The Essential Dinosaur Pack Disc 2: DVD Review

This disc, although it has a copyright date of 2008, is a collection of TV programs originally aired between 2003 and 2008. Thus none are really up to date.

“The Mystery Dinosaur,” from 2006, deals with the discovery of  “Jane.” This fossil has been variously identified as a Nanotyrannus and a juvenile Tyrannosaurus Rex. The program is primarily about the argument, which could date it, but as far as I can tell, the argument has never been resolved. Thus the program is still fairly current, though it is more science than entertainment.

“Dinosaurs: Return to Life” deals with the observations that the differences between dinosaurs and birds appear to be due to a relatively small number of mutations. Could birds be “reverse bioengineered” to produce something like dinosaurs? Would we really want to?

The four-program series “Dinosaur Planet” first aired in 2003, and unlike the rest of the programs in this set, it is definitely intended to be entertainment. Each of the four episodes focuses on one or two individual dinosaurs and follows them through a period of their lives. Each episode also covers something that is important or intriguing in the fossil record, and links back to that record. Thus “White Tip’s Journey,” featuring a Velociraptor,  suggests one explanation for the famed (real) fossil of a Velociraptor locked in a death struggle with a Protoceratops.

“Alpha’s Egg,” featuring the large sauropod Saltasaurus and the medium-sized predator Aucasaurus,  is based on the discovery of  a Saltasaurus nesting ground,  fossilized in Patagonia.

Pod of “Pod’s Travels” is based on a Pyroraptor,  a European raptor genus. The episode includes the natural hazards (earthquake, tsunami) that made occasional travel between the islands that made up Europe 80 million years ago possible. The focus of the program is on the dwarfing effect that islands tend to have on species. Pod is a Gulliver among Lilliputians when a tidal wave sweeps him to a much smaller island.

“Little Das’ Hunt” follows a juvenile Daspletosaurus  (an earlier close relative of Tyrannosaurus Rex) learning to hunt, and a herd of Maiasaura. The episode is based on a group of Daspletosaurus and Maiasaura found fossilized together in Montana, but the evidence for the kind of pack behavior shown in the episode is scanty and controversial.

Obviously there is a good deal of imagination going into the behavior, color, feathers or lack of them, musculature and behavior of all of these dinosaurs. Here I want to mention three, because they struck me so strongly.

The first is the underline of the creatures portrayed.  Theropod dinosaurs did indeed have a bone jutting back from the pelvis. However, the velociraptors are shown as having this bone stick out of the body, covered by a narrow wedge of tissue. It seems to me that this arrangement would be very susceptible to breakage, and that evolution would have reduced the length of the bone fairly fast. It makes much more sense that the tail and the posterior part of the belly were much deeper, with the projection buried in muscle. In fact a mummified hadrosaur had exactly this conformation, with a tail much deeper than anyone expected. Why not Velociraptor?

Second is the behavior of prey dinosaurs. Granted they didn’t have much brain, but instinct is also guided by evolution. Threatening a predator with teeth adapted to munching relatively soft leaves, and exposing the vulnerable neck in the process, does not make sense. Kicking (recent work has shown sauropods had vicious kicks) or tail swipes are far more reasonable for the big plant-eaters. This bothered me as far back as the Disney dinosaurs in Fantasia, when the stegosaurus turns to try to threaten T. Rex with its tiny mouth, instead of lashing out with its spiked tail. Now Disney may be forgiven – after all, Fantasia came out in 1940. Between making his dinosaurs animatable by artists drawing each cel by hand and the paleontological knowledge of the day, he did a respectable job even if his sauropods did have necks like snakes and his characters never actually lived at the same time. But that stegosaurus is pure theater, and Discovery Channel should have known better.

The third is grass. There is now some controversy over whether dinosaurs and grass coexisted, but the amount of grass shown is almost certainly incorrect.

Overall evaluation? Watch, but don’t believe everything you see. This DVD has a lot of creative interpretation, some of it almost certainly wrong.

The Essential Dinosaur Pack Disc 1 (DVD Review)

This set of two DVDs, although the cover has a date of 2008, in fact combines episodes originally aired on the Discovery Channel from 2001 to 2008. The first disc contains four episodes:  Valley of the T. Rex (2001), T-Rex: New Science, New Beast (2006), When Dinosaurs Roamed America (2001) and Utah’s Dino Graveyard (2005). Keep the true dates straight, because our interpretation of dinosaurs is changing rapidly, and the episodes at times seem to contradict each other. None of the interpretations are truly currant, or represent today’s ongoing controversies.

This DVD focuses on the processes of finding, unearthing and interpreting fossils, with only minor clips of computer generation of the living animals. It will be of more interest to budding paleontologists than to those looking for entertainment.

