We will also be presenting on some preliminary findings from this work at the IV Congreso Latinoamericano de Paleontología de Vertebrados, in San Juan, Argentina. Check out it out the meeting homepage or, better yet, see you in Argentina.
What does an ancestor of today's baleen whales look like, some 24-27 million years ago? Probably something a bit like this:
Erich Fitzgerald, in 2006, with the type specimen of Janjucetus. Credit: Museum Victoria
In 2006, my colleague Erich Fitzgerald dropped a bombshell on the rest of paleocetology. In a sole-authored paper published in Proceedings of the Royal Society B (written while he was a graduate student at Monash University), he described an entirely new kind of early baleen whale from the Oligocene of Australia: Janjucetus hunderi, with anatomical features nearly unlike any putative early baleen whale reported at the time. (Larry Barnes, now emeritus curator of vertebrate paleontology at the Natural History Museum of Los Angeles, remarked to me at the time, with wild eyes, "That things looks like a horse!"). In fact, without close inspection of its ear bones and skull, you wouldn't be wrong for thinking it was an odontocete. Or a plesiosaur. Based on Erich's analysis, Janjucetus actually fit in very close to the base of the mysticete family tree, leading to some startling ideas about how many hallmark baleen whale traits evolved in the first place.
A 2011 reconstruction of Janjucetus by Carl Buell.
Anything from the Oligocene is interesting for fossil marine mammalogists because we have so little fossiliferous marine rock outcrops, globally, from this period of time, which covers episodic sea-level lows following the onset of Southern Hemisphere glaciation. The fact that Janjucetus came from the Oligocene of Australia was even more enigmatic (though, not without precedent). Curious readers can read more about in Carl Zimmer's excellent piece.
Today Erich reports on more information about Janjucetus in today's Biology Letters. Based on an incomplete lower jaw representing additional material of this early whale, Erich describes how Janjucetus possessed lower jaws that were fused at the tip (near the mandibular symphysis), unlike every single previously described baleen whale (fossil or modern), but very much like the condition we see in the ancestors of today's whales (the so-called "archaeocetes"). The implication of this find is that the earliest baleen whales were feeding using a mode unlike their descendents, who have much more mobile jaws. Carl Zimmer provides another great take; see also these news reports (ScienceNOW/AAAS and BBC news), which include comments from lab members and associates.
Friend of the show Jeremy Goldbogen is doing fieldwork this summer off the coast of California, tagging blue whales and other large cetaceans as part of his postdoctoral work with Cascadia Research Collective. His work with his colleagues is revealing the fine-scale underwater movements and behaviors of large cetaceans, which has implications for understanding their ecology, physiology and evolution, too. (See Jer's publications, for more details).
Two blue whales just off the southern California coast (J. Calambokidis, Cascadia Research. Taken under NMFS permit #14534).
You can follow Jeremy and his colleagues, as they live blog from their research vessel, right offshore at SEA Blog:
In the last few days we have had a number of our suction cup acoustic tags slide around and ultimately off blue whales that we have tagged. This isn't new or entirely unexpected, given that these animals, like all cetaceans, shed layers of skin quite rapidly. Attaching anything to animals that have had tens of millions of years to become streamlined to live and move in water is no trivial feat, especially with suction cups on animals shedding skin. We have managed to overcome this in many instances and have gotten a large amount of data already in the first full week of SOCAL-11, but we have lost a few tag attachments with tags sliding off.