Alaskan Mesozoic 3

One of the problems faced by teachers at any level is questions.

Very young children are full of questions – the problem is keeping a class from disintegrating into chaos. Somehow parents, school and adults in general manage to turn that questioning off, at least in the classroom. In teaching college courses, I found that it was very difficult to get students to ask any questions. And a good teacher relies on student questions, if only to provide feedback on whether he or she has gotten the point across.

I recall a math class at Harvard where the professor was totally stunned by the abysmal results of the first test. Most of us hadn’t had the least idea of what he was talking about, but were so confused we didn’t even know what to ask. If some of us had just spoken up and said “I don’t understand that,” he might have realized what we only understood in retrospect – he had not bothered to find out exactly what the preceding class had covered, and a large and essential chunk of the necessary background to what he was teaching had never been covered. In this case, I think we were all afraid of looking stupid in the eyes of the other students.

I’m not talking about huge lecture classes, of course. But in smaller groups, often with a graduate assistant, questions do need to be asked – and frequently are not. As a result, those who teach in college settings generally plan their lectures assuming there will not be many questions.

Many of our local OLLI classes, for adults over 50, are taught by college professors, often retired. These lecturers plan their courses as if we were college students, with a typical student’s reluctance to ask meaningful questions. It doesn’t work, at least not in Fairbanks. We older students are full of questions, especially when our instructors are active researchers of what they are teaching.

The final lecture of “The Mesozoic of Alaska” was supposed to cover marine reptiles and pterosaurs. Well, the marine reptile – an ichthyosaur discovered on the North Slope – was indeed covered, in the last five minutes of the two-hour class. I had to ask about the pterosaurs after class.

I think that Pat (who is not retired) intended to give a brief overview of what kinds of dinosaur fossils have been found in Alaska, followed by the story of the excavation of the ichthyosaur (which turned out to have co-discovered by Carl Benson, one of my dissertation advisors) and the trace fossils of pterosaurs. He passed around casts of fossils of numerous types of dinosaurs found along the Colville River, told stories of floating the Colville hunting for dinosaur bones in the thawing banks, and showed artists’ conceptions of the living beasts. And he had to field tons of questions.

I won’t go into the classifications of Saurischia and Ornithischia, you can look at Wikipedia if you’re interested. Here in Alaska, we had Edmontosaurus (a duck-bill) chowing down on the vegetation, accompanied (not always on the Colville) by ankylosaurs,  Thescelosaurus, hadrosaurs and Pachyrhinosaurus. They were eaten by large and small two-legged predatory dinosaurs: big-eyed Troodons, the Tryannosaurid Albertosaurus, and another small, pack-hunting killer, Sauromitholestes.

The pterosaurs? They were here, as shown by a trace fossil of the “hand” of one. Their bones are so delicate that it is no surprise fossils have not been found yet in Alaska, but they were here. At least there is no problem with their possible migration, which is still hotly debated for the land-dwelling dinosaurs.

Don’t forget to comment for the drawing — I’m including all relevant posts.

The Alaskan Mesozoic

The OLLI classes are on again, and my favorite teachers are back – this time, with a course on the Alaskan Mesozoic.

What’s that? Well, the Mesozoic is the “Middle period” of multicellular life on earth, lasting roughly from 250 million years ago to 65 million years ago. It is probably better known as the age of dinosaurs, although many of the animals of the time often looked on as dinosaurs – weren’t. And the fossils of many of these animals are indeed found in Alaska – which has led to a new look at dinosaurs.

I missed the first class of the series, on the paleogeography of Alaska, but a good deal of it was put together at the Geophysical Institute, where I used to work. I already knew that the mountain ranges that make up most of Alaska were originally island chains, carried into the state on the moving Pacific and Arctic plates and crushed against it. The north slope was actually at a higher latitude than today during the Mesozoic, and while the world (and Alaska) were a good deal warmer then, the sun was still below the horizon 24 hours a day in midwinter. Plants cannot grow without sunlight, herbivores would have a lean time of it in winter, and carnivores need herbivores to survive. It is difficult to imagine cold-blooded reptiles managing this (there are no crocodiles or snakes in mainland Alaska today) so the discovery of dinosaurs, but not fossil crocodiles, at these high latitudes has forced some reconsideration of their cold-bloodedness.

So what are dinosaurs? That was the Saturday lecture.

First, they are diapsids. That means they have two holes (other than those for eyes, nostrils and ears) in their skulls. In contrast we mammals have one on each side and are called synapsids, and turtles have none and are called anapsids. Don’t think you have one? It’s behind your cheekbone, and your jaw muscle passes through it. Feel above your cheekbone and clench your jaw, and you can feel the muscle. Well, dinosaurs, crocodiles, lizards and birds have two such holes.

