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Documentary, PaleoWorld PaeoWord S01E09 - Dino Sex
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AnimalsTranscript
00:03On those hot Jurassic nights, how did the dinosaurs make the Earth move?
00:09For millions of years, their sex lives have remained a primordial puzzle.
00:15Now science is giving us a tantalizing look at how these creatures courted, mated, and cared for their young.
00:26It's time we had a frank talk about dinosaur sex.
01:03For 65 million years, the love lives of the dinosaurs have been a dark mystery.
01:14Probably the least researched and most misunderstood part of dinosaur behavior is sex.
01:21Mere bones tell us little about acts of the flesh.
01:33At last, paleontologists such as Bob Baca are piecing together a complete picture of dinosaurs as creatures that pursued life
01:41with a passion.
01:50We're looking at their horns.
01:52We're looking at their hooters, the noisemakers in their snouts.
01:56Dinosaurs were as invested in sex as a bighorn sheep or a moose.
02:01Because without sex, you don't get your genes into the next generation.
02:05If you don't do that, you're a Darwinian zero.
02:08To pass on your genes, you first have to attract a mate.
02:12And the dinosaurs developed an array of sexual lures.
02:16Bright colors, elaborate displays, and come-hither gestures.
02:24You've got to advertise.
02:26The dinosaur world evolved very fast.
02:29Fast evolving animals advertise a lot.
02:33So there would be sonic advertisement.
02:35There would be visual advertisement.
02:37There would be in color.
02:38There would be in dance.
02:39There would be a full Broadway musical of courtship display.
02:48Such behavior was overlooked by early paleontologists.
02:58Here's a gallery of some of the great dino thinkers of this country.
03:01Professor Marsh of Yale, he found Triceratops.
03:05Professor Osborne, he found T-Rex.
03:07Dr. Barnum Brown dug dinosaurs all over the world.
03:10S.W. Williston ran the department at Chicago.
03:13Now these guys thought about attack, predators and prey.
03:17They thought about chewing, how a horse or a brontosaur would chew plants.
03:22They thought about locomotion.
03:24They thought about climbing mountains and digging holes.
03:27But they didn't think about sex.
03:30It was verboten nearly totally.
03:34Early paleontologists barely scratched the surface of dinosaur behavior.
03:39To them, the extravagant array of dinosaur horns was used strictly for attack or defense.
03:55These sex-free dino thinkers weren't letting dinosaurs be real, living, breathing animals.
04:01Here's a real, living, breathing animal.
04:03It's a bighorn sheep.
04:04It's a complete animal.
04:05It eats plants.
04:06It runs away from predators.
04:07But it's also thinking about courtship, about sex.
04:12It's literally got sex on the brain.
04:14These horns, which dominate the skull architecture, are for ramming other bighorn sheep during courtship contests.
04:21And what the dino thinkers didn't let dinosaurs do is grow things for sex.
04:30Dinosaurs, like modern bighorn sheep, developed headgear for the same reasons.
04:35To intimidate rivals and impress a mate.
04:43Mighty T-Rex, it seems, also had sex on the brain.
04:47Bony ridges on top of the skull were well-suited for battling rivals head-to-head over a potential mate.
04:56If you have great genes, if you're a Tyrannosaurus rex and your genes are the best possible for running and
05:04killing prey,
05:05it's still no use at all if you can't get those genes out there and mix them with the genes
05:12of another T-Rex of the opposite sex
05:15and make little rexlets in the next generation.
05:19T-Rex has sort of a bony football helmet behind the eye, as a cushion for the eye and the
05:26brain,
05:26along the snout through these raised, roughing edges that in life would be covered with very tough skin.
05:34Of course that's for whacking.
05:36To imagine two T-Rexes whacking heads with each other in sexual combat?
05:41Just watch these woolly bison go at it.
05:45Now picture the same scene replayed with creatures who weighed up to eight tons.
05:53The Pachycephalosaurus, too, seemed to have a head for sex.
05:56It towered ten feet above the ground and likely used its enormous ten-inch thick brain case to batter sexual
06:03rivals.
06:07The domed head would identify it to the opposite sex as a strong mate.
