Spinosaurus is rapidly gaining on Tyrannosaurus Rex as the world's most popular carnivorous dinosaur. Here are 10 things you may or may not have known about this giant, sailed theropod. (See also a gallery of Spinosaurus pictures)
1. The original fossils of Spinosaurus were destroyed in World War II.
The German paleontologist Ernst Stromer von Reichenbach discovered the remains of Spinosaurus in Egypt shortly before World War I--and they wound up in the Deutsches Museum in Munich, where they were destroyed by an Allied bombing raid in 1944. Since then, experts have had to content themselves with plaster casts of the original Spinosaurus fossils. (Read more about the discovery of Spinosaurus.)
2. Spinosaurus was bigger than T. Rex.
Pending further discoveries, Spinosaurus is the current record-holder in the "world's largest carnivorous dinosaur" category: full-grown, 10-ton adults outweighed Tyrannosaurus Rex by about a ton and Giganotosaurus by about half a ton. Since so few Spinosaurus fossils are extant, it's possible that other individuals were even larger--though for now that's just speculation.
3. The skull of Spinosaurus was unusually long and narrow...
Despite its rough similarity to T. Rex, there was no mistaking Spinosaurus for your average tyrannosaur. Besides its prominent sail (about which more below), Spinosaurus' skull was long, narrow and distinctly crocodilian in profile, and studded with relatively short (but still sharp) teeth. In fact, the skull of Spinosaurus was six feet long, meaning it could have swallowed the average human being whole!
4. ...probably because it fed on fish.
The shape of Spinosaurus' skull--combined with the fact that it lived along the north African shoreline--has led paleontologists to surmise that it (at least occasionally) speared fish out of the water, in addition to hunting down and killing smaller dinosaurs. It's even conceivable that this huge predator pursued a strictly aquatic diet, which would make it the top fisher-lizard of the middle Cretaceous period.
5. The closest relatives of Spinosaurus were Suchomimus and Irritator.
Suchomimus ("crocodile mimic") and Irritator (so named because the paleontologist examining it was having a bad day) both resembled a vastly scaled-down Spinosaurus. In particular, the long, narrow shape of these dinosaurs' jaws hint that they inhabited a similar fish-eating niche in their local ecosystems, the first one in Africa and the second in South America.
6. No one knows why Spinosaurus had a sail...
Over and above its size and the shape of its skull, Spinosaurus' most notable feature was the elongated sail along its back. This sail may have been a sexually selected characteristic (that is, Spinosaurus males with bigger sails had a better chance of mating with females), or it may have helped regulate this dinosaur's body temperature. (For more, see Why Did Spinosaurus Have a Sail?)
7. ...but we do know it was supported by "neural spines."
Spinosaurus' sail wasn't simply a flat, oversized outgrowth of skin that flopped wildly in the Cretaceous breeze and got tangled in dense underbrush. This structure grew on a scaffold of scary-looking "neural spines," long, thin projections of bone--some of which attained lengths of nearly six feet--that jutted out from this dinosaur's individual vertebrae.
8. Spinosaurus may have occasionally tangled with Sarcosuchus.
Spinosaurus shared its northern African habitat with Sarcosuchus, aka the "SuperCroc"--a 40-foot-long, 10-ton prehistoric crocodile. Since Spinosaurus fed mostly on fish, and Sarcosuchus spent most of its time half-submerged in water, these two mega-predators must have occasionally crossed paths. (For more on this encounter, see Spinosaurus vs. Sarcosuchus - Who Wins?)
9. Spinosaurus may have been an occasional quadruped.
Based on the size of its front limbs--much longer than those of a comparable T. Rex--some paleontologists think Spinosaurus may have occasionally walked on all fours. Combined with its piscivorous diet, this would make Spinosaurus a mirror-image of contemporary grizzly bears, which are mostly quadrupedal but occasionally rear up on their hind legs when threatened.
10. Spinosaurus wasn't the only sail-backed dinosaur.
Nearly 200 million years before Spinosaurus, Dimetrodon (not technically a dinosaur, but a synapsid reptile) sported a distinctive sail along its back. And a close contemporary of Spinosaurus was the north African Ouranosaurus, a hadrosaur (duck-billed dinosaur) equipped with either a true sail or a thick, fatty hump of tissue that it used to store fats and liquids (like a modern camel).