Deinosuchus: Description

Description:

Morphology:

Despite its massive size, the overall physical appearance of Deinosuchus was not considerably different from that of modern crocodilians. Deinosuchus had an alligator-like broad snout, with a slightly bulbous tip. The teeth were thick and robust; those close to the rear of the jaws were short, rounded, and blunt. The osteoderms (scutes) covering the back were unusually large, heavy, and deeply pitted; some were of a roughly semicircular shape

Physiology:

The bite force of Deinosuchus has been estimated to exceed 18,000 newtons. In contrast, modern American alligators, with the strongest bite of any living animal, have been measured no higher than 9,452 newtons.[6] Even the largest and strongest theropod dinosaurs, such as Tyrannosaurus, probably had a bite force weaker than that of Deinosuchus.

Deep pits and grooves on the osteoderms of Deinosuchus served as attachment points for connective tissues. Together, these osteoderms and connective tissues would have served as load-bearing reinforcement to support the massive body of Deinosuchus on land. Consequently, despite its massive bulk, Deinosuchus was probably capable of a "high walk," "belly run," or even a full gallop, just like most modern crocodilians.

Deinosuchus had a secondary bony palate, which would have permitted it to breathe through its nostrils while the rest of the head remained submerged underwater. The vertebrae were articulated in a procoelus manner, meaning that they had a concave hollow on the front end and a convex bulge on the rear; these would have fit together to produce a ball and socket joint. The secondary palate and procoelus vertebrae are advanced features also found in modern eusuchian crocodilians.

Size:

Because the known remains of Deinosuchus are so fragmentary, estimates of its size have varied significantly. In 1954, Edwin H. Colbert and Roland T. Bird reconstructed the lower jaw of Deinosuchus with a length of 2 m (6.6 ft), and calculated "on the basis of comparative measurements" that the giant crocodilian's total body length could have been up to 15 m (50 ft). A much lower estimate — 8 to 10 m (26 to 33 ft) — was given by Gregory M. Erickson and Christopher A. Brochu in 1999. David R. Schwimmer suggested in 2002 that the smaller and more common form of Deinosuchus found in eastern North America usually grew to about 8 m (26 ft) and 2.3 tons. According to Schwimmer's research, Deinosuchus reached larger sizes in the western portion of the continent; he estimates that the biggest specimens had a total body length of up to 12 m (40 ft), and perhaps weighed 8.5 tons or more.

Although there is some disagreement as to its exact size, the fossil remains are nonetheless sufficient to indicate that Deinosuchus was substantially larger than any modern crocodilian. Even the relatively low estimate provided by Erickson and Brochu suggests that the maximum weight reached by Deinosuchus exceeded that of currently living species by a factor of three to five.

Habitat

Deinosuchus specimens have been discovered in freshwater and marine deposits.
Diet

In 1954, Edwin H. Colbert and Roland T. Bird speculated that Deinosuchus "may very well have hunted and devoured some of the dinosaurs with which it was contemporaneous." In 1961, Colbert more confidently restated this hypothesis: "Certainly this crocodile must have been a predator of dinosaurs; otherwise why would it have been so overwhelmingly gigantic? It hunted in the water where the giant theropods could not go." It is generally assumed that Deinosuchus would have employed similar hunting tactics to modern crocodilians, ambushing dinosaurs and other terrestrial animals at the water's edge and then submerging them until they drowned. Several hadrosaurid tail vertebrae found near Big Bend National Park show evidence of Deinosuchus tooth marks, strengthening the hypothesis that Deinosuchus fed on dinosaurs in at least some instances.

Research by David R. Schwimmer and G. Dent Williams indicates that Deinosuchus may have preyed on marine turtles. Deinosuchus would probably have used the robust, flat teeth near the back of its jaws to crush the turtle shells. The "side-necked" sea turtle Bothremys was especially common in the eastern habitat of Deinosuchus, and several of its shells have been found with bite marks that were most likely inflicted by the giant crocodilian.

Growth rates

A 1999 study by Gregory M. Erickson and Christopher A. Brochu suggested that the growth rate of Deinosuchus was comparable to that of modern crocodilians, but was maintained over a far longer period of time. Their estimates, based on growth rings in the dorsal osteoderms of various specimens, indicate that each Deinosuchus might have taken over 35 years to reach full adult size, and that the oldest individuals may have lived for more than 50 years. According to Erickson, a full-grown Deinosuchus "must have seen several generations of dinosaurs come and go."

