Researcher finds missing link between ancient toothed whales and modern baleen whales

Aug 18, 2011 by Bob Yirka report
Evolution of mysticete skull features linked to feeding, based on the phylogeny in the study of Fitzgerald. Cetacean artwork by C. Buell. Image (c) Biology Letters, doi:10.1098/rsbl.2011.0690

(PhysOrg.com) -- Erich Fitzgerald, an Australian paleontologist, believes he has found the missing link between ancient toothed whales that caught and ate fish and modern baleen whales that eat by sucking in huge volumes of water and then filter out the krill and shrimp in it.

In his paper, published in the Royal Society journal, Biology Letters, Fitzgerald describes the of Janjucetus hunderi, named for the beach where the original was found; "cetus" Greek, for whale and Staumm Hunder, the youngster who found the fragment. More recently, Fitzgerald discovered that amateur Brian Crichton had more such bones enabling him to build a more complete picture of the ancient (25 million year old) creature.

Fitzgerald suggests that modern , a class of whales that use a filter called a baleen to filter food from sea water, evolved from toothed fish eaters to the modern giants we now see, via the Janjucetus, a creature about the size of a contemporary dolphin, but one that had a very different jaw structure.

Baleen whales, a class that include the , the largest animal known to have ever existed, have a jaw that is not fused in front, allowing it to flex and expand so that it can draw in huge amounts of water when lunging at a mass of . Ancient whales on the other hand, had jaws very much like dolphins, or even humans for that matter. They opened their mouths and grabbed fish swimming by, using their teeth as mini harpoons, much as do today. Janjucetus falls somewhere in-between; it has a jaw that is fused in front but the upper jaws are inordinately wide, and its snout is short. Also, its mouth is proportionately big for its body.

Fitzgerald theorizes that all of these characteristics put together indicate that Janjucetus captured and ate its prey differently than both its early ancestors and its modern counterpart. Instead of grabbing fish as they came by, Janjucetus sucked in the water surrounding them, pulling them in with it, then chomped down to capture them.

It’s this early sucking, or “hovering” as Fitzgerald describes it, that after several million years, led to the un-fusing of the jaw, the gradual loss of teeth and the appearance of the baleen.

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More information: Archaeocete-like jaws in a baleen whale, Biology Letters, Published online before print August 17, 2011, doi:10.1098/rsbl.2011.0690

Abstract
The titanic baleen whales (Cetacea, Mysticeti) have a bizarre skull morphology, including an elastic mandibular symphysis, which permits dynamic oral cavity expansion during bulk feeding. How this key innovation evolved from the sutured symphysis of archaeocetes has remained unclear. Now, mandibles of the Oligocene toothed mysticete Janjucetus hunderi show that basal mysticetes had an archaeocete-like sutured symphysis. This archaic morphology was paired with a wide rostrum typical of later-diverging baleen whales. This demonstrates that increased oral capacity via rostral widening preceded the evolution of mandibular innovations for filter feeding. Thus, the initial evolution of the mysticetes' unique cranial form and huge mouths was perhaps not linked to filtering plankton, but to enhancing suction feeding on individual prey.

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User comments : 13

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kevinrtrs
1 / 5 (20) Aug 18, 2011
It's really sad when you see how people have to lie to themselves to make a story fit in with the evolutionary mythology.
There is unfortunately no way for the researcher to confirm that those changes from one fish did in fact occur. There was no one there to record that change and there are no great number of missing links that have been found between this one and the ultimate baleen whale. The researcher is on a hiding to nothing.
Fitzgerald's theory will have to remain as it is: an unsubstantiated theory which cannot be falsified either since the same non-witnessed argument can be applied.
It might be better to postulate that the fish were created that way. The same validation or non-validation can be applied but the explanation just fits better since there are only two discreet, non-interlinked specimens/objects to be observed - with no further physical evidence available to draw his conclusion.
Y8Q412VBZP21010
5 / 5 (4) Aug 18, 2011
Oh AARGH ... they had to put "Missing Link" in the title?