06:15The crowning touch in sexual headgear belongs to the breed of dinosaurs known as the Ceratopsians.
06:21Especially the most famous of them, Triceratops, named for its three horns.
06:26When paleontologists found Triceratops in the same layers of earth as T-Rex, they assumed the frills and horns were
06:34defensive structures.
06:37But as other Ceratopsians came to like, their elaborate headgear was not so easily explained.
06:43They were too widely varied to be used simply for defense, too fragile for anything, attack, defense, or sexual head
06:51-butting.
06:56To learn why the dinosaurs had such elaborate headgear, paleontologists looked to modern animals.
07:05Antelopes developed many sizes and shapes of horns, but not for attack or defense.
07:10The horns signal their sexual maturity to mates and intimidate would-be rivals.
07:20Ceratopsian dinosaurs, like Pachyrhinoceros, developed different headgear at different stages.
07:33Paleontologist Darren Tankey of the Royal Tyrrell Museum of Alberta, Canada, studies Pachyrhinoceros fossils for clues to the animals' age
07:41and sex.
07:44What we have here are three casts of reconstructed skulls of Pachyrhinosaurus.
07:49This one which we believe to be a female, this a male, and this a juvenile.
07:57The frill on the juveniles and young adults have this simple pie-crust-edge type effect.
08:03And in the adults, we have some very large horns developing on the back of the frill.
08:09These do not develop until the animal reaches full adult size and presumes sexual maturity.
08:15And previously it was believed these horns were for protection only.
08:20I think it's now very clear that this is Mother Nature's way of saying that
08:24A, I am a male or female Pachyrhinosaurus, and B, I am of breeding age.
08:32The sex of the Pachyrhinosaurus is anyone's guess until it reaches adulthood and develops headgear.
08:37Paleontologists believe the adult female's horns are less ornate than the longer and more pronounced horns of the full-grown
08:45male.
08:50X-rays reveal another clue to the sexual habits of ceratopsian dinosaurs.
08:54Dr. Bruce Rothschild, a Youngstown, Ohio rheumatologist, collaborates with Darren Tankey on dinosaur research.
09:03A specialist in human arthritis, he sees evidence of stress fractures in the foot bones and rib bones of ceratopsian
09:11dinosaurs.
09:12Injuries that he thinks were caused by stomping the ground during courtship and being butted in the side by sexual
09:18rivals.
09:21We see this phenomenon in bison, where there is a side budding behavior in territorial disputes, in courting rituals,
09:29and this seems to be basically the same phenomenon in the ceratopsian dinosaurs.
09:35Those dinosaurs without elaborate headgear, like the giant brontosaurs, may have advertised their intentions with color,
09:44turning themselves into walking billboards for sex.
09:47Baca thinks the largest dinosaurs, unlike large land animals today, were quite colorful.
09:56The reason big animals today are gray is because they are color blind.
10:00They don't see in colors.
10:03They're big mammals.
10:03Big mammals are color blind.
10:04But birds see color.
10:06Well, alligators and crocodiles see color too.
10:09So do lizards.
10:09You see a panoply of bright colors in fish and frogs.
10:13Did dinosaurs see color?
10:14Their eyes were built like birds, mostly, a little bit like crocs.
10:19And they must have seen a full range of reds and yellows and blues.
10:23So, of course, a bull brontosaurus would have some iridescent blue around its eye,
10:29maybe a ring of yellow and red around its throat to advertise itself.
10:33The most elaborate assortment of crests and colors belong to the duck-billed dinosaurs,
10:39like Critosaurus, whose classic profile earned it the name Noble Lizard.
10:46Its cousin, Saurolophus, used a two-foot head spike to get itself noticed.
10:56The fan-shaped hollow crest of the Lambiosaurus surely made it stand out in a crowd.
11:05But the most prominent of the duck-billed dinosaur crests was that of the Parasaurolophus.
11:13Of all the extravagant sexual displays, this was the most baffling.
11:21Weighing up to four tons, the mighty vegetarian was endowed with a six-foot hollow crest.
11:30This majestic headgear mystified David Weishemple,
11:34a paleontologist from Johns Hopkins University.
