An artist’s recreation shows (top to bottom) the skeleton, muscles, and living appearance of Deinosuchus.
Credit: © Tyler Stone

Paleontologists (scientists who study prehistoric life) learned more about a terrible crocodile this summer. A study by Adam Cossette of the New York Institute of Technology and Chris Brochu of the University of Iowa examined newly discovered fossil remains of the extinct crocodilian Deinosuchus. Crocodilians are group of reptiles that includes crocodiles, alligators, gavials, and caimans. The scientists published a revised description of the animal in the Journal of Vertebrate Paleontology.

Deinosuchus lived from about 82 million to 75 million years ago, during the late Cretaceous Period. Its closest living relatives are alligators. In most ways, it looked much like a modern alligator, except that it was enormous. Deinosuchus grew to a length of 33 feet (10 meters) or more and weighed about 8,000 pounds (3,600 kilograms). In comparison, the largest crocodilian alive today, the saltwater crocodile, reaches lengths of about 23 feet (7 meters) and weighs 2,200 pounds (1,000 kilograms).

Deinosuchus also lived like modern crocodilians. During the late Cretaceous, much of central North America was covered by a shallow sea. Deinosuchus lived in the vast wetlands on the edges of this sea. Like large crocodilians today, Deinosuchus was an ambush predator. It would swim over to an animal at the water’s edge, lunge out of the water to grab it with its powerful jaws, drag its prey into the water, and drown it. What was on the menu? Just about anything—including dinosaurs.

Numerous fossils of contemporary dinosaurs show bite marks from an animal that could only have been Deinosuchus. It even attacked large, meat-eating theropods (dinosaurs like Tyrannosaurus Rex) on occasion. But for the most part, these predators stayed out of each other’s way, much as lions and Nile crocodiles do in modern Africa.

Deinosuchus was not identical to modern crocodilians, however. it had a greatly thickened skull relative to its size. The thickness likely strengthened it for struggle against dinosaurs and other large prey. Deinosuchus also had a bulbous (rounded) snout, with two small openings at its tip. Paleontologists do not yet know what purpose these features served.

Deinosuchus wasn’t the only giant crocodilian. Sarcosuchus, which lived about 110 million years ago, may have reached 40 feet (12 meters) long, about the length of a bus. Another titan was Purussasaurus, which attained similar proportions during the Miocene Epoch, long after the dinosaurs went extinct.

Discovering a new kind of prehistoric animal is great, but learning more about one that has already been discovered is great, too! Deinosuchus is not a recent discovery. In fact, it was first described in 1909. But many of the fossils were incomplete. With the new material, Cossette and Brochu were able to uncover more about the animal’s lifestyle and better differentiate between the small handful of Deinosuchus species. In doing so, they paint a more complete picture of what the world was like tens of millions of years ago—and what a terrifying place it was!

May 19, 2014

Fossils from a massive dinosaur that was longer than two tractor-trailer trucks parked end-to-end and weighed more than 14 African elephants have been unearthed in the Patagonia region of Argentina. The 95-million-year-old fossils were found near La Fletcha, about 800 miles (1,300 kilometers) south of Buenos Aires, the capital. The yet-unnamed dinosaur may have been the biggest of the big–a new species of titanosaurus, the largest of the gigantic, long-necked dinosaurs called sauropods.

Sauropods walked on four stout, strong legs, much like those of an elephant. Nearly all sauropods had a long neck, a small head, a long tail, and a huge, deep chest and stomach region. Sauropods were the largest plant-eaters, feeding on the leaves of tall shrubs and of such trees as conifers. During the Cretaceous Period, they declined in importance in the Northern Hemisphere. But they remained the dominant plant-eaters in what are now South America, India, and Africa. Other supersized saurpods include Seismosaurus and Supersaurus.

A new sauropod discovered in Argentina may have been larger than Supersaurus (above), one of the largest dinosaurs to ever walk on Earth. (World Book illustration by John Francis, Bernard Thornton Artists)

The newly discovered sauropod was an estimated 130 feet (40 meters) long, weighed 88 short tons (80 metric tons), and stood 65 feet (20 meters) tall at the hips.  (By way of comparison, Tyrannosaurus rex was about 40 feet (12 meters) long, weighed about 7 short tons (6.3 metric tons), and stood about 12 feet (3.7 meters) high at the hips.)

The Argentine and Spanish paleontologists who excavated the fossils based their estimates of its gargantuan size on the largest of the thigh bones found. About 150 bones from at least seven individual dinosaurs have been found at the site. They include 10 vertebrae (bones of the spine) from the torso, 40 vertebrae from the tail, parts of the neck, and complete legs. Scientists cannot yet say with certainty that the newly discovered sauropod is the largest dinosaur–and, therefore, the largest animal–to ever walk Earth. Fossil skeletons from sauropods are generally incomplete. In addition, sauropod tails, which accounted for much of the dinosaurs’ length, are particularly rare.

Additional World Book articles:

• Prehistoric animal
• Tyrannosaurus Rex: The Tyrant Still Reigns (a Special Report)
• Paleontology (2003) (a Back in Time article)
• Paleontology (2006) (a Back in Time article)
• Paleontology (2008) (a Back in Time article)
• Paleontology (2013) (a Back in Time article)

Dec. 27, 2011

The discovery of the first sauropod fossil ever found in Antarctica has been announced by a team of scientists from Argentina. Sauropods, a common kind of planet-eating dinosaur, hold the record as the largest land animals to inhabit Earth. The fossil, which has been dated to about 70 million years old, is only a single vertebra–too small for scientists to determine the exact species. (Vertebrae are the bones that make up the spine.) But the scientists determined that the bone belonged to a sauropod. Scientists have found only a few dinosaur fossils in Antarctica because of the continent’s harsh conditions making searching difficult, though they believe many kinds of dinosaurs lived there.

Some sauropods may have grown as long as 130 feet (40 meters) and weighed as much as 85 tons (77 metric tons). They are among the most familiar dinosaurs, with long necks and tails. There were many kinds of sauropods, including such well-known species as Brachiosaurus and Apatosaurus. Sauropods fossils had previously been discovered on all other continents.

Supersaurus was one of the largest dinosaurs that ever lived. It measured from 100 to 130 feet (30 to 40 meters) long, stood about 27 feet (8.2 meters) tall at the hips, and may have weighed more than 40 tons (36 metric tons). The animal's slender neck may have stretched as long as 40 feet (12 meters). Its huge, whiplike tail probably extended about 50 feet (15 meters). World Book illustration by John Francis, Bernard Thornton Artists

The newly discovered dinosaur lived during the Cretaceous Period, which lasted from about 145 million to 65 million years ago. During this time, Antarctica was not covered by a thick ice sheet, as it is now. Earth’s climate was much warmer in the Cretaceous Period than it is today. As a result, Antarctica was able to support plant life, which provided food for large dinosaurs. Also, Antarctica was still connected to what are now Australia and South America in a supercontinent called Pangaea. The fossil was discovered on Ross Island, in West Antarctica.

Additional World Book articles:

• Diplodocus
• Plants (Early plants)
• Prehistoric animal
• Seismosaurus
• Supersaurus