The Amniotic Egg: Amphibians to Reptiles (February 25 – March 1)

I’m ignoring the fact that we’re still a day behind, alas. Please review the links for last week so you’re up to speed on the amphibians. Their descendants the reptiles are an enormously successful class, and their diversity is reflected in the websites devoted to them. I can only give you links to a few of the many groups we will discuss in class this week. (Just wait until we get to the dinosaurs!) You will want to study the wonders of the amniotic egg. Here’s an introductory page to the turtles, and then another for the diapsids. Everything you want to know about the therapsids (“mammal-like reptiles”) can be found here. The best general reptile page I’ve found is from Heidelberg, Germany. It has many  informative (and richly illustrated) pages in English. I’m sure you’ll also like this mosasaur page from the South Dakota School of Mines and Technology Museum of Geology. (I learned a cool mosasaur story during a visit to The Netherlands.) The Wikipedia pages on plesiosaurs and ichthyosaurs are well done. (If they weren’t, we would fix them!) I enjoy this elaborate Oceans of Kansas site, which concentrates on the Late Cretaceous reptiles of the Western Interior.

An amphibious ancestor to the ichthyosaurs was recently discovered in the Triassic of China. This is big news because prior to this the origin of these elegant marine reptiles was a mystery.

A pivotal event in Mesozoic reptile evolution was the Triassic mass extinction, which is well covered (yet again) by Wikipedia. The rise of the dinosaurs starts soon after.

Here  is our Classification of the Phylum Chordata used in this course. It is a list edited just for you. Yes, you do need to know all these names. This is the fish evolution diagram we’ve been using in class.

Mosasaur front paddle (Cretaceous); Natural History Museum of Maastricht, The Netherlands.

Geology in the News –

Here is a recent story on Dickinsonia from the Ediacaran. Biomarkers (you remember those) show that it was an animal. This is not a surprising conclusion, but a cool technique.

A newly discovered sauropod dinosaur in Argentina has extended neural spines, headlined as having a “bony Mohawk”. These spines were not weapons and may have had sexual selection value.

Melting glaciers in Greenland (bad news) are forming new deposits of sand (good news). I had no idea plain old quartz sand had such economic value. There are even sand-based mafia!

A gorgeous multi-layered, multi-spectral view of the Whirlpool Galaxy, courtesy of the venerable Hubble Space Telescope.

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