Robert T Bakker

by The Dinosaur Heresies (pdf)

  angiosperms possessed adaptations that were new and potentially

  revolutionary. But they needed some edge—an opening for

  breaking out of the confines imposed by the older groups to start

  proliferating species. Herbivorous dinosaurs gave them that initial

  break.

  Flowering plants and low-feeding beaked dinosaurs must have

  co-evolved in a mutually beneficial way. As more and more new

  kinds of Cretaceous beaked dinosaurs entered the system, more

  and more angiosperm families evolved. From the meek beginning

  of a few Early Cretaceous species, the angiosperms grew into a

  mighty clan by the Late Cretaceous, boasting more species than

  conifers and cycadeoids combined. When the Cretaceous ended,

  massive extinctions again swept through the terrestrial habitats.

  Cycadeoids disappeared, but angiosperms not only survived, they

  increased their share of the species count in epoch after epoch down

  to the present day.

  Modern angiosperms no longer depend upon intense low

  feeding for their advantage over conifers and ferns. They now

  contain hundreds of specializations for every habitat from tall cli-

  max forests to swamps and deserts, windswept mountain meadows

  and bare rock faces. But in those first critical years of their evo-

  lutionary history, the angiosperms were struggling newcomers.

  Square snouts and pincerlike beaks helped the flowering plants beat

  the floral competition and establish the angiosperms as the fastest-

  evolving plant group. There was of course no plan in this. Stego-

  WHEN DINOSAURS INVENTED FLOWERS I 197

  saurus didn't die out purposely to permit its low-cropping cousins

  to take over and make the world fit for flowers. Wide-mouthed

  ankylosaurs didn't plan to munch down the competition. It was all

  serendipitous. Nonetheless, because of the way they suffered ex-

  tinction and then rebuilt their herbivorous groups, the dinosaurs

  played a central role in one of the grandest dramas of the flora. In

  their way, dinosaurs invented flowers. Without them, perhaps our

  modern world would yet be as dull green and monotonous as was

  the Jurassic flora.

  198 I THE HABITAT OF THE DINOSAURS

  PART 3

  DEFENSE,

  LOCOMOTION,

  AND THE CASE

  FOR WARM-BLOODED

  DINOSAURS

  10

  THE TEUTONIC

  DIPLODOCUS: A LESSON IN

  GAIT AND CARRIAGE

  nyone who doesn't believe that God was looking out for

  A

  America at the turn of the century should look at the dates

  of key American victories in war and science. On July 4, 1898,

  Admiral Sampson announced a "Birthday present for the Nation,"

  the complete victory of the fleet over the Spanish squadron in Cuba.

  (Commodore Schley actually won the battle. Sampson was away

  conferring with generals—but claimed the credit.) On July 4, 1899,

  Arthur Coggeshall found Diplodocus carnegiei. On July 4, 1900, El-

  mer S. Riggs, hunting dinosaurs for Marshall Field's Chicago mu-

  seum, found the first-known Brachiosaurus, king of the brontosaurs,

  a giant that dwarfed even Brontosaurus excelsus.

  American museums were erecting dinosaur skeletons as fast

  as American shipyards erected new steel battleships to protect the

  fledgling star-spangled empire. Europe viewed both developments

  with mixed admiration and alarm. For a century Old World sci-

  entists had been digging and studying dinosaurs, but no one had

  found Jurassic giants nearly as complete as the ones that tumbled

  out of almost two dozen American quarries, starting in 1878. When

  the first Diplodocus, named for the American millionaire Andrew

  Carnegie who funded its discovery, arose on its metal scaffolding

  in Pittsburgh, John Bell Hatcher, in charge of the operation, di-

  rected the placement of the thigh bone into the hip socket very

  carefully. He drew upon the anatomical expertise of Marsh, Cope,

  THE TEUTONIC DIPLODOCUS: A LESSON IN GAIT AND CARRIAGE

  201

  Andrew Carnegie's ninety-foot-long

  Diplodocus from Sheep Creek, Wyoming

  and other Americans who had engaged in two decades of intense

  study. Hatcher decreed a vertical stride, with the thigh bone

  swinging fore and aft directly under the hips, for Diplodocus car-

  negiei. And the other American museums consequently agreed.

