Bizarre Dinosaurs DVD Review #IAN1

All dinosaurs are bizarre, by mammalian standards. Some, however, are bizarre even to paleontologists, and the title program of this DVD is devoted to them. There is, however, a secondary program, not even mentioned on the cover, which to me was of considerably more interest.

Most of these animals are considered bizarre because they have appendages, preserved in the fossil record, that leave paleontologists wondering just why these animals have that appendage. Take the 33 foot-long Anargasaurus, for instance. Why on earth did this plant-eater have a double row of bony spines down its back? Reconstructions tend to show it with skin forming a double crest supported by those spines, but why? The only answer anyone had come up with is some kind of display crest, like the peacock’s tail.

Display organs are common, especially in today’s birds (which after all are modern dinosaurs) so I suppose it’s as good an explanation as any for such things as the plates of a Stegosaurus (which would have been potato chips to a large carnivore) or for the fanciful neck frills, often richly supplied with blood, of the Ceratopsids. Were horns used to fend off predators, of for fighting off rivals within the species? Or just for display?

In some cases the peculiarities might be associated with feeding. Take the Epidendrosaurus, for instance, a sparrow-sized dinosaur with an incredibly long third finger. Did it use its long finger as the aye-aye in Madagascar today does, to find insects in the bark of trees? Then there’s Nigersaurus, with a broad, flat head with a very wide muzzle resembling a vacuum-cleaner nozzle. Did it stand in one place and hoover up the vegetation?

This DVD is less interesting than most of the National Geographic programs scientifically, but it does show some interesting dinosaurs. If you want information on some of the animals shown, National Geographic has both an interactive site and a magazine article by John Updike.

The secondary program, which was a total surprise, should have been part of the Prehistoric Predators DVD I reviewed earlier. It was concerned with a much more recent animal, one I’d met before in Prehistoric Park—a predatory, flightless bird that could almost hold its own with sabertoothed cats and dire wolves. Certainly it seems to have taken down the same kind of prey.

These terror birds were not what you want to attract to your backyard bird feeder! Imagine an oversized ostrich with the hooked beak of a raptor, that beak (and head) enlarged to the size of a rather large war axe. With ostrich speed and taller than a man, they evolved to be the top predators on the South American continent, for many millions of years an island continent. Then a few million years ago, the isthmus of Panama joined it to North America, ending the isolation in which the terror birds had evolved. Animals crossed the new isthmus both ways. Opossums, armadillos, and porcupines moved north, but a far greater number of placental mammals moved south.

Surprisingly, a few terror birds did move north, as their fossils have been found in Florida. Did they meet with the earliest humans to colonize North America? Or were they simply unable to compete with the mega-predators already here? They did seem to survive for a long time in North America, but the jury is still out on just how long they lasted.

Tomorrow’s the day to look at quotes from Lewis Carroll, but I’ll also have a guest appearance on another blog, Christine’s Words. Stop by!

Jarn’s Journal Day 718

This is part of the (fictional) Journal of a human-like alien stranded on Earth, in southern Africa, 125,000 years ago.

Day 718

I have to get hold of myself and do something! I’ve done nothing but mope the last fiveday—I haven’t even kept up this journal, or marked where sunset occurs. The fact is, I’ve gotten so used to company that I’ve forgotten how to function without it.

How did I survive before I found Songbird? Mostly, as I recall, I was trying to stay alive and to explore this place where I found myself. Staying alive is not much of a problem now – at least I know what is edible, and if I can’t find it nearby, I can teleport to a number of places where food can generally be found. Exploring ….

I need shoes! Between Songbird and her people I have a reasonable wardrobe – not the kind I am accustomed to, but quite enough to protect me in this relatively warm environment. I have containers. I know now how to cook after a fashion. I have shelter. I cannot teleport to a place where I have never been, and I cannot walk very far to find places I have not yet seen – which is most of the landmass on which I find myself.

Can I make something to protect my feet?

The buffalo hide is tough enough for soles, but I need something to fasten it to the bottoms of my feet without chafing. Straps of the softer hides, perhaps?

I have teleported to really distinctive landmarks, and from them to other landmarks. That is how I found the jungle with its fruit trees, even before I found Songbird. But my ship shoes then were considerably more usable than they are now. It still comes back to footwear.

