. The dinosaur book : the ruling reptiles and their relatives. Dinosaurs; Reptiles, Fossil. the backbone in this animal was strength- ened by the lengthening of the sacrum, so that an additional vertebra became attached to the upper hipbones, the ilia. Compare this with the comparatively small attach- ment between the backbone and the hips in little Ornitholestes. It is in the great sauropods, however, that we see the most advanced adaptations to large size. These huge dinosaurs, 70 or 80 feet in length and weighing 20 or 30 or 40 tons, must have experienced problems in mechanics that have nev
. The dinosaur book : the ruling reptiles and their relatives. Dinosaurs; Reptiles, Fossil. the backbone in this animal was strength- ened by the lengthening of the sacrum, so that an additional vertebra became attached to the upper hipbones, the ilia. Compare this with the comparatively small attach- ment between the backbone and the hips in little Ornitholestes. It is in the great sauropods, however, that we see the most advanced adaptations to large size. These huge dinosaurs, 70 or 80 feet in length and weighing 20 or 30 or 40 tons, must have experienced problems in mechanics that have never before or since plagued a land-living animal. So it is that the limbs in these dinosaurs were heavy and postlike and the individual bones were extraordinarily massive and dense—veritable pillars for the support of the animal. Likewise, the feet of these giant sauropods were short and broad, so that they formed massive, round pediments through which the weight of the body was thrust against the earth. Like the lacy trusses of a cantilever STRENGTH AND LIGHTNESS simul- taneously achieved: a bone from the neck of the giant sauropod dinosaur, Brontosaurus. Note the concentration of bony material along lines of stress and the formation of hol- lows in other portions From Osbom and Mook, 1921. bridge, the backbone of Brontosaurus stretched between the strong abutments of the limbs and their girdles, and beyond, to form the neck and the tail. Here was a problem that required for its solution strength combined with lightness; strength upon which to hang the many tons of body, neck, and tail, lightness so that the vertebral column itself, necessarily large because of the needed strength, would not be over- burdened by a great amount of "dead weight" of bone. The problem was solved by the inexorable processes of evolution, so that the vertebrae became "excavated" where bone wasn't needed. In other words, bone was formed along the lines where stresses would come a
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Keywords: ., bookauthoramericanmu, bookcentury1900, booksubjectreptilesfossil
