Fossil footprints are the only direct evidence left by locomoting dinosaurs

lovethee Articles

Working on my undergraduate thesis, I had toyed with the hypothesis that the dinosaurs’ shoulder blades might have swung across the ribcage, but I was unable to build a reliable support for such heterodox mechanics. (lfe size animatronic dinosaur)Later, at graduate school, I met a fellow student, Jane Petersen, who had just completed a thesis about the shoulders of chameleons. She proved that chameleons could swing their long shoulder blades fore and aft more freely than other lizards, because the chameleon’s blade was not locked onto the chest by a bulky collarbone.

 

This impressed me because I had already noticed that chameleons were the only lizards that looked like dinosaurs in the shoulders. Both dinosaurs and chameleons have very long, slender shoulder bones that work completely free of restraint from the collarbone, which anchored the shoulder blades in all most primitive reptiles.(dinosaur factory) Chameleons evolved from some “normal” lizard ancestor that possessed a thick, stiff collarbone which held the shoulder blade in place. But chameleons shed that collarbone along their evolutionary path to provide themselves with more participation from their shoulders in the strokes of their fore-limbs. (life size dinosaur for sale)Dinosaur evolution must have been the same—dinosaurs experienced the same reduction of the collarbone and must have developed a similar free-swinging shoulder. And the big quadru-pedal dinosaurs evolved the longest shoulder blades of any verte-brate, past or present. As its yardlong shoulder swung alongside Triceratops % ribcage, the extra length added to its forelimb must have given the animal a grand propulsive boost. Both fore- and hind limbs were consistently designed for fast, maneuverable movement.

 

 

Such outlandish heterodoxy proves doubly sweet when supported by independent confirmation. (animatronic dinosaur costume)Fossil footprints are the only direct evidence left by locomoting dinosaurs, so a set of tracks left by some speeding Tyrannosaurus would provide dramatic confirmation. The English biologist McNeil Alexander has worked out a clever formula for computing speed from trackways: all that is necessary is the length of stride and the toe-to-hip measurement. (lifelike dinosaur for sale)When first applied to some samples of dinosaur prints, the formula yielded low speeds—two to four miles per hour. Some commentators immediately jumped to the conclusion that this conclusively proved the theory of slow dinosaurs.

 

That is nonsense. Most fossil trackways represent slow cruising speeds, not top speed, because all species spend most of their time moving along in an unhurried fashion. Bursts of maximum velocity erupt only rarely, when a predator charges or a plant-eater scampers for its life. Most tracks left by gazelles and rhinos today are made at a slow speed when these animals are feeding or going to or from water holes. Rhinos don’t live their entire lives at thirty-five miles per hour; a trackway that caught one of these rare moments when the rhino was galloping full tilt would be a most extraordinary find. Trackways from big quadrupedal dinosaurs are rare—there exist only four sites with good brontosaur tracks—so the sample is far too poor to argue any case about top speed.