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Three Cheers for Long-Necked Beauties!

Three Cheers for Long-Necked Beauties!


We don’t often think that extinct animals might have been examples of wonderful design, but they were! Even if we did reflect on extinct animals which were particularly well designed, we probably would not choose sauropod dinosaurs for that special category. Sauropod dinosaurs, you may remember, were the large plodding, four-footed specimens with long necks and long tails. They were probably the largest animals ever to have lived on land. They all grazed on plants. This was no doubt a good thing, since they probably were too slow to catch anything. So, you may well ask, what could be so special about these awkward looking creatures? Plenty!

The most amazing aspect of these creatures was their long necks, which reached truly amazing proportions. Camarasaurus, for example, which was a relatively small sauropod at 18 m (55 ft) long, had a neck about 2.7 m (8 ft) long balanced by a tail about 8 m or 25 ft long. Apatosaurus (famous for its original name of Brontosaurus, before it had the correct head attached to the rest of the skeleton), measured about 21 m (65 ft) long of which its neck was 4.5 m (15 ft) and its tail 7 m (24 ft). Then there was Mamenchisaurus with perhaps the longest neck of all. With its whole body length of 25 m (80 ft), it boasted a neck length of up to 14 m (46 ft), balanced by a tail which was even a little longer. The tails, of course, could drape downward without compromising the lifestyle of the animal, but the head would have to be held up in the air, supported by a horizontal or somewhat vertical neck. Therein lay some serious engineering challenges for these dinosaurs. It is not so easy to hold a long neck up in the air.

The problems of a long neck are as follows. Imagine for example that you have a vertical piece of wood. You want to attach a horizontal beam to the vertical structure. So, of course, you use lots of nails or screws to secure the second piece of wood at right angles to the vertical one so that you have a rigid board projecting from the vertical beam. Now suppose however that instead of a rigid board, you attach a string of wooden beads to the vertical structure. Do these beads stretch out horizontally the way the rigid beam did?  Of course not, the beads hang down. Similar engineering principles apply to long dinosaur necks. A rigid piece of bone would keep the neck elevated in the air, but of course (being rigid), it could not move. Alternatively, if the skeleton in the neck consists of separate bones, it would hang down, unless some cleverly engineered modifications are applied.

The design solutions which allow the long dinosaur necks to move, and yet stay elevated, are as follows. Firstly the skeleton in the neck consists of only a few component parts. Thus the neck bones (vertebrae) are very long, each up to 1.5 m (5 ft) long. This means that the average number of vertebrae (bones) in a sauropod neck is only about 12, while the average number of tail vertebrae might have been as high as 80. The lower number of component parts meant that less extra support was needed to keep the neck in the air.

Secondly the neck bones were exceptionally light but strong. Apparently the sauropod neck vertebrae were like those strong silvery helium balloons that we buy for celebrations. They had a very thin but strong layer of bone filled up by sacks of air kept under pressure from the lungs. It is easier to hold up a lighter structure than a heavier one and it certainly takes less energy to do so. The neck however would still hang limply if the component parts were not braced (provided with extra support). This is the third design feature. The beauty of bracing is that it allows for some support and some flexibility at the same time.

If you feel along your backbone, you will find small bumps marking the location of each vertebrae (back bone unit). These projections or spurs extend outward, but not very far in your case. In the case of some dinosaurs however, prominent spurs extended outward from each vertebra (imagine really big bumps along your back bone!) In the case of these dinosaurs, powerful ligaments connected the spurs together, thereby giving the whole backbone good support. This enabled any dinosaur with such a neck to enjoy considerable flexibility in the neck region along with adequate support to keep the head lifted upward. While such a neck was highly mobile however, the animal would have to work a little harder to keep its neck from wobbling. In addition, the bone spurs meant more weight to the neck, so these animals tended to have just moderately long necks. An example of such a dinosaur is Apatosaurus, formerly known as Brontosaurus.

The really long necks were braced on the other side of the backbone (in toward the internal organs). The bracing took the form of long thin pointy structures (called cervical ribs) which extended from one vertebra under several others in a row, thereby giving strength to the whole thing. These backbones tended to be very light, so extremely long necks were possible. The flexibility was not as great as for the other bracing design, but the neck was easier to keep from wobbling. Examples of such dinosaurs include Brachiosaurus, Camarasaurus and Mamenchisaurus. Diplodocus, on the other hand, is an example of a dinosaur whose neck was braced in both directions.

Thus we can see that the long necked style of dinosaur required some very special design features. Indeed some dinosaur experts have pointed this out. The Encyclopedia of Dinosaurs, edited by Philip Currie and Kevin Padian (1997) declares that the neck bracing provides “maximum strength for minimum weight – a true triumph of engineering.” (p. 654). Also Zdenek Spinar and Philip Currie tell us that the air filled neck vertebrae are “marvelously engineered structures for lightness and strength.” (in The Great Dinosaurs 1994). How very interesting these statements are. Everyone knows that engineered structures require an engineer, an intelligent individual who plans a structure for a particular purpose. In like fashion, engineered dinosaur necks have indeed been designed to solve several problems in managing these lengthy structures.

Of course the sauropod dinosaurs are now extinct and we are probably just as happy that this is so. They were however, wonderfully designed for their life style before the great flood. Apparently those that survived on the ark, have since been unable to cope with new conditions in order to survive to the present. We can still nevertheless appreciate how these creatures contributed to the richness and variety of the creation when they roamed the earth.

December 2009

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