Valley of the T-Rex looks at the idea put forward by Jack Horner that T-Rex was primarily a scavenger, not a predator. The idea is hardly new, and is far earlier than the discovery of T-Rex’s tiny arms – Wiley Ley proposed it as a science article in the April 1943 issue of Astounding Science Fiction. I really doubt that there is any such thing as a pure predator or a pure scavenger. Any predator will scavenge a fresh kill, and any scavenger will kill an animal down and helpless, if only by eating it. Like the short-faced bear, T-Rex may have used its impressive size to intimidate other predators off their kills, but that doesn’t mean it never killed.

T-Rex: New Science, New Beast is more balanced, mentioning that how T-Rex fed is controversial but not getting into the controversy. Rather, it summarized new (as of 2006) methods of investigating dinosaur fossils. This included learning how to tell how old fossil dinosaurs were at death (which led to the discovery of the fantastic teenaged growth spurt of T-Rex and the relatively young age (29) of Sue, the largest T-Rex found.) At least one dinosaur was sexed, though the technique only works with pregnant (with eggs) females. Study of locomotion in modern animals has been applied to dinosaur skeletons, suggesting a lower top speed for full-grown T-Rex than was previously estimated. The episode also mentioned the discovery that some fossil bone had collagen, study of T-Rex bite strength, and the discovery of feathered theropods, leading to the possibility that T-Rex juveniles, at least, had downy feathers.

When Dinosaurs Roamed America goes through the history of dinosaurs, using an American location to spotlight each time period. Remember this segment, and the computer animated clips included, is eleven years old in 2012.

The video starts with New York (Permian-Jurassic, first dinosaurs, early opening of the Atlantic.) It then moves on to Exeter Township, PA (Triassic-Jurassic boundary, theropod-sauropod split.) Utah was a savannah 150 million years ago, wandered over by giant sauropods, their predators, and the smaller herbivorous dinosaurs that survived at their side. New Mexico 90 million years ago was a tropical swamp, with an explosion of flowering plants and broadleafed trees. The notorious K-T (Cretaceous-Triassic) boundary and the final extinction of the dinosaurs is investigated in South Dakota. The video is not bad, but dated.

The final program, Utah’s Dino Graveyard, covers a single location with a huge number of dinosaur fossils of a single species. Falcarius Utahensis was a strange beast even by dinosaur standards, as are most of its Therizinosaurian relatives. It is one of the earliest of a group that evolved from raptor-like carnivores to big-bellied but still relatively upright herbivores. This does happen – all dinosaurs, even the huge sauropods such as Apatosaurus evolved from early ancestors that ran on two legs and preyed on insects. More recently, the giant panda seems to be a bear that has embraced a diet of bamboo.

The real question is, what killed large numbers of the same species? Their preservation seems to be due to the fact that they all died near ancient springs, with rock from the spring deposits forming a cap that preserved their bones, but could the spring also have played a role in their deaths?

In general the computer graphics are adequate but not inspired, and at times show behavior I have doubts about — but I’ll save that critique for the second disc.

IMAX T-Rex: DVD Review

Back when IMAX theaters were rare and found mostly in museums I went to a 3-D IMAX show – T-Rex – at the Smithsonian Natural History Museum. Even then I found it a peculiar amalgam of three-dimensional animation, paleontology, and not-very-good science fiction. (OK, it’s pretending to be science fiction, but it’s closer to bad fantasy.)

I got the DVD a while back, when I was getting most of the dinosaur videos available.

It’s a 1998 movie, and of course a lot has been learned about T-Rex in the intervening 14 years. Not enough, however, to make me feel like trying to pet one, or think it was capable of gratitude to another species!

Both the animation and the sequences of paleontologists in the field are fascinating, and so is the information about museum displays and Charles Knight. If the producers had stuck to the informational part, and perhaps used the idea of T-Rex as a nurturing mother in a more reasonable way, this could have been an excellent film, though a short one (44 minutes.) However, they insisted on adding a plot which involved something that left the audience guessing whether dreams, hallucinations, or time travel was involved. The supposed resolution, with a paleontologist finding a 20^th century watch, was totally ridiculous. Complex metal objects like watches simply do not fossilize.

Further, neither the big-screen of IMAX nor the 3-D were available in the DVD I have. This was a movie which depended on these effects.

Interestingly, there is considerable current research on the extent to which tyrannosaurs might have lived and hunted in family groups, and it is generally recognized today that birds are fundamentally modern dinosaurs, descended from the same bipedal group to which T-Rex belonged. The DVD, watched with the production date in mind, does give some interesting information on the history of how we think about dinosaurs. Just forget the plot!

p.s: As an update on last week’s post about ice jam floods, there is still a flood warning out for the Salcha River area, and the ice went out at Nenana at 7:39 yesterday evening. This can happen from April 20 to May 20, so breakup this year was early.

