Friday, January 8, 2010

Random bits #6

It snowed again here in east Tennessee. Twice in one winter. That's unusual. While I wait for the sun to come up so I can decide when I'm going to work, here's another installment of random articles that struck my fancy.

First up, the Zoological Journal of the Linnean Society has an article by Fitzgerald on the fossil whale Mammalodon. It was brought to my attention by the ScienceDaily headline "Australian Fossil Unlocks Secrets to the Origin of Whales", which might lead one to believe that it was another intermediate form between land mammals and whales. It's not. Mammalodon is just a funny-looking toothed mysticete, which is a kind of intermediate. Living whales can be divided into toothed whales (odontocetes) and baleen whales (mysticetes). The fossil record shows that mysticetes with teeth actually existed in the past, and Mammalodon is one of them. My own research on toothed mysticetes implies that they aren't in the same baramin as modern mysticetes but instead group with the archaeocetes, an Eocene group of whale-like animals with hind legs. I haven't evaluated this new Mammalodon information carefully yet, but I will. In any case, it's an interesting fossil.

Weir et al. have an interesting piece on the Great American Biotic Interchange in birds. Fossil and tectonic evidence indicate that North and South America were once separate continents until the recent formation of the isthmus of Panama. Once Panama formed, land animals from the previously isolated continents could mingle, and marine creatures on either side of the isthmus were cut off. The fossil record indicates that most of the movement of land animals went from the north to the south, and many South American forms went extinct. Weir et al. tested whether the Biotic Interchange could be detected in birds using molecular clocks. They found evidence of the Interchange in forest birds that do not disperse across water, which one could interpret as further support for the recent formation of Panama and the Great American Biotic Interchange.

And Reidenbach et al. have a new phylogenetic analysis of mosquitos. This is interesting to me only because of that old joke about why didn't Noah swat the two mosquitos when he had the chance. Maybe they weren't bloodsuckers back then? I don't know.

Well, it's 7:20 here, and the sun should be close to rising now. I think I'll check the snow in my yard, and maybe I'll get ready for work. Or maybe not.

Fitzgerald. 2009. The morphology and systematics of Mammalodon colliveri (Cetacea: Mysticeti), a toothed mysticete from the Oligocene of Australia. Zool J Linn Soc

Reidenbach et al. 2009. Phylogenetic analysis and temporal diversification of mosquitoes (Diptera: Culicidae) based on nuclear genes and morphology. BMC Evol Biol 9:298.

Weir et al. 2009. The Great American Biotic Interchange in birds. PNAS 106(51):21737-21742.