In order to be a dinosaur, however, something else is required. Diapsids (think reptiles) started out sprawling. At some point some brought their hind legs under themselves – somewhat earlier than we mammals learned the trick – and began to use their forelegs as grasping hands. The first dinosaur probably looked like a large (but not too large) featherless (we think) bird.

And dinosaurs, as defined by being diapsids with upright rear legs and three-toed grasping forelegs, include birds. Furthermore, discoveries over the last ten to fifteen years have made it clear that many perfectly good, classic dinosaurs had feathers. After all, feathers make excellent insulation, as demonstrated by the down parka I wear.

So far, we’ve learned also that some creatures often lumped with dinosaurs are in fact not dinosaurs. The sail-backs often included with dinosaurs, for instance, are in fact synapsids and are our own distant relatives. Pterosaurs and marine reptiles, though flourishing at the same time as dinosaurs, were not dinosaurs, though they were diapsids.

I know there were marine reptiles in Alaska, but I’ll be fascinated to hear about pterosaurs in our long, dark winters. Did they live here, even in the summer? Did their wings allow them to migrate?

Next week we’ll focus on plants, but the final week is scheduled to cover the marine reptiles and pterosaurs. If you can’t wait, there is some information on a PBS NOVA program.

(P.S. That’s a Pterosaur skull that Pat Druckenmiller is holding.)

Prehistoric Park (DVD)

Dinosaurs weren’t the only prehistoric critters to go extinct. Prehistoric Park introduces quite a wide range of extinct animals, from Carboniferous giant insects to mammoths and sabertooth cats. In some ways it is very similar to Chased by Dinosaurs, which I reviewed last week. Again, Nigel Marvin is the explorer. But this DVD has a wider range of prehistoric animals, and a more connected (if even more inane) plot.

The premise of Prehistoric Park is that a park has been set up to provide a haven for animals that have become extinct. I can swallow the time travel (or at least suspend disbelief.) But bring them back to the safety of the present? Haven’t the writers heard that we are in the midst of the biggest extinction event since the end of the Cretaceous?

For that matter, the “rescued” animals–especially the mammoth–really don’t behave as one would expect them to. A mammoth following its rescuer tamely through the time portal? And a Titanosaur towing a jeep for a reward of pebbles? Come on!

Another assumption that makes no sense in the context of time travel is that only the most endangered animals should be rescued. This makes good sense in the real world, where the most endangered animals have to be saved or go extinct. The only way it could make sense given time travel were if the time travelers could change the past. In that case, they should bring back only those animals with no descendants–e.g., the dinosaurs that would have been killed by the meteor. This is never suggested. The logic appears to have been taken over from present day conservation with no examination of why it is true now. Given time travel, it would make a lot more sense to go back to a time when the species was thriving.

That said, the DVD gives a nice range of times and animals, and the people and familiar machines really put their sizes into perspective. The times and animals include the end of the Cretaceous (Tyrannosaurus Rex, Triceratops, Ornithomimus) the end of the Ice Age (mammoth, Elasmotherium) China 125 million years ago (Microraptor, Titanosaur), South America 100,000 years ago (sabertooth cat, terror bird) Carboniferous swamps (giant dragonfly, Arthropleura, giant scorpion) and 75 million years ago (Deinosuchus and a stowaway Troodon.)

This is a BBC/Discovery DVD, and the quality of the reconstructions is excellent. The episode with the Microraptors should ideally be watched in conjunction with NOVA’s The Four Winged Dinosaur, which really studies how this dinosaur might have used its feathered limbs. And I have to say that in spite of my grumbling, this is a DVD I have watched over and over.

Chased by Dinosaurs (DVD Review)

If you enjoy seeing extinct animals in the flesh, thanks to animatronics and computer animation, you’ll probably enjoy this. The addition of people and artifacts such as an ultralight aircraft, a jeep and a sailboat really puts the dinosaurs and sea monsters (ones that really existed) in scale. They are impressive.

On the negative side, the plot (such as it is) is pretty inane. And the explorer, Nigel Marvin …. Well, all I can say is his writers gave him a death wish.

Any reasonable explorer takes precautions. Even a modern camper in bear country knows not to leave food out if you don’t want a tent broken into. I can only suppose that the writers put excitement above being reasonable. I have to say that I was left feeling that this guy was a grade A idiot.

As a bonus, there is a program about the finding of fossils of Argentinosaurus and Giganotosaurus and the argument on whether carnivorous dinosaurs may have hunted in packs. Personally I found some of the against arguments rather doubtful. Carnivores simply do not move as a group the same way a herd of herbivores do. They split up, attack from different directions, and explore. Consequently, a group of carnivores will not leave the kind of trackways a herd does.

This was a BBC science program and overall is well produced, but I have to admit there are very few natural science programs that I do not find errors in. Overall, though, I probably yelled at the screen less often in this than in many other DVDs.

That said, it’s still worth watching for the dinosaurs.

Again, the DVD is Chased By Dinosaurs.