Our Furry Kin and The Greening of the Earth: Evolution of Mammals and Plants (November 6-10)

We’ll start Monday with a review of your second test results, then begin our discussion of early mammals. On Wednesday we’ll be deep into the woods with the Kingdom Plantae.

Mammals evolved so gradually from the reptiles that it becomes difficult to say when the first mammal appeared. (A familiar story that you’ve heard with the fish, amphibians, dinosaurs, and “birds”.) The Wikipedia page on the evolution of mammals is quite good, and the related page on the cynodonts (a type of therapsid which includes the mammal ancestors) is useful. We will talk in detail about the various innovations which characterize the mammal-like reptiles and the early mammals. (And we won’t use all the terms in these pages, of course.)

Plants have been in this course for awhile as a leafy background to tetrapod evolution, but now it is time to take them seriously. The best place to start a general survey of our very distant green cousins is with Berkeley’s fossil plants page. Their fossil plants range chart may be especially useful, although we won’t be using most of the names given there. The most detailed plant website is the University of California on-line paleobotany lab. The diagrams and hierarchical systems of detail here are impressive. You may want to scan these pages for the beautiful line drawings alone. If you want professional detail of fossil plant systematics and distribution, click the homepage of the International Organisation of Palaeobotany. Berkeley’s “Deep Green” website on plant diversity is also useful.

Here’s a ginkgo webpage for everything you want to know about this beautiful tree common on our campus (although it is hardly the only “link between the lower and higher plants”). What is the tallest plant and where is it? A redwood in California measures an astonishing 379 feet.  Check out the oldest living plant — an impressive 13,000 years of life as a clone. It’s also in California. Finally, a short video clip of stomata in action.

The evolution of angiosperms (flowering plants) is a bit contentious these days. Most paleontologists agree that the first definite angiosperm fossil is Cretaceous, but genetic and molecular studies suggest they evolved sometime in the Jurassic. There are disputes over what the fossil record really shows.

Now that you’ve accumulated quite a bit of life’s history, you might appreciate this deep-time clock. I can’t guarantee that all the dates will be correct, but the order of events is good. The main thing you will gain from this page is an appreciation for the scale of geologic time.

Here is the Fall 2017 second test answers pdf. There were 9 tests in the 90s, 15 tests in the 80s, 5 tests in the 70s, 4 tests in the 60s, and 3 tests in the 50s. Two-thirds of the class thus earned A or B on the test. The high score was 96%, the average 80.8%. On the first test about half of the class earned A or B and the average was 78%, so this is an improvement.

Merycoidodon skull, left side (Oligocene of Nebraska).

Geology in the News –

Here’s a nice octopus-like fossil from the Jurassic. It’s not often invertebrate paleontology makes the BBC news!

It’s not often I cite the Daily Mail here, but this is a good popular account of how volcanoes change climate, and why warmer oceans may increase the effects.

A 200-million-year-old “megacarnivore” new theropod dinosaur found, sort of. We only know its footprints, so Kayentapus is a trace fossil, not the actual dinosaur. Impressive nonetheless.

A new pterosaur was found (in part) in Mongolia. It is Late Cretaceous and had a wingspan of about 10 meters. It may have eaten baby dinosaurs!

This entry was posted in Uncategorized. Bookmark the permalink.