It’s too bad avian faces are so expressionless, because you have to wonder what these two birds were thinking.
Pharyngula
Evolution, development, and random biological ejaculations from a godless liberal
It’s too bad avian faces are so expressionless, because you have to wonder what these two birds were thinking.
There is a treasure trove in China: the well-preserved phosphatized embryos of the Doushantuo formation, a sampling of the developmental events in ancient metazoans between 551 and 635 million years ago. These are splendid specimens that give us a peek at some awesomely fragile organisms, and modern technology helps by giving us new tools, like x-ray computed tomography (CT), scanning electron microscopy (SEM), thin-section petrography, synchrotron X-ray tomographic microscopy (SRXTM), and computer-aided visualization, that allow us to dig into the fine detail inside these delicate specimens and display and manipulate the data. A new paper in Science describes a survey of a large collection of these embryos, probed with these new techniques, and rendered for our viewing pleasure…that is, we’ve got pretty pictures!
What kind of lowlife would threaten a dog?
Physiologists have been studying the activity of shrimp on a treadmill—the movie is charming, especially if you like an excess of whirling limbs.
You can tell it’s not a Bally’s ad by the absence of lycra and proudly outthrust breasts.
Here’s another tetrapodomorph fish to consternate the creationists. These Devonian/Carboniferous animals just keep popping up to fill in the gaps in the evolutionary history of the tetrapod transition to the land—the last one was Tiktaalik.
This lovely beastie is more fish than frog, as you can tell—it was a marine fish, 384-380 million years old, from Australia, and it was beautifully preserved. Gogonasus is not a new species, but the extraction and analysis of a new specimen has caused its position in the evolutionary tree to be reevaluated.
How could I forget the big lady at the Natural History Museum? We also got to meet Archy.
Cute, isn’t she? She was also impressive in person—that’s one big squid.
The Science Pundit has a collection of graphics and movies illustrating echinoderm locomotion. Tube feet are spiffy.
Here’s a prediction for you: the image below is going to appear in a lot of textbooks in the near future.
That’s a technical tour-de-force: it’s a confocal image of a Drosophila embryo, stained with 7 fluorescent probes against different Hox genes. You can clearly see how they are laid out in order from the head end (at the left) to the tail end (which extends to the right, and then jackknifes over the top). Canonically, that order of expression along the body axis corresponds to the order of the genes in a cluster on the DNA, a property called colinearity. I’ve recently described work that shows that, in some organisms, colinearity breaks down. That colinearity seems to be a consequence of a primitive pattern of regulation that coupled the timing of development to the spatial arrangements of the tissues, and many organisms have evolved more sophisticated control of these patterning genes, making the old regulators obsolete…and allowing the clusters to break up without extreme consequences to the animal. A new review in Science by Lemons and McGinnis that surveys Hox gene clusters in different lineages shows that the control of the Hox genes is much, much more complicated than previously thought.
