Lots of tidbits, lots of links, enough to make a few tidbytes, even (8 tidbits = 1 tidbyte).
Feathers may have been an early adaptation, perhaps even basal, of Saurischian dinosaurs (which includes therapod dinosaurs), appearing so early in the evolutionary tree that many therapod dinosaurs (if not most) may have had feathers. Saurischian dinosaurs are one of the two major orders of dinosaurs, the other being Ornithischia, both named for the structure of their pelvic bones. Saurischian dinos have a lizard like hipbone, while Ornithischia has a bird like hipbone. Interestingly, it is the Saurischian group that is thought to have given rise to birds.
What kind of feathers, though? There are eight feather types that are documented within modern and extinct birds, all the way back to feathered dinosaurs.
Xu, X. and Guo, Y. (2009). The origin and early evolution of feathers: insights from recent paleontological and neontological data. Vertebrata PalAsiatica 47 (4): 311-329. – Hosted at wikipedia
Quoting wikipedia’s article on Feathers > Evolutionary stages
Feather evolution was broken down into the following stages by Xu and Guo in 2009:
- Single filament
- Multiple filaments joined at their base
- Multiple filaments joined at their base to a central filament
- Multiple filaments along the length of a central filament
- Multiple filaments arising from the edge of a membranous structure
- Pennaceous feather with vane of barbs and barbules and central rachis
- Pennaceous feather with an asymmetrical rachis
- Undifferentiated vane with central rachis
However, Foth (2011) showed that some of these purported stages (stages 2 and 5 in particular) are likely simply artifacts of preservation caused by the way fossil feathers are crushed and the feather remains or imprints are preserved. Foth re-interpreted stage 2 feathers as crushed or misidentified feathers of at least stage 3, and stage 5 feathers as crushed stage 6 feathers.
Modern birds have feather types 4, 6, 7 and 8 (chicks have filament feathers similar to type 1). The dinosaur that is the subject of the research paper that sciencenews is presenting a press release on a 150 million year old fossil of Sciurumimus albersdoerferi, which has type 1 feathers. A dino covered with type 1 feathers would have looked kind of fuzzy, like a kiwi. Not the fruit, the bird. This supports other evidence for feathered dinosaurs in the therapod group existing as far back as 160 million years ago. Therapods are the dinosaurs come to mind when you think of Tyranosaurs or Velociraptors.
What I am most interested in is that feathers are made of a protein called keratin. Keratin is the waterproof filamentous protein that makes up the outer layer of your skin, hair and nails. Keratin is also present, in one form or another, in all vertebrates. Hooves, horns (like those of a rhino) and baleen are all also made of keratin. Amphibians produce keratin, but only on their feet and perhaps belly, as protection against abrasion, while lizards, snakes and all other reptiles produce keratin all over their skin, and it is one of the major evolutionary adaptations that let reptiles live away from water. Carl Zimmer, one of my personal science journalism heroes, has an article at NatGeo on the evolution of feathers, as well as the evolution of our understanding of the evolution of feathers. I highly recommend reading it and passing it along to interested students of all levels.
Depending on how and where they are expressed, they can make up very different structures, which is one of the primary concepts within evolution. Inventing the wheel is quite easy when the parts you need are already present and only need a modification here and an alteration there. With minor mutations here and expression changes there, scales become modified into feathers, which become altered into more complex feathers with further mutations, each becoming useful for different purposes. And all of this from one group of proteins with incredible versatility.
getting ready to tell couldn’t take the excitement and told us something about the Higgs boson. Great fun for physicists. I have no clue what it means. Dammit, I’m a doctor (biologist), not a doctor (particle physicist)! Luckily, there are people that can explain it.
BoingBoing has a great article up as a piece on cell division and embryogenesis in sea urchins. The videos there would make for great media pieces in the multimodal classroom.
You can learn a lot from fossils, even fossil poop. Yeah, sometimes, feces fossilize (and are called coprolites), and we can learn about the diet of the animal that produced it. In this case, the New Zealand Moa’s coprolites have been examined, and these exceptionally large flightless birds ate plants, and don’t seem to have been too picky. This can relate to the classroom quite easily in any lab where students examine owl pellets. This is a very similar experiment in some ways, examining the contents, but without the carbon dating and DNA analysis.
What drove the moa to extinction around 1500 CE? Humans arrived on the island before this point, and apparently moa were delicious. If only they had survived, I could have a 12 piece New Zealand Fried Moa bucket.
Eugenie Scott of the NCSE talking at the Global Atheist Convention 2012, via Token Skeptic. This talk has some great pearls of knowledge for regarding creationist attempts to do science, and how they don’t mesh with the evidence. (evidence they conveniently ignore)
I love parasites. They are seriously cool. For every animal that feeds itself, there is an animal that lives off of it as a parasite. Some of those parasites have parasites of their own.
The smallest of ants were thought to be safe from phorid flies, a parasite that lays eggs in the heads of ants. The larva emerges, eats the goodies in the ant’s head, and when it is ready to emerge as an adult fly, the head falls off and the fly comes out.
Well, size doesn’t matter to a newly described species of fly that is smaller (0.4 mm long) than any previously described member of the family. So far, the researchers have no idea what the host of this tiny parasite is, but you can be sure they are looking.
In any discussion of how organisms gain their food, parasitism comes up, and visceral examples like this fly can be very interesting to students.
Edited to add this video
Coffee. Need I say more? OK, history and pharmacology of coffee.
Via Jerry Coyne, wild macro photography of some very cool caterpillars, some of which should be hands off. BTW, the description on the page goes with the insect on the next page.
I would never work with chimpanzees. Even before you get to the ethical issues, they scare the E. coli out of me.
Ants that farm and raise aphids for honeydew and for food have altered the evolution of their livestock.
Mass extinctions can have subtle effects on evolution.
Want to have some fun in an ecology class? Give your students a paper on modeling bigfoot reports!
Interested in a challenging discussion on how to change behavior in a third world setting? Give the class this.
Via BoingBoing, reasons to hate standardized tests. My number one pick from this WaPo piece, ” because they measure only “low level” thinking processes.” Bloom’s Taxonomy? Anybody? Hello?