So the first “something” I have to do is to start leaning to make some kind of shoes or sandals. The second? Work out a better local calendar, so I know when to start looking for Songbird’s people to return.

Book Reviews

Occasionally I review books, including my own. Here is an index to posts that can be considered in some sense book reviews.

Book Reviews

Homecoming 10/20/10
The Book Video is Here! 12/15/10
Quick Comment on Reading 2/8/11
Homecoming Award 3/1/11
Beauty and the Beast 3/24/11
The Animal Connection 6/28/11
Tourist Trap: What’s it About? 8/16/11
Shipbuilder (Guest Post) 9/8/11
Is That a Ghost? 10/31/11
Once and Future Giants 11/22/11
The Land of Painted Caves 2/28/12
Tourist Trap 3/27/12
Pride and Prejudice 4/17/12
The Fire Rose 8/14/12
Anne McCaffrey’s Pern novels 8/28/12
Rescue Operation Preview 9/4/12
Alone in Paradise (blog tour) 9/6/12
Darcy’s Decision 1/22/13
The Real Jane Austin 3/12/13
Georgiana Darcy’s Diary 4/9/13
Darcy’s Diary 5/7/13
Fitzwilliam Darcy, Gentleman 7/10/13
Death Comes to Pemberley 8/13/13
Mr. Darcy’s Guide to Courtship 9/10/13
Jane Austen, Game Theorist 10/8/13
Betrothed to Mr. Darcy 11/12/13
Pride and Pyramids 12/10/14
Mansfield Park 1/14/14
The Matters at Mansfield 3/11/14
Mansfield Park and Mummies 5/13/14
Mansfield Ranch 7/8/14
Mansfield Park Revisited 8/12/14
Murder at Mansfield Park 9/9/14

Sky Monsters (DVD Review)

No, they weren’t dinosaurs. True, model sets of extinct animals often include saber-tooth cats, sail-backs (which were mammal-like reptiles and more closely related to us than to dinosaurs) and extinct marine reptiles as well as pterosaurs, but none of these are actually dinosaurs. Pterosaurs did, however, live alongside dinosaurs and are of great interest as the largest animals ever to fly on their own.

This DVD, another of the National Geographic series, looks at the mystery of pterosaur flight. As usual, the animation is not very exciting, but the scientific work and the attempt to build a mechanical pterosaur more than makes up for that.

The big questions are, how large did pterosaurs grow and how did they fly?

One of the threads of the program is the rather controversial discoveries of trackways and fossils suggesting even larger pterosaurs than Quetzalcoatlus, which itself had a wingspan of 10 meters (33 feet.) That’s three times larger than an albatross, the largest flying bird alive today. Forget the giants; how did even the ones we’re reasonably sure of fly?

The meat of the DVD, as far as I was concerned, was an attempt to build a robotic pterosaur, controlled like a model airplane. The result was not wholly successful, but a great deal was demonstrated about pterosaurs in the process.

First, pterosaur wings were a good deal more complicated than the sailcloth that was first tried. They had oriented stiffening fibers, muscles within the wing membrane, a good blood supply to the wings, a furry covering that (like the dimples on a golf ball) helped aerodynamically, and some kind of built-in sunscreen. (Bats are nocturnal in part because their wings would sunburn too badly in daylight.)

Control was incredibly sophisticated, certainly more so than could be mimicked by a model airplane controller. Much of the maneuvering of a real pterosaur was probably as automatic as keeping your balance is to you – possibly more so, if the speculation that baby pterosaurs were born knowing how to fly is correct. Changing the shape of the wings and the tilt of the head would have been automatic for a real pterosaur. Not so for the model, and it is hardly surprising that it was not fully successful, even aside from the problems of finding components and power sources of sufficiently light weight. Pterosaurs, like birds, had very light bone structures.

As entertainment this DVD falls short. But as documentation of a fascinating experiment, it is worth watching.

Prehistoric Predators (DVD Review)

No, they’re not dinosaurs. These critters are much more recent than the 60 million years since dinosaurs walked the Earth. In fact, our own species may be in part responsible for their demise. They were the top predators of Ice Age North America, and while the cause of their extinction is still subject to debate, they died out, along with their prey, shortly after humans first migrated into the Americas.