11:38The crest itself is very, very fragile.
11:41It's built out of very thin bone.
11:43Probably couldn't withstand a lot of this head-to-head stuff like you see in bighorn sheep.
11:48Because many Parasaurolophus fossils had been found in marine sediment,
11:53many paleontologists suggested the horn was used as a snorkel when the giant beast went swimming.
12:02But a Swedish paleontologist named Carl Viemann solved the mystery.
12:10Carl Viemann in Uppsala got himself a duck-billed dinosaur with a hollow crest.
12:16He looked at it and said, it looks like a trombone.
12:18It was a trombone.
12:20It was for making loud courtship noises.
12:22David Weishemple wondered what the 70-million-year-old love song of the Parasaurolophus sounded like.
12:29He knew that when the animal exhaled, the air would shoot up the windpipe
12:34to the back of the crest into the throat and out the snout.
12:39Weishemple built himself a horn as long as the crest and taught himself to play it.
12:45Well, this contraption that I've got in my hands here is, in fact, a model of the crest of Parasaurolophus.
12:51It's the right size and the right shape for Parasaurolophus.
12:55It's built out of PVC tubing.
12:57And the reason I built it was to get a better senses to the kinds of sound that Parasaurolophus would
13:01have made.
13:02So why don't I play it for you?
13:15This unique love song no doubt made the Parasaurolophus the diva of the dinosaurs.
13:20Using the trombones in their heads, they serenaded mates and repelled rivals.
13:29After all the singing, stomping and head-butting was over, the dinosaurs finally got down to some real romance.
13:41Just how they did it, the fossils don't say, but some scientists have reached their own conclusions.
13:47The late Beverly Halstead, a British professor of geology and zoology, was noted for his candid theories of dinosaur sex.
13:57He speculated that the male mounted the female from the rear, twisting the tail under hers to align the sex
14:05organs.
14:09The male would have to keep one foot on the ground to avoid crushing the female during mating.
14:21Halstead not only published his theories, he famously demonstrated them in his lectures.
14:27The part that we're interested in is about there. That is the critical part.
14:31So if we take up the same position again, down the front, of it like this,
14:36imagine now that I have a tail coming here, and my hand is doing, I can actually get under, twist
14:42my tail,
14:43she can twist her tail, and we can get two cloaca into direct, correct position.
14:50Thank you. Thank you very much.
14:57This precarious three-point stance seems to work for most dinosaurs.
15:03But consider the Stegosaurus.
15:06It literally points out the problem with Halstead's theory.
15:13How the male Stegosaurus felt the next morning, no one can say.
15:23By all accounts, the impressive size of the dinosaurs was not matched by the size of their sex organs.
15:30Like modern reptiles, male dinosaurs had no true penis.
15:39The sex organ, called the cloaca, is set back beneath the tail, as it is in birds and lizards.
15:48Some male dinosaurs had a specialized bone at the base of the tail to maneuver the cloaca into position.
15:57The chevron bone of the mighty male T-Rex, for example, is a mere eight to ten inches long.
16:03And Halstead claimed that the sex organ of a four-story, seventy-foot-long brontosaur
16:08would have been, at best, a mere foot and a half in length.
16:17Darren Tankey believes that he had found proof that dinosaur sex was not only awkward, but hazardous.
16:25Literally hundreds of broken and re-healed spines on the tails of the duck-billed dinosaurs.
16:33You can see large, bony growths, and when you look at it, and on, you can see that the neural
16:39spine, this process right here, has been bent and twisted.
16:42And from looking at it, I can see at least two or three different fracture sites that have mended, they've
16:49been re-healed.
16:51Some scientists have proposed an obvious solution.
16:55Duck-bills were social animals, getting in each other's way and stepping on tails.
17:00Except that the breaks were more common at the base of the tail, not the tip.
17:07Others proposed near misses with T-Rexes. These were the duck-bills that got away.
17:16But Tankey sees these healed breaks in half of the duck-billed dinosaur fossils he studies.
17:30Now when you look at these, you can actually try to, and begin to establish how they may have been
17:36formed.