Allosaurus: DVD Review

This is a Walking With Dinosaurs program, and like most of that group the animation is excellent, even though the narration tends to present guesswork as fact. Case in point: the red color above the eyes, mentioned as a sign of sexual maturity. To the best of my knowledge (and it was certainly true in 2000, the copyright date) both color and possible significance are pure speculation.

The story follows the life of an Allosaurus, “Big Al,” as reconstructed by forensic analysis of the bones of one of the most complete Allosaurus fossil skeletons ever discovered. I found the second half of the video, which deals with the actual forensic analysis, even more interesting than the fictionalized video of Al himself.

Al was certainly a “live fast and die young” dinosaur. His bones are remarkable not only for being found relatively complete, but for the number of healed injuries they show. How did he get those injuries? The main program gives possible reasons, though of course things may not have happened exactly as shown. But we know he survived broken bones that had time to heal completely and a toe infection that must have lasted for months before his death.

I would like to make two points about dinosaur DVDs in general. First, our knowledge of dinosaurs is changing so fast that is essential to know the dates at which the videos were made! Dates on the cover of DVDs made up from programs originally broadcast on television can vary widely from dates of the original broadcasts. This one’s from 2000; I’ll go back as I find the actual copyright dates on the individual programs and add them to earlier reviews.

Second, for some reason animators feel compelled to have their dinosaurs roaring (or making other sounds) at every opportunity. Now animals do make sounds, and we certainly expect dinosaurs did. But predators, in particular, make sounds at particular times for particular reasons. They may communicate with sounds. They may warn off rivals, or try to intimidate them. They may call to attract mates. They may make sounds to deliberately panic prey. They try very hard not to make a sound when they are trying to stalk prey! Certainly they do not hiss, growl, or roar while setting up an ambush!

All in all, this DVD is worth watching if you want to watch dinosaurs in action, or see what the state of dinosaur science was in the 20^th century. Just keep in mind when it was made.

Cinderella (DVD Review)

I’m not a big fan of modern records. My taste runs to Mahler, the classics, Andrea Bocelli, Sarah Brightman, and the occasional soundtrack. I can’t say that I ever consciously listened to a record by Whitney Houston. Nevertheless I feel I knew her a little through a DVD I’ve watched many times: Rogers and Hammerstein’s Cinderella, as co-produced by Whitney Houston and Walt Disney Enterprises.

I’ve loved the music since I first heard it, on the original CBS broadcast with Julie Andrews as Cinderella in 1957. I don’t know if there even were color televisions then. We certainly didn’t have one, and my DVD of the original broadcast is in black and white.

The Disney version has a somewhat more traditional ending than the original broadcast, but the music is just as glorious, if not more so. And color? This DVD fairly pops with color, from the fabric swathes during the food dance (I don’t know what else to call it) to the row of gaily-patterned stockings on the feet of the girls waiting to try on the glass slipper.

The cast is multi-ethnic to a somewhat startling degree. Whoopi Goldberg and Victor Garber as the king and queen gave me no problems, nor did Paolo Montalban as the prince. Brandi as Cinderella gave life to some of my favorite songs, and Bernadette Peters was a wonderfully wicked stepmother. But the stepsisters…

There is nothing wrong with the performances of Jenne Cox and Natalie Dusselle. Their interaction, as rivals united only in despising Cinderella, was excellent. But I can’t help looking at things with a geneticist’s eye, and for years I was bothered by the idea that the thin, pale-skinned redhead and the plump chocolate-skinned woman were full sisters, both the daughters of a very pale-skinned mother. Recessives are unlikely to be that well hidden.

Finally, I realized that there is absolutely nothing said about how many times the stepmother had been married! Three times, obviously, with her two daughters having different fathers, and the third marriage being to Cinderella’s father. Now I can relax, my inner geneticist satisfied, and simply enjoy the DVD.

Whitney Houston played the fairy godmother with the aid of some special effects from the Disney team, and she was magnificent in the role. According to the featurette on the DVD, she was a real-life fairy godmother to Brandi, too.

I suppose it’s a bit light and fluffy by the standards of today’s movies, but it’s still one I can watch over and over again. Go Cinderella – and some day I’ll do a comparison of some of the DVDs and retellings of this story.

Oceanography (Great Courses) DVD Review

Oceanography: Exploring Earth’s Final Wilderness

It’s been almost 50 years since I took an oceanography course, so I ordered this course as a refresher. It was a refresher all right, and not just of what I remembered of oceanography — this course covers everything from the history of the Earth to modern-day pollution. As one of my old colleagues at the Geophysical Institute says, “It’s not Planet Earth, it’s planet Cloud-Ocean.”  And this course was a marvelous refresher of the whole of geophysics, core to tropopause, and some biology with the whole thing straightforward enough to be understandable to almost anyone.

