Spinosaurus (meaning "spine lizard"):
Is a genus of theropod dinosaur which lived in what is now North Africa, from the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. This genus was first known from Egyptian remains discovered in 1912 and described by German paleontologist Ernst Stromer in 1915. The original remains were destroyed in World War II, but additional material has come to light in recent years. It is unclear whether one or two species are represented in the fossils reported in the scientific literature. The best known species is S. aegyptiacus from Egypt, although a potential second species S. maroccanus has been recovered from Morocco.
Spinosaurus may be the largest of all known carnivorous dinosaurs, even larger than Tyrannosaurus and Giganotosaurus. Estimates published in 2005 and 2007 suggest that it was 12.6 to 18 metres (41 to 59 ft) in length and 7 to 20.9 tonnes (7.7 to 23.0 short tons) in weight. The skull of Spinosaurus was long and narrow like that of a modern crocodilian. Spinosaurus is known to have eaten fish; evidence suggests that it lived both on land and in water like a modern crocodilian. The distinctive spines of Spinosaurus, which were long extensions of the vertebrae, grew to at least 1.65 meters (5.4 ft) long and were likely to have had skin connecting them, forming a sail-like structure, although some authors have suggested that the spines were covered in fat and formed a hump. Multiple functions have been put forward for this structure, including thermoregulation and display.
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| Size comparison of selected giant theropod dinosaurs, Spinosaurus (S. aegyptiacus) in red. |
Description
Spinosaurus is known for its neural spines, its large size, and its elongated skull.
Paleobiology
Function of neural spines
The function of the dinosaur's sail or hump is uncertain; scientists have proposed severalhypotheses including heat regulation and display. In addition, such a prominent feature on its back could also make it appear even larger than it was, intimidating other animals.
The structure may have been used for thermoregulation. If the structure contained abundant blood vessels, the animal could have used the sail's large surface area to absorb heat. This would imply that the animal was only partly warm-blooded at best and lived in climates where nighttime temperatures were cool or low and the sky usually not cloudy. It is thought that Spinosaurus and Ouranosaurus both lived in or at the margins of an earlier version of theSahara Desert, which could explain this. It is also possible that the structure was used to radiate excess heat from the body, rather than to collect it. Large animals, due to the relatively small ratio of surface area of their body compared to the overall volume (Haldane's principle), face far greater problems of dissipating excess heat at higher temperatures than gaining it at lower. Sails of large dinosaurs added considerably to the skin area of their bodies, with minimum increase of volume. Furthermore, if the sail was turned away from the sun, or positioned at a 90 degree angle towards a cooling wind, the animal would quite effectively cool itself in the warm climate of Cretaceous Africa. However, Bailey (1997) was of the opinion that a sail could have absorbed more heat than it radiated. Bailey proposed instead that Spinosaurus and other dinosaurs with long neural spines had fatty humps on their backs for energy storage, insulation, and shielding from heat.
Elaborate body structures of many modern-day animals usually serve to attract members of the opposite sex during mating. It is quite possible that the sails or humps of these dinosaurs were used for courtship, in a way similar to a peacock's tail. Stromer speculated that males and females may have differed in the size of the neural spine.
Finally, it is quite possible that the sail or hump combined these functions, acting normally as a heat regulator, becoming a courting aid during the mating season, being used to cool itself and, on occasions, turning into an intimidating device when an animal was feeling threatened.
Posture
Although traditionally depicted as a biped, it has been suggested since the mid-1970s thatSpinosaurus was at least an occasional quadruped. This has been bolstered by the discovery of Baryonyx, a relative with robust arms. Because of the mass of the hypothesized fatty dorsal humps of Spinosaurus, Bailey (1997) was open to the possibility of a quadrupedal posture, leading to new restorations of it as such. The hypothesis thatSpinosaurus had a typical quadrupedal gait has fallen out of favor, though spinosaurids may have crouched in a quadrupedal posture. Theropods, including spinosaurids, could not pronate their hands (rotate the forearm so the palm faced the ground), but a resting position on the side of the hand was possible, as shown by fossil prints from an Early Jurassic theropod.
Feeding
Spinosaurus is thought to have survived primarily on fish and scientists believe its eating habits resembled that of modern-day crocodiles. There is evidence that it lived on both land and sea.
The only direct substantiation that Spinosaurus ate fish was a juvenile discovered with fish scales and bones in its stomach. There is also evidence that it preyed on other small herbivore dinosaurs and scavenged.
Spinosaurus lived in Egypt and Morocco. There is speculation that the Sahara is rich withSpinosaurus fossils, but the harsh environment makes them difficult to unearth.
In popular culture
Spinosaurus appeared in the 2001 film Jurassic Park III, it replaced ''Tyrannosaurus'' as the main antagonist.The film's consulting paleontologist John R. Horner was quoted as saying: "If we base the ferocious factor on the length of the animal, there was nothing that ever lived on this planet that could match this creature [Spinosaurus]. Also my hypothesis is that T-rex was actually a scavenger rather than a killer. Spinosaurus was really the predatory animal." In the film, Spinosaurus was portrayed as larger and more powerful thanTyrannosaurus: in a scene depicting a battle between the two resurrected predators, Spinosaurus emerges victorious by snapping the tyrannosaur's neck.
Spinosaurus has long been depicted in popular books about dinosaurs, although only recently has there been enough information about spinosaurids for an accurate depiction. After an influential 1955 skeletal reconstruction by Lapparent and Lavocat based on a 1936 diagram by Stromer, it has been treated as a generalized upright theropod, with a skull similar to that of other large theropods and a sail on its back, even having four-fingered hands.
In addition to films, action figures, video games, and books, Spinosaurus has been depicted on postage stamps such as ones fromAngola, The Gambia, and Tanzania.
The creature has also appeared in documentaries such as Bizarre Dinosaurs, Monsters Resurrected and Planet Dinosaur.
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