The DVD has National Geographic programs on three animals: the saber-toothed cat, the dire wolf, and the short-faced bear. Fossils of all three are found in the La Brea tar pits, and the excavations at La Brea are repeatedly discussed on the DVD. It is subject to the usual bias of this series: good interviews with scientists; poor quality animation clips which are repeated over and over. Another problem is that the science is posed on a “proof” basis when in fact science works by disproof. In general the narrator speaks of “proof” when the scientist involved has shown that his or her hypothesis as not been disproved. This is a very common problem with National Geographic science DVDs.

All three animals hunted the same mega-herbivores: bison, horse, and mammoth. In the same habitat they selected somewhat different prey. Camel and (for the short-faced bear) ground sloth may also have been on the menu, but all three predators were specialized to go after very large prey.

The saber-toothed cat was no more a tiger than it was a house cat. Its weight was in the same range as the modern lion, but it was far stockier and more muscular, with a short tail which reduced its agility at a run. It probably was much more of a wrestler than the modern large cats, and a fair part of the program is devoted to the question of how it used its saber-like but brittle canines for killing. It’s not as obvious as it seems; those oversized canines would have slid off the rounded belly of a prey animal. Nor was its skull constructed for a hard bite. But I have a feeling that it may have used its momentum more than the video clips suggest in pulling down a large animal. (I suspect also that any mammoths it killed were young, very old, or injured. I have a highly unsuccessful saber-tooth attack on a mammoth calf with its mother close by in Tourist Trap.)

The dire wolf closely resembled the modern gray wolf, but was considerably larger and sturdier, with greater bite strength. It probably ran in larger packs than modern wolves, but is thought to have had a very similar hunting style. I suspect the video clips show a far more immediate pulldown of prey than actually occurred. With very large herbivores thick on the ground, the dire wolf would have been an advantage over the gray wolf. When only smaller game became available, the faster, lighter, more behaviorally flexible gray wolf survived and the dire wolf did not.

The third of the predators, the short-faced bear, may not have been a predator so much as a scavenger, stealing kills from the other large predators. It was a very large bear, larger than the largest of the modern grizzlies, such as Kodiak bears. Its legs, however, were relatively long and slender, and it seems to have built for efficiency of gait rather than speed. It probably had an exceptional sense of smell (modern grizzlies have a better sense of smell than bloodhounds) so it was actually well adapted for stealing the kills of other predators. Certainly grizzlies today steal wolf kills if an opportunity occurs. But as I said, possibility or even probability is not scientific proof.

As an introduction to these three Pleistocene predators, this DVD is definitely worth watching. But don’t take everything it says too literally.

Jarn’s Journal Day 625

This is an entry from the (fictional) Journal of Jarn, an alien stranded on Earth some 125,000 years ago, during the interglacial preceding the one we are in. His stranding ultimately led to the Jarnian Confederation, the setting for my science fiction novels Homecoming and Tourist Trap. The setting is Africa, in the southern hemisphere. The Journal to date is also posted on my author website.

Day 625

I think I am beginning to have some handle on the seasons of this planet, and how they affect the nomads. The rains come a little before the southern solstice. It takes a few days for the flush of new growth, which is followed by the herd animals and the nomads and other predators who hunt them. Not that there aren’t some predators, and animals they prey on, year round, but the migratory herds are far more numerous.

I teleported to the nomads’ camp today. The shaman asked me about the fish trap Songbird had made after seeing a picture on my computer, and after I answered I asked the shaman why the nomads did not stay in one place as some of the lions and wild dogs do.

“We follow the food,” she said, and I was reminded of my own early struggles to find things I could eat. I could teleport to where food was abundant, once I found where that was. These people could not. But the shaman continued. “Also, we go to meet with other clans. The young people find mates at the Gather, and it is a good place to trade ideas. But if we stayed there, as you stay at your shelter, there would not be enough food.”

I was reminded of what Songbird had said, when I first asked her why her parents had left her, and the questions I had then about the role of the shamans. “If mates come from different clans, what determines which clan they stay with?”

“That depends on what they want, on the sizes of the two clans, and on the food supply. Sometimes there is a question, and then the shamans of the two tribes decide together. If a clan is too large there is a problem finding food; if it is too small it cannot fight off predators. Our clan could be a little larger, especially with the fish traps you have shown us. That is an idea we will share.

