Mammalodon and Modern Baleen Whales

Mammalodon Facts: Whale Fossil Unlocks History of Early Mysticeti Evolution

New research out of Australia helps paleontologists shed light on the cloudy history of the evolution of the early baleen whales.

The Museum Victoria of Victoria, Australia is presently home to some exciting research into the history of Mysticeti, more commonly known as baleen whales (as opposed to Odontoceti, or toothed whales). While much research has gone into the evolutionary history of Cetacea (whales), relatively little is solidly in place in science textbooks. Now, however, a little light has been shed on the baleen giants.

Leading the research at the Museum Victoria is Dr. Erich Fitzgerald, a paleobiologist who is now focusing efforts on studying the fossilized Mammalodon colliveri, one of the earliest fossilized examples of a baleen whale ancestor.

The Early Baleen Ancestor, Mammalodon

The 25-million-year-old Mammalodon colliveri was discovered long ago, in 1932, and was, for lack of better phrasing, pushed to the paleontological back burner for a number of years. Little was known about the creature for a long while, but Dr. Fitzgerald has now brought the surprisingly small whale back into the spotlight.

Mammalodon measures almost 10 feet in total body length, which is remarkable considering it is suspected to be one of the earlier ancestors of the largest living mammal, the blue whale. In fact, the blue whale is believed to be the largest animal – not just mammal – to ever have existed. Mammalodon, at only 10 feet, seems an unlikely predecessor.

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It is, of course, not the size that relates Mammalodon to the blue whale; it is rather the nature of its teeth. The early baleen relative did not only possess a mouth full of baleen, but was toothed as well. This combination helps researchers like Fitzgerald understand the potential causes for whales to have evolved the baleen in the first place.

Based on the dental structure of the animal, Fitzgerald believes that Mammalodon was likely a bottom-feeding whale, sucking through mud, sand, and another sea-floor terrain to find its prey. Mammalodon seems to have been built for this kind of hunting, judging not only from its primitive baleen but also because its nose is short and blunt. Baleen may have arisen through the years in order to assist in this type of hunting, negating eventually the need for teeth.

Mammalodon, Then and Now

Mammalodon belongs to a family that also includes Janjucetus hunderi, another 25-million-year-old whale that is a likely ancestor to extant baleen whales, although Janjucetus lacked baleen altogether. Both whales were discovered near Victoria, Australia, leading Fitzgerald to believe that Australia was the place to be for these strange, Oligocene whales.

The fossils from the small Mysticete Mammalodon will be on display at the Melbourne Museum on December 22, 2009, and Dr. Erich Fitzgerald’s full paper on his findings regarding Mammalodon is now published online at Wiley InterScience.

Resources:

Erich M.G. Fitzgerald. The morphology and systematics of Mammalodon colliveri (Cetacea: Mysticeti), a toothed mysticete from the Oligocene of Australia. Zoological Journal of the Linnean Society, 2010; DOI: 10.1111/j.1096-3642.2009.00572.x

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Museum Victoria (2009, December 22). Fossil Unlocks Secrets. Retrieved December 23, 2009.

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