David R. Schwimmer noted in 2002 that Erickson and Brochu's assumptions about growth rates are only valid if the osteodermal rings reflect annual periods, as they do in modern crocodilians. According to Schwimmer, the growth ring patterns observed in Deinosuchus could have been affected by a variety of factors, including "migrations of their prey, wet-dry seasonal climate variations, or oceanic circulation and nutrient cycles". If the ring cycle was biannual rather than annual, this might indicate that Deinosuchus grew faster than modern crocodilians, and had a similar maximum lifespan

Discovery and classification:

In 1858, geologist Ebenezer Emmons described two large fossil teeth found in Bladen County, North Carolina. Emmons referred these teeth to Polyptychodon, which he then believed to be "a genus of crocodilian reptiles." Later discoveries showed that Polyptychodon was actually a pliosaur. The teeth described by Emmons were thick, slightly curved, and covered with vertically-grooved enamel; he assigned them a new species name, P. rugosus. Although not initially recognized as such, these teeth were probably the first Deinosuchus remains to be scientifically described.

In 1903, at Willow Creek, Montana, several fossil osteoderms were discovered "lying upon the surface of the soil" by John Bell Hatcher and T.W. Stanton.These osteoderms were initially attributed to the ankylosaurid dinosaur Euoplocephalus.[4] Excavation at the site, carried out by W.H. Utterback, yielded further fossils, including additional osteoderms as well as vertebrae, ribs, and a pubis.[4] When these specimens were examined, it became clear that they belonged to a large crocodilian and not a dinosaur; upon learning this, Hatcher "immediately lost interest" in the material. After Hatcher died in 1904, his colleague W.J. Holland studied and described the fossils. Holland assigned these specimens to a new genus and species, Deinosuchus hatcheri, in 1909.
A 1940 expedition by the American Museum of Natural History yielded more fossils of giant crocodilians, this time from Big Bend National Park in Texas. These specimens were described by Edwin H. Colbert and Roland T. Bird in 1954, under the name Phobosuchus riograndensis. Donald Baird and Jack Horner later determined that the genus name Phobosuchus was taxonomically invalid, and that the Big Bend remains described by Colbert and Bird should therefore properly be assigned to Deinosuchus.

The American Museum of Natural History incorporated the skull and jaw fragments into a plaster restoration, modeled after the present-day Cuban crocodile. Colbert and Bird stated that this was a "conservative" reconstruction, since an even greater length could have been obtained if a long-skulled modern species such as the saltwater crocodile had been used as the template. Because it was not then known that Deinosuchus had a broad snout, Colbert and Bird miscalculated the proportions of the skull, and the reconstruction greatly exaggerated its overall width and length.[5]

Despite its inaccuracies, the reconstructed skull became the best-known specimen of Deinosuchus, and brought public attention to this giant crocodilian for the first time.

Specimens have also been found in Alabama, Mississippi, Georgia, New Jersey, North Carolina, Wyoming, New Mexico and recently also in Mexico.

Originally classified in the family Crocodylidae, a better skull specimen shows it is most likely a basal member of Alligatoroidea.

Scientific classification:

Scientific classification:

Kingdom: - Animalia
Phylum: - Chordata
Class: - Sauropsida
Order: - Crocodilia
Suborder: - Eusuchia
Superfamily: - Alligatoroidea
Genus: - Deinosuchus

Deinosuchus:

Deinosuchus is an extinct genus of alligatoroid that lived 80 to 73 million years ago, in the Late Cretaceous period. The name Deinosuchus means "terrible crocodile" and is derived from the Greek δεινός/deinos ("terrible") and σουχος/suchos ("crocodile"). A top predator in the coastal regions of eastern North America, Deinosuchus was capable of killing and eating large dinosaurs.

Thought for several decades to be the largest crocodilian that ever existed, Deinosuchus is known mainly from skull material. Recent studies have reduced its estimated length. Some other giant crocodilians, including Sarcosuchus (the "SuperCroc"), Purussaurus and Rhamphosuchus, were as big or bigger, but accurate comparisons are difficult as Sarcosuchus is the only species known from a largely-complete skeleton.

Liopleurodon - Description

Liopleurodon:

Palaeobiology

Four strong paddle-like limbs suggest that Liopleurodon was a powerful swimmer. Its four-flipper mode of propulsion is characteristic of all plesiosaurs. A study involving a swimming robot has demonstrated that although this form of propulsion is not especially efficient, it provides very good acceleration - a desirable character in an ambush predator. Studies of the skull have shown that it could probably scan the water with its nostrils to ascertain the source of certain smells.