"Common ancestor", please, and even that's a bit misleading.
Ben_Levy
not rated yet Aug 18, 2011
Very interesting!
But it's not "hovering", which is what helicopters due, it's "Hoovering", named after the vacuum cleaner.
Peteri
4.5 / 5 (8) Aug 18, 2011
@kevinrts: Likewise, using your logic, you were not around to witness your chosen deity supposedly creating the universe 6000 years ago and so all you have to rely on are dubious calculations based on time-lines derived from collected stories in your religious texts.

It would appear that you and like-minded people have built your creationalist house on sand rather than founding it on rocks as paleontologists have done!
Ben_Levy
4.3 / 5 (6) Aug 18, 2011
@kevinrts: fish? Lost you there.
But evolution, like any good science, can be tested, even if it is not "witnessed". You test the predictions. For example, in the case of whales, we can say "I believe these whales descended from the toothed whales, and therefore I predict that an analysis of the proteins coating their red blood cells will reveal approximately the number of divergences we can predict from bifurcation of the gene pool X million years ago". Now, if these animals were all "created" there would be no reason for a baleen whale's blood cells to be comparable to a toothed whales. They could easily more closely resemble the blood cells of a walrus or even a penguin! And to expect that the detectable, countable, accumulated genetic drift revealed by those proteins would match the mathematical models, that would be just too much! But we can look, and we can compare genes... and guess what we find? Our discoveries support our predictions. Testable.
Guy_Underbridge
4.5 / 5 (8) Aug 18, 2011
It's really sad when you see how people have to lie to themselves to make a story fit in with their religious mythology.


Fixed that for you
grosyhpgrosyhpgrosyhp
5 / 5 (4) Aug 18, 2011
It might be better to postulate that the fish...

@kevinrtrs, you are creationist! No doubts)
badger1966
5 / 5 (1) Aug 19, 2011
One wonders if there is someplace on this Earth where one can avoid religious extremists. Wonder if there are this many Flat-Earthers in Germany.

Other than that, interesting article. Fills in a piece.
Silverhill
5 / 5 (5) Aug 19, 2011
It's really sad when you see how people have to lie to themselves to make a story fit in with ... mythology.
Yes, very sad indeed.

changes from one fish
Fish mammal. Be careful--your ignorance is showing (again).

There was no one there to record that change
Or the creation that you allege.

The researcher is on a hiding to nothing.
He has company in you, then.

It might be better to postulate that the fish were created that way. The same validation or non-validation can be applied but the explanation just fits better ... with no further physical evidence available to draw his conclusion.
Mr. Pot, do be careful in how you describe Mr. Kettle! (For the literature-impaired: kevinrts claims a lack of physical evidence, while proffering none to support his side.)
Silverhill
5 / 5 (3) Aug 19, 2011
correction to above, since the "not equals" symbol did not show up: "fish does not equal mammal"
Sinister1811
2.5 / 5 (11) Aug 19, 2011
@Kevinrts Evolution isn't mythology. It's been proven time and time again. Especially by those studying fossils, examining the missing links between species. By looking at fossils you can see the gradual changes from one species to another over millions of years. Species change and adapt to different conditions over time, as different mutations occur in different gene pools. It's not really mythology.
Y8Q412VBZP21010
5 / 5 (2) Aug 19, 2011
Kevin just comes to PHYSORG to moon people. He issues his standard re-runs of verbiage, collects 1-star votes, and snickers because he has accomplished his mission of being annoying.

And he cannot lose any credibility doing it, because he's never had any credibility and doesn't want any credibility. He'll be playing the same games when he's 80, and still snickering.
aroc91
not rated yet Aug 20, 2011
Thanks for conforming to the stereotype, kevin. lol

Missing links are being found and yet you're denying their relevance. Typical.

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