  Riggs's Brontosaurus went up that way in Chicago, as did Osborn's

  in New York. These Americans were convinced that the great di-

  nosaurs strode through their Mesozoic world with the upright gait

  and carriage that are characteristic of the biggest African elephants

  today.

  America, which had had to import all its scientific apparatus,

  and had sent its scholars to England and Germany for doctorates

  only decades earlier, now began to export scientific wealth.

  On one of his frequent visits in British high society, Andrew

  Carnegie met with Edward, Prince of Wales, the future Edward

  VII. Aware of Carnegie's enthusiasm for the exploration of dino-

  saur sites in Wyoming as an aspect of his new-found passion for

  public service, the Prince of Wales suggested Carnegie might be

  pleased to have his people find another Diplodocus for the British

  Museum, which had no complete specimen.

  Back in America, William J. Holland, director of the Pitts-

  burgh Museum, was aghast at Carnegie's request. New quarries not

  already being worked by other new American museums were ex-

  tremely difficult to find, and it would be impossible to guarantee

  quick delivery. Holland proposed a complete plaster replica in-

  stead. So, in due course, the Pittsburgh technicians assembled

  beautifully accurate plaster casts of Diplodocus carnegiei and shipped

  them to London complete with instructions for assembly. A char-

  acteristic American approach—the prefabricated, instant dinosaur

  kit. Soon Carnegie was besieged by envoys from Berlin, Vienna,

  and St. Petersburg for matching gifts of a Diplodocus. And Andrew

  was delighted to comply. Within a few years nearly every major

  European capital had its own prefab Diplodocus.

  Once assembled, most of these European Diplodocus replicas

  were posed in mid-stride, with the same high-hipped posture pre-

  scribed by Hatcher and the other American experts. This recon-

  struction bore important implications for dinosaur biology, precisely

  because no living species of reptile walked that way. Most pres-

  ent-day lizards scuttle over the ground with their thighs sticking

  out sideways. Their hind limb strokes back and forth in horizontal

  THE TEUTONIC DIPLODOCUS: A LESSON IN GAIT AND CARRIAGE I 203

  arcs, parallel to the ground. Hence, these modern lacertilians are

  decidedly low-slung in posture, with a ground-hugging configura-

  tion that allows them only slight clearance. Crocodilians and cha-

  meleon lizards are a bit more upright in carriage, raising their bellies

  higher off the trackway. Yet their elbows and knees still stick out

  sideways more than those of an elephant, rhino, or most other large

>   mammals. Endowing the Diplodocus with elephant-style posture was

  therefore a clear statement that the biomechanics of dinosaurs were

  unlike those of any living reptile. Diplodocus's posture as envi-

  sioned by Hatcher, Osborn, and Riggs was equal to the most ad-

  vanced mammalian adaptive machinery.

  Enter the Germans. No culture had a more illustrious nine-

  teenth-century tradition of paleontological scholarship. A Ger-

  man, Hermann von Meyer, had first recognized the unity of all

  the great Mesozoic creatures we now call dinosaurs. And German

  anatomists were acknowledged worldwide as the best in labora-

  tory dissections and microscopy. In the early 1900s, Germany was

  a new and ambitious nation, and it was perhaps to be expected

  that a certain chauvinism should manifest itself in many different

  areas, including the scientific. It was not surprising that German

  paleontologists didn't immediately accept the conclusions about the

  posture of dinosaurs advocated by the Americans. What was sur-

  prising was the condescending tone the Germans resorted to when

  they published their scathing criticism of Carnegie's Diplodocus. The

  Germans insisted that the Americans had missed the point when

  they put elephant's legs on a dinosaur. Diplodocus was a genuine

  reptile, the elephant a genuine mammal, and nature did not mix

  the two. Tornier, the dinosaur expert in Berlin, described his ver-

  sion of the corrected Diplodocus: it was portrayed in a slinking pose,

  with the thigh and arm sticking out sideways, and the belly close

  to the ground. The Berlin school proclaimed this was a proper

  reptilian posture for a proper reptilian body.

