How to Build a Dinosaur

Today’s film project is to construct a dinosaur from a pile of bones right on camera in the courtyard of Li Daqing’s laboratory workshop. In this case the dinosaur is a very large one, Daxiatitan, which reaches a length of 90 ft., although this one mercifully was a little bit shorter at about 70 ft. Is it possible for Daqing’s men to assemble a skeleton in one working day? I know it is, because I saw his men assemble 10 skeletons in three days last summer. I thought this would make pretty interesting television, as you will see when you tune in next May.

How many bones does a 70 ft. sauropod have? Possibly the same number as a 30 footer, 50 footer or 90 footer. If we start with the vertebrae, there are 16 cervicals in the neck (yes, twice what a giraffe has plus two), 13 in the rather short back region (we call them dorsals because dinosaurs almost never have lumbar vertebrae), 5 sacrals and about 56 caudals in the tail. Underneath the tail vertebrae there hang down about 45 slingshot-shaped chevrons that start out large near the pelvis, diminish in size towards the end and then disappear altogether. How is your math so far? I think we are up to 135 bones so far. For ribs there are 13 pairs in the neck, and13 pairs in the back for a total of 52 more bones, bringing us to 187, and we haven’t even gotten to the legs yet. The shoulder girdle has two pairs of bones (adding a coracoid) instead of the single scapula of mammals, but the pelvis has the same three pairs of bone; thus four in front, six behind for a total of 10 more bones – 197. Oh, there is a pair of large kidney-shaped sternal plates near the bottoms of the ribs just behind the shoulder. 199.

Phil and Peter with some big bones

Phil and Peter with some big bones

The long bones of the limbs are identical to mammals – three pairs for the forelimb, three for the hind limb (see how easy anatomy is?!). We now have 211 bones. Hands and feet are complicated – there are five pairs of metacarpals and five pairs of metatarsals, for 20 more – 231 bones. The toes of sauropods are short and stubby, with a severe reduction in the number of segments in each digit, although there was a large claw on the inner toe both front and rear. The total number of phalanges both fore and aft is about 30 – 261 bones. There are a very few wrist and ankle bones, also much reduced, say a total of 4 for 265 bones. We could count each bone in the skull like real anatomists do, but let’s be lazy and score 1 for the skull and jaws and top our count off at 266 bones for Daxiatitan.

 

Bone puzzle

Bone puzzle

Is it possible to mount 266 bones in one day? Yes, if you are a member of Li Daqing’s splendid team of workers and if Phil and Peter don’t get in the way too much. There are several secrets that I will reveal to my privileged readers. One is that the skeleton is a cast of the real bones, not the fragile and precious bones themselves. The other is that casts were cleverly designed to be taken up and dismantled for traveling exhibits. Today each of the 90 vertebrae did not have to be painstakingly joined to its neighbors. Rather long stretches of verts were cast as single units—the tail in two units, the heavy sacrum as one, the back as two units and the neck as two units. Internal steel runs the length of each unit, and one unit slots neatly into the next—just like the toy models we assembled as kids, only much much larger and heavier.

As the bone pile was dissected by the workers, the heavy sacrum was carried into its carefully predetermined position in the middle of the court yard. A crane hoisted the unit up into the sky, 12 or so feet above the ground. Next, a pre-assembled hind limb unit (femur, tibia and fibula) was carried over and coaxed into a vertical position. Ideally the metal projection at the end of the femur would have slotted directly and painlessly into the awaiting socket in the sacrum (I am speaking now in engineering not anatomical terms); however the dangling sacrum was free to twist and spin, and spin it did. Scaffolding was quickly erected and soon workers were scrambling all over, oblivious of the height off the ground. After about 20 minutes of wrangling and cajoling both from the ground and from the scaffold, the femur was finally persuaded to slide into its intended socket, aided by a coating of grease on the metal fitting. It was then bolted into position. The process was repeated on the other side and success was achieved a little more quickly. The men carried over the first section of tail with attached chevrons, the tail was lifted by the crane, and union was achieved fairly quickly. Likewise for two sections of dorsal vertebrae. The skeleton was starting to look like something!

Necking with dinosaurs

Necking with dinosaurs

The forelimbs were a little more challenging although once again clever design was evident. The second rib was attached and bolted in (each of the 26 dorsal ribs is separate). It clearly showed sockets for attachment of the scapula. The large scapula with attached coracoid was hoisted into position by the crane, and it was evident that the inside surface had the first rib already joined to it. When the first rib was finally joined into its socket and bolted, and the second rib and the scapula united, the desired structural (not anatomic) union was achieved. The single forelimb unit was wrestled into the socket in the shoulder. None of these were easy because the limbs were heavy due to large size and heavy constituents of plaster and steel. When this operation was accomplished on the other side, four legs clearly supported a torso. In three and a half hours a crew of 14 men accomplished a great deal. A lunch break was well earned. After lunch, the operations were relatively straight forward: slot in the neck, finish the tail, hang each of the ribs, put the three separate pelvic elements in one-by-one on each side, attach hands and feet (four units), add the sternal plates. The final flourish was the hanging of the head, executed with theatrical flair. What a performance! Invite them to your next birthday party! The script called for completion before dark at 6 p.m. It actually topped out at 4:30 p.m. And to think, they even did it in Chinese!

Pete's dragon

Pete's dragon

So this my friends, is how to build a dinosaur. Carefully, slowly, safely, correctly. It really does help to have 28 pairs of skilled hands, a crane and a lot of scaffolding. Our finished product is 70 ft. long 12 feet at the hips, and the head is browsing in a tree 20 feet up. It is truly a sight to behold.

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1 Comment

  1. Sara ElShafie said,

    October 24, 2009 at 2:18 am

    “Pete’s Dragon,” I love it!! That is some admirable work done with admirable speed! How much did the largest bone casts (femur or humerus, perhaps?) weigh?


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