Size issue:

Estimating the maximum size of Liopleurodon has become a controversial subject. The paleontologist L. B. Tarlo derived that the total body length of a pliosaur (including Liopleurodon) can be estimated from skull length, in which the skull is approximately one seventh of the entire body. The largest known skull belongs to L. ferox (1.5 meters in length), and according to Tarlo's estimation, this individual would be about 11 m (38 ft) long. However, as with its relative Kronosaurus, there is some uncertainty as to whether Tarlo's estimations are correct.

Recent studies on pliosaurs have cast doubt on Tarlo's estimations, and indicate that pliosaur skulls were about one-fifth of the total body length. Hence, the average size of the L. ferox would have ranged from 7 meters (23 ft) to 10 meters (33 ft) long.

The size estimate of Liopleurodon from the 1999 BBC series Walking with Dinosaurs, which depicts an enormous 25 meter-long Liopleurodon, is not considered to be accurate for any species of Liopleurodon.

Pliosaur remains excavated from Kimmeridge Clay Formatio n of England indicate a much larger taxon, possibly up to 15 meters (49.2 feet long), existed, however they have not been identified as being to Liopleurodon. A mandible on display in the Oxford University Museum of Natural History estimated over 3 meters (preserved 2.875m) was at one time classified as Liopleurodon macromerus. When the mandible was described, it was originally assigned to Stretosaurus (as Stretosaurus macromerus). The genus Stretosaurus later became a junior synonym of Liopleurodon. However, it has been re-classified as Pliosaurus macromerus.

The discovery of a very large pliosaur was announced in 2002, from Mexico, nicknamed the 'Monster of Aramberri'. A cautious estimate placed this juvenile at a bout 15 meters (49.2 ft) long. It was widely reported belonging to Liopleurodon, however no taxonomic conclusions could be made due to poor preservation and fact that the remains were of a partial vertebral column (non-diagnostic). The specimen was dated to the Kimmeridgian age of the La Caja Formation.

In popular culture

In 1999, Liopleurodon was featured in an episode the BBC television series Walking with Dinosaurs. In the program, Liopleurodon was depicted attacking and devouring the theropod dinosaur Eustreptospondylus, before becoming beached during a typhoon and suffocating under its own weight. Two adult Eustreptospondylus who survived the storm feed u pon it. The depiction of Liopleurodon leaping onto the land in order to catch land-based prey is entirely speculative, although the program's producers state that the behavior was inspired by that of orcas.

According to a 2008 article written for About.com, the popularity of Liopleurodon, which had previously been more obscure in popular culture than other well-known pliosaurs such as Kronosaurus, experienced an upsurge following its mention in the online animated short Charlie the Unicorn.

Liopleurodon:

Liopleurodon - is a genus of large, carnivorous marine reptile belonging to the Pliosauroidea, a clade of the short-necked plesiosaurs. Two species of Liopleurodon lived during the Callovian stage of the Middle Jurassic Period (c. 160 million to 155 million years ago mya), while the third, L. rossicus, lived during the Late Jurassic. It was the apex predator of the Middle to Late Jurassic seas that covered Europe.

Discovery and species:

The genus name Liopleurodon was coined by H.E Sauvage in 1873 on the basis of very poor remains consisting of three large, 70 mm, teeth. One tooth was found near Boulogne-sur-Mer, France in layers dating from the Callovian was named Liopleurodon ferox, another from Charly, France was named Liopleurodon grossouvrei, while a third discovered near Caen, France was originally described as Poikilopleuron bucklandi and ascribed by Sauvage to the species Liopleurodon bucklandi). Sauvage did not ascribe the genus to any particular group of reptiles in his descriptions.

Liopleurodon fossils have been found mainly in England and France, with one younger species known from Russia. Fossil specimens that are contemporary (Callovian) with those from England and France referrable to Liopleurodon are known from Germany.

Currently, there are three recognized species within Liopleurodon. From the Callovian of England and France L. ferox is well known; while also from the Callovian of England is the rarer L. pachydeirus, described by Seeley as a Pliosaurus (1869). From the Volgian of Russia, L. rossicus is known. This species was initially described by Novozhilov (1948) as belonging to Pliosaurus, and is the type species of the genus Strongylokroptaphus. Only L. ferox is known from more or less complete skeletons.