Daily Archives: November 16, 2007

Global Warming, the Blog Epic ~ 02 ~ Greenhouse Effect, Greenhouse Gas

This is the second in a series of reposts from gregladen.com on global warming. i-e1372cd57ce206dff3631a4a9438e737-epic-GlobalWarming.jpgWhy Greenhouses have nothing to do with the Greenhouse Effect, and more importantly, why CAN’T I microwave toast?A greenhouse is a glass house that is sealed to keep air in and insulated to keep heat in but at the same time allow sunlight in. This sunlight contributes to the heat in the greenhouse by warming the ground or other material in the greenhouse, and of course the light energy is used by the plants. But the point of a greenhouse is to keep air that is warmed, by the sun and/or heaters that may be required in the greenhouse, from wafting away.This is not how the so-called “greenhouse” effect works. There is no thing out there keeping warm air from wafting away from the planet. The air just stays there, greenhouse effect or not, moving around and doing the weather thing, and looking blue much of the time. Continue reading Global Warming, the Blog Epic ~ 02 ~ Greenhouse Effect, Greenhouse Gas

Intelligent Design

Here is a preliminary list of resources for people to find out more about Intelligent Design. Please feel free to put this on your own site. If you want, email me and I’ll send you the HTML code to make this one step easier. But you can also, if you are using Firefox, use “ctrl-u” to display the code and cut and paste it from there.Please feel free to add to this resource for people who want to learn more about Intelligent Design. Continue reading Intelligent Design

Discovery Institute: Teach the Controversy

The Discovery Institute continues its terrorist-like tactics in the wake of a very successful airing of an anti-creationism Public Broadcasting System documentary.The DI is providing helpful information for teachers and administrators who want to cost their school districts millions in legal fees and experience deep embarrassment. School administrators: Be afraid. Some of your teachers will read it and you will not be happy at the results. Continue reading Discovery Institute: Teach the Controversy

Religious Scholors to Debate Flying Spaghetti Monster

Hot off the presses:

When some of the world’s leading religious scholars gather in San Diego this weekend, pasta will be on the intellectual menu. They’ll be talking about a satirical pseudo-deity called the Flying Spaghetti Monster, whose growing pop culture fame gets laughs but also raises serious questions about the essence of religion….

Continue reading Religious Scholors to Debate Flying Spaghetti Monster

Sidr: Aftermath unfolding

Do you remember the Christmas Tsunami? I remember well that it was a good example of the public’s demand for knowing the death toll and the press’s demand to feed that need interacting with a crappy network of information flow, to the extent that the early death tolls counts were utterly absurd and the rate of climb of this estimate was astounding.Will this be the case with Sidr? Continue reading Sidr: Aftermath unfolding

Evolution of Birds: New Evidence for Foraging Behavior

Birds evolved during the Mesozoic, during the various “Ages” of the dinosaurs, as a subset of those dinosaurs. Many researchers believe that these early birds were different from their then very close dinosaur cousins because of their flight adaptations, and some have linked this idea to flight-based or tree- based foraging.

Today, most birds fly (counting by species) and their flight is linked to their primary dietary adaptation. Some birds actually feed on the wing, while others fly to food sites and once there do not locomote very much. Other birds forage on the ground habitually. The difference between these two kinds of birds should be evident in the morphology of their feet.

If you examine bird feet today and can successfully characterize these feet in a way that links reliably to mode of foraging, then you should be able to look at Mesozoic bird (and dinosaur) feet and say something about how they foraged. In this way, you can test the hypothesis that early birds were flight- and tree-foragers rather than foot-foragers.

A paper in Current Biology does this.Blogging on Peer-Reviewed Research
The first thing the researchers had to do was to deconstruct commonly held conceptions of bird locomotion and positional behavior. In other words, they noticed that the way we characterize birds … as “ground-dweller” vs “percher” vs “climber” … requires “summarisation of potentially disparate aspects of behaviour and morphology … with emphasis on the ‘ability/inability’ to perch. However, many ‘perchers’ visit the ground and some ‘ground-dwellers’ can perch.”The authors re-categorized the birds into groups that were both finer than those normally used, and based on a better set of observations of bird behavior, focusing not on how birds cling (or fail to cling) to various arboreal surfaces, but rather, how they use their feet to forage.They then measured “claw angle” .. the angle between key physical landmarks on the third toe … which they believe varies in relation to mode of foraging.

These data separated out by category of foraging very nicely:i-0f92c0147baff15faecba3c915caa16f-BirdForagingAndClaw.jpegTo someone who studies the relationship between morphology and behavioral adaptations, this graph is a real wet dream. One wonders if they made up the data. But they didn’t.The top part of this graph shows the claw angle (Y-axis) increasing from left to right across the foraging categories into which the authors placed the birds. Ground foraging birds are on the left, others towards the right.

This is done for two phylogenetically distinct groups of birds and shows the same pattern for both of these large taxa.This is very nice work. In and of itself this morphological pattern is an important contribution. But there is more.The lower right part of the graph shows the claw angle measurements for Mesozoic genera. They appear to be mostly ground foragers. The horizontal line in this graph is the cutoff point that seems to work for living birds (lower than 100 degrees = ground forager, higher = varying degrees of tree foraging). One Mesozoic specimen is above this line, which does not mean much … it could be an outlier.In other words, it is reasonable to conclude that ground foraging was the predominant behavior among the Mesozoic birds.In particular the hypothesis that Mesozoic bird evolution involved flight-and tree based foraging is not supported by this analysis. This forces evolutionary biologists to change their thinking about early bird evolution. Science marches on

 

GLENN, CHRISTOPHER L. BENNETT, MICHAEL B.(2007): Foraging modes of Mesozoic birds and non-avian theropods. Current Biology, 17, R911-R912.