that is similar to the pattern of leg movement on land.

The neat implication is that Protocetids had already moved away from this pattern and toward up/down movement, which later evolved into a bigger tail with a caudal fluke.

Bobby

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"The neat implication is that Protocetids had already moved away from this pattern and toward up/down movement, which later evolved into a bigger tail with a caudal fluke".

So, having already moved away from "doggy paddle", must mean there is still a long way to go to find the earliest forebears.

KOF, Bill.

Welcome to the forum, all new members

www.ukfossils check it out.

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So, having already moved away from "doggy paddle", must mean there is still a long way to go to find the earliest forebears.

Well, possibly, depending on your definition of forebears. There are already several genera of well preserved Pakicetids, Remingtonocetids, and Ambulocetids that have already been described in gory detail; these are all more primitive than Protocetids.

And, for example, Pakicetus inachus is known from a nearly complete skeleton, and the only whalelike part is the head; the rest of the skeleton is still adapted for running on land and not too different from other terrestrial artiodactyls. Other pakicetids and some remingtonocetids show slightly more aquatic adaptations, and Ambulocetus is more or less transitional in its biomechanics and aquatic adaptations between Pakicetids and Protocetids.

So, there are pretty well defined transitions for most aspects of cetacean anatomy. Every new find is just filling in currently missing pieces; this study is an example.

The real remaining mystery is what extinct group of artiodactyls gave rise to whales? There are several good candidates, but ultimately, more early Eocene artiodactyls and cetaceans need to be dug up in order to bridge that 'gap'.

Bobby

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Right, got ya.

But this I what I mean by "earliest"

"The real remaining mystery is what extinct group of artiodactyls gave rise to whales? There are several good candidates, but ultimately, more early Eocene artiodactyls and cetaceans need to be dug up in order to bridge that 'gap'".

KOF, Bill.

Welcome to the forum, all new members

www.ukfossils check it out.

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