  The Americans did not concur. They had a well-earned na-

  tional reputation for a hard-headed approach to the functions of

  machinery. Hatcher had handled scores of fossil hip joints. He knew

  that Diplodocus's thigh had a cylindrical surface at the joint that faced

  predominantly upward and forward. Diplodocus's hip bone con-

  tained a deep socket at the joint, whose surface correspondingly

  faced mostly downward and backward. Put the thigh bone into the

  204 | DEFENSE, LOCOMOTION, AND THE CASE FOR WARM-BLOODED DINOSAURS

  Diplodocus in a rut. Carnegie

  Museum's Professor

  Holland poked fun at the

  German reconstruction of

  Diplodocus with its

  outspread knees. Holland

  remarked that the poor

  German Diplodocus would

  have had to find giant ruts

  to run in because its rib

  cage was so deep. (The

  diagram shows a cross-

  section view at the hip

  joint.)

  How Carnegie's men

  mounted Diplodocus. The

  Americans put together the

  hind limb the right way—

  with the thigh bone in a tall,

  erect posture.

  hip socket, and only one correct fit was possible: the hind leg stood

  vertically, with the knee facing directly forward. The Diplodocus's

  knee did not sprawl sideways like that of a "genuine lizard."

  American scholars, one after another, rebutted the arguments

  of the Germans. A key point all too often forgotten today was made

  in the course of this debate. Dinosaur biology cannot be recon-

  structed by assuming these beasts were merely "good reptiles."

  By 1920, the Great Trans-Atlantic War of the posture of Di-

  plodocus was over. The Americans clearly had the better of it. Ex-

  peditions from Berlin had found fabulous Brachiosaurus graveyards

  THE TEUTONIC DIPLODOCUS: A LESSON IN GAIT AND CARRIAGE | 205

  in German East Africa before World War I, and as the postwar

  research was published, the German scholars' restoration of Brach-

  iosaurus became like Carnegie's, with a nearly vertical, elephant-

  like posture. Incontrovertible evidence for the correctness of the

  Pittsburgh-style hip joint came during the 1930s and 1940s, when

  brontosaur footprints were found in abundance impressed into the

  Cretaceous limestone of Texas. The right and left hind prints proved

  to have been made very close to the trackway centerline, and

  therefore without question the two thighs had swung in great ver-

  tical arcs close to one another under the animal, exactly as Hatcher

  had reconstructed them. Indeed, all of the dinosaur fossil track-

  ways without exception showed the very same narrow-tracked gait,

  evidencing no splaying out of the knees. No dinosaur splayed its

  knees or toed out its feet. Duckbill dinosaurs actually toed in their

  hind feet, like enormous pigeons.

  Sad to relate, some modern reconstructions done in the 1960s

  and 1970s still portray dinosaurs everting their knees and planting

  their hind feet down, wide-set, with right and left hind paws spread

  far out to the side—like enormous lizards. An entire series of

  postcards in the British Museum reproduces paintings with such

  essentially dislocated dinosaur hips and ankles. Andrew Carnegie

  and Prince Edward knew better in 1906.

