The Amniotic Egg: Amphibians to Reptiles (October 1-5)

It must be time to really “conquer the land”, as we say too often. 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 on this webpage from the University of Bristol. 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 that recent story on Dickinsonia from the Ediacaran found by your classmate Nate. Biomarkers (you remember those) show that it was an animal. This is not a surprising conclusion, but a cool technique.

The Japanese have landed tiny space rovers on an asteroid, and they’re starting to send back images. Postcards from the beginning of our Solar System.

This will not be news to you, but it is a fairly good accounting: What Darwin didn’t know about evolution. There are some nomenclature errors in this popular article, and poor Wallace should have been in the headline too.

Crystals of the hardy mineral zircon are giving us chemical clues about surface conditions on the earliest Earth. Maybe it wasn’t as bad as we’ve thought. There are even hints of life prior to 3.7 billion years ago.

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