It started out conventionally enough, with an overview of the history of oceanic exploration. But many of the observations of the ocean basins demanded explanation. Why did the mid-Atlantic ridge exist, for instance? The Challenger Deep? For that matter, why were island arcs so often paralleled by trenches and home to volcanoes and earthquakes? What were the magnetic stripes discovered during World War II? How was it that the sea floor, which should have been receiving sediments from the continents throughout geologic history, had astonishingly young bedrock when drills began to penetrate those sediments? Some of these questions were touched on 50 years ago, some were hastily swept under the rug, and some (such as the puzzlingly young age of the seafloor bedrock) had not even been discovered yet.

These questions eventually led to the theory of plate tectonics, and several lectures on these DVDs are devoted to explaining this theory and how it came about. But that’s a small part of the first two discs in this set of six.

The physics and chemistry of water take up several lectures. Waves, rogue waves, tsunamis, and tides are covered, along with some of the physics of water. For something so familiar (oxygen and hydrogen are two of the most common reactive elements in the universe) water has some astonishing properties. Not only does it have an extraordinarily high heat capacity and is it very nearly the universal solvent, it is one of the few compounds in which the solid phase is less dense than the liquid. In other words, ice floats! We’re so used to this we don’t even think about it, but the world would be very different if ice sank, as most solids do in their own melts.

Life in the seas is interesting in itself and also critical to feeding our global population. Food webs, plankton, jellyfish, fish, marine mammals and birds and whales all get their moments of exposure, along with fish farming.

Then the course moves on to coasts: estuaries, deltas, beaches and sea cliffs. Life is here, too, from sea grasses and mangroves to coral reefs.

The lectures then cover storms, the deep ocean circulation, and the effects of climate change and pollution.

As a meteorologist I would of course like to have seen more on the role of the oceans in influencing weather. Not only are the oceans the great flywheel of climate, and their slow response one of the problems in climate modeling, they provide much of the water vapor that transports energy around the globe. Still, 36 half hour lectures can’t cover everything. Professor Tobin certainly tried, though, and for a single course succeeded brilliantly.

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!

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.

Skywatching: DVD Course Review

Every now and then I order a course on DVDs from The Great Courses. Most recently, I’ve been viewing Skywatching, a course by Alex Fippenkio on the sky, day and night: what can be seen in it and the physics of why it looks the way it does.

Roughly the first third of the course deals with what we can see in the daytime sky. Dr. Filippenko discusses sky color in midday and when the sun is rising or setting, clouds, lightning, and the interaction of sunlight with water and ice (giving rainbows and halos.) This is closely related to what I researched and taught, so I didn’t really lean anything new. The presentation, however, was generally good. I did catch an error in one diagram, but I suspect that was the graphic designer. (The diagram is the one used to explain polarization in reflected light, and the error is that the angle of reflection and the angle of incidence are not shown as equal.) I was also rather disappointed that Dr Filippenko did not point out that frozen droplets are initially near-spherical, and develop their hexagonal prism shape (and the optical effects this produces) only later, by vapor-phase growth. But I suppose I shouldn’t expect everyone to be familiar with ice fog.

This section of the course should be of particular interest to writers needing information on sky and cloud cover, storms, and less common phenomena such as rainbows or sundogs. If you are going to describe an evening sky, you’d better have some idea of what’s happening.

Roughly half the course deals with the constellations and observing the bodies of the solar system. Most of this I was familiar with as an amateur, and I’ve used some of it — lunar phases and seasons, for instance — in my writing. Every writer who wants to put a moon in the sky should watch the section on lunar phases. Rising crescent moon in the evening? Nope. Just doesn’t happen. Neither does a narrow crescent high in the sky.

The lecture on solar eclipses brought back the one I saw, shortly after I moved to Alaska in 1963. I didn’t have a car yet, but two other graduate students gave me a ride down to Sourdough, Alaska to see the total solar eclipse of July 20, 1963. There were scattered high clouds, and while they added suspense –would the sky be clear during totality? – they wound up adding to the experience. Every bright spot of Bailey’s Beads had its own rainbow (technically iridescence.) I know I took a picture; I remember taking photos both before and after the eclipse, the ones after being a series with the exposure set at a constant value to capture the change in the light. I found that series, but so far the ones before and during totality are missing. They may have been separate from the others and lost during the fire twelve years ago.

Overall I’d give the course an A. Dr. Filippenko is a wonderful teacher, and with few exceptions the graphics are excellent. The course takes 3 DVDs and consists of 12 45-minute lectures.

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.