  As a student at Yale in the sixties, I observed that nearly

  everyone was restoring dinosaur hips with a mammal-type posture

  and narrow trackway. But the forelimbs were a different matter

  entirely. In the Great Hall of the Peabody Museum, trailing be-

  hind the nobel strides of Marsh's Brontosaurus excelsus, stood a finely

  preserved horned dinosaur, Centrosaurus. Professor Richard Swann

  Lull had mounted it in 1929- He had been with Osborn at Como

  and was highly regarded. He gave the centrosaur tall, erect hind

  limbs, but the elbows were mounted lizard-style, sticking out

  sideways, and the upper arms paralleled the ground. I marveled at

  this curious combination, which looked like two totally different

  locomotor apparatuses welded together at mid-torso. Further-

  more, Lull had also published a monograph on the horned dino-

  saur in which he employed this mismatched front end as an

  argument for a slow and plodding gait in these animals. But Marsh

  had already seen it otherwise as early as 1896. He had published

  drawings of horned dinosaurs with fully erect carriage in both fore-

  206 | DEFENSE, LOCOMOTION, AND THE CASE FOR WARM-BLOODED DINOSAURS

  quarters and hind. Marsh's Triceratops imparted a light-footed air

  to the huge three-horned beast, as though it were about to go

  trotting off the page, head down, to charge its mortal enemy, Ty-

  rannosaurus. Lull completely reversed Marsh's ideas about these

  forelimbs.

  But why had views on the forelimbs of dinosaurs changed? I

  could find no good reason. Smithsonian scientists endowed their

  Triceratops, a skeleton excavated by Hatcher, with bowed-out el-

  bows because, they said, the elbow's huge "funny bone" would be

  of use only in a sprawling posture. This made no sense to me. The

  "funny bone," properly called the olecranon, is a projection on the

  lower arm bone (ulna) to provide the elbow-opening muscles le-

  verage for their work. A large olecranon implies the elbow joint

  can be opened with great force. Now, turtles, crocs, and lizards

  pos
sess splayed-out elbows, but they all have short olecranons. The

  rhino's forelimbs stride vertically, and its olecranon is big. Tricer-

  atops possessed a large, rhino-style funny bone. Why wasn't Tri-

  ceratops accorded a rhino-style posture?

  Al Romer, the greatest dinosaur anatomist alive in the 1960s,

  explained the anomaly by arguing that evolution had worked faster

  on the hind legs than the fore. All primitive dinosaurs, as Romer

  told the story, had been two-legged bipeds, standing on hind limbs

  only. Thus when some families later dropped back down onto all

  fours, they didn't bother to rearrange their elbows to match their

  knees. This account was in all the textbooks, but I could not ac-

  cept it. Yale had a program—the Scholar of the House—in which

  an undergraduate could dedicate one full year exclusively to re-

  search. For my project, I focused on the problem of the alignment

  of the forelimbs of dinosaurs.

  It was a shoestring operation. My parents gave me a tiny

  handwound movie camera, and with Yale funds I bought the alli-

  gators and lizards that I kept in the museum basement. I'd lie on

  my stomach watching a lizard or 'gator walk around on an old rug,

  and built up a library of motion-analysis film of a dozen species.

  These filmings had their dangers. No three-foot 'gator was afraid

  of a Yale undergraduate, and I had to remember to move smartly

  when an open mouth filled the viewfinder. Usually I was in time

  to avoid having my nose bitten.

  Alligators are dinosaur uncles—relatives of the direct ances-

  THE TEUTONIC DIPLODOCUS: A LESSON IN GAIT AND CARRIAGE | 207

  The riddle of the mismatched legs. Living species have a range of postures—

  most lizards sprawl, crocodilians have a more upright, semierect stance, and

  most big mammals have a fully erect carriage. But orthodox dinosaurs—like

  Yale's Centrosaurus—had front ends that didn't align with the rear ends.

  tors of early dinosaurs—and as such they should be living repre-

  sentatives of the ancestral dinosaurs' forelimb arrangement. I was

  therefore surprised at the upright arrangement of the alligators'

  forelimbs. They kept their elbows close to their sides without

  spreading nearly as much as most lizards do. So I labeled this pos-

  ture "semi-erect," to set it apart from the "fully erect" posture of