Whale in action: Whale watching off the coast of Iceland
Courtesy Jake RyanRecently discovered fossils of a previously known species of early whale called Georgiacetus vogltlensis are giving new insight into how whales eventually developed tail flukes.

Paleontologist Mark D. Uhen of the Alabama Museum of Natural History at The University of Alabama found the fossils in Alabama and Mississippi. Georgiacetus lived 42 million years ago during the Eocene epoch. It was about 11 feet in length and had four limbs, although its rear leg bones weren’t attached to its body and were probably worthless for walking. (The Buzz's ARTifactor covered an earlier story about whales and their legs you can view here).

The new fossils contained previously unknown bones in Georgiacetus’s tail region. Study of the additional tailbones show that the whale ancestor had no fluke. It did, however, have large back feet, and appears to have propelled itself in much the same way modern whales do by undulating its hips in a wave motion.

"When whales move their flukes through the water, it creates a force to move them forward. Georgiacetus is doing something similar with its feet,” Dr. Uhen said.

Swimming vertebrates employ a number of swimming methods, such as paddling with all four limbs, paddling with only the back limbs, tail wiggling, and tail oscillation, and undulation of the hips. The last method – hip undulation - was thought to have been skipped by whales during their evolution, but this new fossil evidence shows otherwise.

The Journal of Vertebrate Paleontology published Uhen’s study in its recent issue.

LINKS
Story in JVP
Story on Fossil Science
Fox News story
Lots of links about whales and whale evolution

Tags : whales, whale evolution, evolution, adaptation, marine biology, fossils, paleontology

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For decades, scientists have been growing microbes in their labs and watching them evolve new traits. Most of the changes tend to be simple things, like an increase in size or growth rate.

But Dr. Richard Lenski of Michigan State University (just 2 miles from my house!) recently witnessed a major evolutionary leap--as it was happening. Twenty years ago, he took a colony of E. coli, a common bacteria, and split it into 12 identical populations. He’s been watching ever since to see if the strains evolve in different directions.

A few years ago, one of them did. One of his study strains suddenly evolved the ability to eat citrate, a molecule found in citrus fruits. No other E. coli in the world can do this, not even the other strains in Dr. Lenski’s lab. Even given several extra years and thousands of extra generations, the other strains are still citrate-averse. What’s more, the bacteria evolved this mutation entirely on their own, without any prodding or genetic manipulation from the researchers.

Lenski had saved frozen reference samples of all of his strains at regular intervals. Going back and growing new cultures from these samples, he again finds that only those from one strain ever evolve the citrate-eating habit – and only those sample less than about 10 years old. Lenski figures that some mutation happened around that time in one strain – and one strain only – that would later lead to citrate eating. He and his lab are now working on figuring out exactly what that mutation is.

Tags : evolution, bacteria, E. coli, adaptation, heredity, genetics

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