All I had done was observe that the trap in the picture worked because fish could not swim backwards. Songbird worked out how to make the trap and set it where it looked like the natural vegetation of the stream. “Give Songbird the credit,” I urged.

She giggled. “You make us think, and from that comes new things.”

Do not interfere. How can I stop interfering?

Dinosaurs Unearthed: DVD Review

This is the first of a number of reviews of National Geographic’s DVDs on prehistoric animals, so I will start out by saying something that applies to all. They are very good in interviews with actual paleontologists. The computer graphics of the extinct animals are of moderate quality, and there are only a few clips repeated over and over again. These videos are excellent for budding paleontologists or those actually interested in the science of how we know about extinct animals, and are better than series like “Walking With Dinosaurs” in that they allow scientific arguments to be heard. They are not in the same league when it comes to the re-creation of the extinct animals.

This DVD contains two programs originally shown on the National Geographic channel: Dino Autopsy and Dino Death Trap. The first is about a rare fossilized mummy of a hadrosaur, nicknamed “Dakota,” found in the badlands of North Dakota. The fossil was found in 1999 by a teenaged paleontologist, and has supplied information on skin texture and musculature of hadrosaurs. The science is fascinating. The quality of the animation is somewhat less so.

The second program involves the excavation of a site in China. This site produced a number of near-complete skeletons from a period, the Late Jurassic, very poorly represented until now. Most of the attention is given to Guanlong, a very early form of tyrannosaurid. The skeletons are in three dimensions rather than flattened, which has been interpreted as evidence that they were trapped in soft sediments, and lie above each other in a vertical column.

There is speculation about how they died included in the video. Was a volcanic eruption to blame? Was the mud in which they were trapped due to volcanic ash falling into a marsh? Also, while these animals are the early forms of species known from the Cretaceous, the Cretaceous forms were giants, and these animals are relatively small. Guanlong’s back would about reach the waist on a standing human, yet it is an early relative of Tyrannosaurus Rex. What caused the increase in size? Did guanlong really have feathers as part of its crest? They are in the computer animation, and a relative, Dilong, is known to have had primitive feathers. The crest does appear to be a display organ (relatively thin and brittle) and feathers would have made it more conspicuous.

Overall the DVD is worth watching if you are really interested in dinosaurs. If you are looking primarily for entertainment, others are better.

Why an Index?

With 550 posts as of today, I’ve started to have problems remembering what I’ve already put on here. This is particularly a problem with posting existing content such as poems, short pieces from the Summer Arts Festival, or science explanations originally written for the Alaska Science Forum. I can’t remember which books or DVDs I’ve posted reviews on. It also is starting to be a problem when I want to link to a previous post and can’t remember when it was put up or what the title was. And there are posts on this blog that have permanent information, like the series on planet building and the one on horse color genetics, or the book and DVD reviews. I want to make it easier for my readers as well as myself to find things.

I made a start some time ago by adding an index page, which can be accessed from the menu at the top of any page. Right now, the only links are to index pages on my author site. This takes you out of the site and sometimes back in, which is rather clumsy. The index list is also incomplete.

I’m going to start posting an occasional entry which is strictly an index of past posts on a particular topic. These posts will be linked from the index page, and will link forward to the individual blog posts. As it takes a while to find all the posts that belong together, this will be a slow process—probably extending over the next few months. The first in this series, on DVD reviews, is already queued for January 3. Others will follow, most on Thursdays.

I probably won’t be indexing every post. Some, like those early posts which were simply glossary entries for my books, are on the author site and really belong there. Others, like the regular Monday updates on North Pole weather starting in November 2010, can be found easily enough just by using the calendar on the site. But I hope that by the time I have finished this, older posts of interest will be easier to find.

Quotes from “Once and Future Giants”

All of the last week’s quotes are from the same non-fiction book, Once and Future Giants by Sharon Levy. Rather than my usual “who said it under what circumstances” I’m just going to give extended quotes this week, with the part tweeted in italics.