17:37And it looks like a great weight has pressed down on them from above.
17:43It's either that or the animal's laying on its back and collapsing under its own weight.
17:48But I cannot see any reason why an animal would be doing that.
17:56Paleontologist Lou Jacobs has conducted extensive digs in Texas.
18:00He considers Tankey's theory improbable.
18:04I don't think that makes too much sense.
18:07Because, you know, the point of sexual reproduction is to have offspring.
18:15And there needs to be some sort of element of pleasure in it.
18:19And I don't think breaking your tail is a particularly pleasurable thing or adaptive.
18:25And I doubt that it happened too much, if at all.
18:29Even if sex for the dinosaurs wasn't much fun, it clearly worked.
18:34So what were the dinosaurs like as parents?
18:41Until recently, paleontologists assumed they were like many modern reptiles.
18:47They laid their eggs and moved on.
18:51But now, tiny bones of baby dinosaurs are emerging and casting their parents in a different light.
19:05As we learn more about the sexual habits of dinosaurs, our picture of them is changing.
19:12Jack Horner of the Museum of the Rockies in Bozeman, Montana has done a lot to bring that about.
19:25Horner is a fossil hunter's Indiana Jones.
19:29He has found more dinosaur bones than anyone.
19:33But he has never found the fossils of an infant dinosaur.
19:47One day, quite by chance, Horner stopped at a rock shop near Shodo in northern Montana.
19:52In the nearby Badlands, the owner had found tiny bones she could not identify.
19:58She asked Horner to take a look.
20:01Horner realized he had stumbled onto the very thing he had been looking for.
20:06The bones of dinosaur young.
20:11With a team of graduate students, Horner immediately began excavating the site where the bones had been discovered.
20:17What they found was not just baby fossils, but an entire nesting ground and scores of fossilized dinosaur eggs clustered
20:26together.
20:31The site would become known as Egg Mountain.
20:34And it was here that Horner would change forever the image of dinosaurs as monsters.
20:44These dinosaurs had cared for their young.
20:50They literally couldn't walk.
20:52They may have been able to stand up.
20:54Babies couldn't walk.
20:55They couldn't have left their nest.
20:57So, we at least know that they were, that food was brought to them.
21:02Horner named the species of duckbill dinosaur that had nested at Egg Mountain the myosaur, meaning the good mother lizard.
21:13Like colonies of nesting birds today, the myosaur gathered in huge numbers at Egg Mountain, scooping out nests 30 to
21:1940 feet apart.
21:20The length of an adult duckbill.
21:28Sixty million years later, the fossil impression of dinosaur nests are still visible where mothers once tended their crowded nurseries.
21:39And what's really nice about this nest is that we have the rim of the nest is preserved.
21:46You can actually see that the dinosaur had dug out probably with its feet or something, or its little hands,
21:55dug out a pit, a mud pit, and then laid the eggs.
22:03This particular kind of dinosaur we call Orodromeus.
22:07And it's a small plant-eating dinosaur, would have been about six to seven feet long.
22:13The good mother dinosaurs of Egg Mountain underscore the new image of dinosaurs as living, breeding animals.
22:21For modern paleontologists, this new image breathes fresh life into these ancient fossils.
22:36Finding dinosaur eggs and dinosaur babies changed the way people looked at dinosaurs because people had always looked at dinosaurs,
22:43well, they'd looked at dinosaurs two ways.
22:46They'd looked at them as large adults, and they'd looked at them as skeletons.
22:51I mean, our museums portray dinosaurs just as skeletons.
22:56Dead things stood up.
22:58And the baby dinosaurs, the eggs, finally brought life to them.
23:04And now we have a sense of the complete dinosaur from hatchling to mature sexually active adult to old grandmother.
23:14The love lives of the dinosaurs have given us our first complete picture of these fantastic creatures.
23:23They flirted and they fought.
23:27They tooted their horns.
23:33And they flaunted their sexuality with colorful abandon.
23:38From the buried secrets of dinosaur sex has come a new awareness.
23:44That the swamps and forests where they lived were not only places of terror.
23:49They were places of primordial passion.
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25:02Transcription by CastingWords
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