Our Cenozoic Mammalian Cousins (November 19)

We had our introduction to mammals back in the Triassic. They were ratty little critters then, but now that the non-avian dinosaurs are gone our mammals have become very serious and prolific.

So many mammal groups appeared in the early Cenozoic that we cannot cover them all in this course, or even mention many of them. That diversity dilemma is actually part of the story of the extraordinary adaptive radiation of the mammals. Note that the three-part division of mammals we see today (monotremes, marsupials and placentals) began in the Cretaceous. You may also want to refer to the mammal evolution site on Wikipedia, which is very well updated.

Again, the webpages from Berkeley will be highlighted here because they are organized in the most useful ways for us. You will want to look at their short rodents page. Now jump WAY up to the proboscidean (elephants, mammoths, mastodons) page just to delight in the wondrous variety in modern mammals. There are many sites devoted to mammoths, mastodons and other “Ice Age” mammals, including the Pleistocene exhibits at the Russian Paleontological Institute. Carnivores are always interesting, and are in themselves highly diverse. They include wolves, dogs, cats, raccoons, bears, weasels, hyenas, seals, and walruses. A hero to your cat is the ancient sabretooth, highlighted in special exhibits this year at Berkeley and the Illinois State Museum. (Watch an old school animation of a sabretooth from the BBC.) You can now make another mammal diversity leap to our unlikely cousins the cetaceans (whales and dolphins; here’s an Eocene whale found a few years ago in Egypt). The ungulates, or hoofed mammals, are an excellent group to use in a study of evolutionary patterns. The artiodactyls (cloven-hoofed mammals) include the prosaic sheep, goats, camels, pigs, cows, deer, giraffes, and antelopes (and now whales!). Their relatives the perissodactyls (“odd-hoofed” mammals) include rhinos, horses and tapirs today, but they were much more diverse in the past. The evolution of the horse is a classic story, told well at the “Fossil Horses in Cyberspace” site at the Florida Museum of Natural History.

Here is the Fall 2018 Final Exam description. (Test seating: Students with last names starting with A through L in Room 205; M-Z in Room 216.) Even though the final is about a month from now, you’ll want to start studying. Those superquizzes will be your encouragement!

Remember: Review sessions every Friday, 3:30 – 4:30 pm, in Scovel 205.

Mammoth tooth from the Pleistocene of Ohio.

Geology in the News –

There is an interesting argument that the Late Cretaceous asteroid hit just the right spot to cause the global extinctions. The hypothesis is that striking an area rich in petroleum injected massive amounts of soot into the atmosphere that further cooled climate. There will be debates soon over this.

Here is an excellent BBC article on saving coral. Are we willing to make the change to ensure the survival of coral reefs and thus oceanic ecosystems? So far the answer is a grim no.

The search for Oort Clouds around other stars has yielded surprising results, with some evidence suggesting they go back to the early days of the Universe.

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