“Conventional wisdom long held that the megafauna fell victim to a warming climate at the end of the last glacial peak of the Ice Age. According to this theory, rising temperatures led to changes in vegetation, altering habitat in ways that proved fatal to many large herbivores and in turn to the dire wolves, American lions, and saber-toothed cats that had preyed on them. Today many scientists believe ancient people were responsible for the extinctions, an idea raised with dramatic flair by paleoecologist Paul Martin.

“From the beginning, people have seen what they wanted to see in the bones of America’s extinct monsters. The devout seventeenth-century colonists who found the first pair of mastodon molars were convinced that they had discovered the remains of a human giant, proof that the David and Goliath story was true.”

“Healthy populations of giant herbivores shape the landscapes that sustain them. But the mastodon at the close of the Pleistocene was so rare it was environmentally insignificant.”

“Seeds that drop to earth beneath the parent’s canopy are doomed: easy targets for predators such as rodents and insects that swarm around fruiting trees. The few that survive to sprout will be shaded to death by the tree that produced them.”

“The clash between elephants and people is as old as our species. To hold on in the long run, elephants need that precious commodity, land.

“Cats, large or small, are the ultimate carnivores: they have lost most of their cheek teeth, except for two or three carnassials that slice against each other, ripping meat away from tendon and bone. A cat’s mouth was made to eat meat and little else.”

“Whoever back at headquarters had come up with the color-coding scheme should try to live with it.” Sue Ann Bowling, Tourist Trap. Penny’s thoughts. The color coding was applied both to the clothing of clients and to the collars, harnesses, and dogsleds – but the two sets of coding caused some major color clashes.

Once and Future Giants: Book Review

I bought Once and Future Giants by Sharon Levy after seeing a review on a science blog. It is indeed an excellent book, though at times it seems that it covers almost too many topics. All, however, have one thread in common: our present ecosystems were to some extent broken by the extinction of large mammals, which can have a profound impact on their environments. Who expected, for instance, that the re-introduction of wolves to Yellowstone would have a positive impact on songbirds and possibly, if the wolves spread far enough, on antelope?

The book attracted me primarily because of the debate on whether the Pleistocene megafauna (mammoth, mastodon, saber-tooth cats, dire wolves, and ground sloths, among others) died out because of climate change or because of overkill by humans, as proposed by Paul Martin. I have Martin’s book, and have been more than half convinced by his arguments. Certainly it has seemed unlikely to me that the warming at the end of the Pleistocene was enough in itself to trigger the extinction of a large number of animals who had survived similar transitions from glacial to interglacial repeatedly in the past. In fact, if we ignore the last fifty years, all the evidence is that it was warmer than the Recent during at least some past interglacials. But Martin very definitely writes as an advocate for his theory, glossing over the problems.

Sharon Levy has written a more balanced book, and one that tends to agree more with my own conclusions. Yes, the changes in climate at the close of the last ice age undoubtedly stressed the Pleistocene megafauna. But the major difference between the last warming and the ones that had happened before was that human beings had emerged as a major predator, and one against whom the large herbivores had no natural defenses. As she points out, the Clovis people need not have killed many mammoths or ground sloths. But human predation, unlike predation by most animals, tends to target healthy animals, often pregnant females. This disrupts the natural social groupings of herbivores, already under stress from climate and habitat change. As the herbivores are killed off, the large carnivores may well die off from starvation. Some of the environmental effects brought about by humans, such as those caused by fire, may also be partly to blame.

The idea of re-wilding, of introducing either the original species (as wolves were reintroduced to Yellowstone) or a surrogate is even more controversial – but the controversies are even more political than the reintroduction of the wolf. Predators are an important part of ecosystems – but people simply do not want to live with animals capable of killing large prey. Neither do they want large herbivores, such as camels or elephants, to compete with domesticated animals for food. The mustang problem is an example of both.

A less well-known problem is certain aspects of the protection of endangered species. In some cases animals or plants stressed by the ongoing changes in climate need to be relocated closer to the poles or to higher elevations – but this is often prohibited by the very laws meant to protect them.

I’m fond of the large megafauna, and would love to see a mammoth in person. In fact the terraformed landscape of Falaron in my own novel Tourist Trap, based on ice-age North America, reflects that wishful thinking. But I have to confess I’d have my doubts about living with the creatures of the Ice Age, or with introduced African lions.