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Sarcosuchus

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The Land Before Time species
Ms Sarcosuchus
Sarcosuchus
Fossil range Early Cretaceous period
Kingdom Animalia
Phylum Chordata
Class Reptilia
Superorder Crocodylomorpha
Order
Family Pholidosauridae
Subfamily
Genus Sarcosuchus (Broin and Taquet, 1966)
Species S. imperator Broin & Taquet, 1966 (type)
S. hartii (Marsh, 1869 (originally Crocodylus))
Synonyms
TLBT characters of this species Belly Dragger (Great Longneck Migration)
Miscellaneous

Sarcosuchus was a giant crocodilian and was a close relative to Deinosuchus . It was much larger than a modern crocodile, ranging around 8 tons. The fossils have been found around in Africa & lived during the Early Cretaceous era.

Description

Sarcosuchus was one of the largest giant crocodile-like reptiles that ever lived. It was almost twice as long as the modern saltwater crocodile and weighed about 8 to 10 metric tons.[1]

Its skull was as big as a human (1.78 m, or 5 ft 10 inches). The upper jaw overlapped the lower jaw, making an overbite. The jaws were quite slim (especially in juveniles). The snout is made up of about 75% of the skull's length.[2] The teeth were cone-shaped, built to grab and hold, like those of true crocodilians, which, most of the time, kill prey by holding them underwater until they drown.[3]

Sarcosuchus had a strange dent at the end of its snout. Called a bulla, it has been compared to the ghara seen in gharials. Unlike the ghara, though, the bulla is seen in all Sarcosuchus skulls that have been found so far, while just the male gharial has a ghara. The use of this structure is still not clear. Sereno and others asked various reptile researchers what their thoughts on this bulla were. Views ranged from it boosting their sense of smell to being connected to a vocalization device.[4]

Classification

Sarcosuchus is not an ancestor of modern crocodiles, nor is it a crocodilian in the phylogenetic definition of the term. A crocodilian is any member of the clade Crocodilia. Crocodilia includes all modern forms, such as crocodiles proper, alligators, etc., and their immediate prehistoric relatives. Sarcosuchus is a member of the family Pholidosauridae, more distantly related to today's crocodilians.

"Crocodile" is a term often used in a broad sense. The first "crocodile-like reptiles" — the Crocodylomorpha — which split from the bird-line of archosaurs — the group of reptiles that include dinosaurs, pterosaurs and birds — about 230 million years ago, in the Late Triassic, looked somewhat like modern crocodilians. They had long legs and long bodies covered with armour.

Until the 1980s, the pholidosaurids were classified as part of the presumed suborder Mesosuchia, within the order Crocodilia. However, Benton and Clark determined in 1988 that Mesosuchia was a parphyletic group, containing the ancestor of all modern crocodiles. A simplified evolutionary tree:[5]

Teeth and osteoderms found in Brazil come from a close relative of Sarcosuchus: Sarcosuchus hartii (Marsh, 1869). S. hartii has a complicated taxonomic history. It was discovered in 1867 by an American naturalist, Hartt near a train station in the area of Recôncavo in the state of Bahia in northeastern Brazil. Hartt send the fossils - teeth, osteoderms and a fragment of the jaw - to the American paleontologist Othniel Charles Marsh, who later published its scientific description in the American Journal of Science, in 1869, naming based on these remains two new species: Thoracosaurus bahiensis, with small teeth strongly striated and Crocodilus hartii, with large teeth with little roughs.[6] Subsequent findings of crocodilians in the area were attributed to a species described by Edward D. Cope, Hyposaurus derbianus of Pernambuco;[7] in 1907 Mawson and Woodward reclassified the material as belonging to the genus Goniopholis, with the species G. bahiensis and G. hartii, the latter including additional remains found until that time.[8]

The status of these fossils remained so until a restudy of the same made by Eric Buffetaut and Philippe Taquet in 1977. The study examined the remains compared with the genus Sarcosuchus described by Taquet in 1966. The remains showed more similarities to Sarcosuchus than Goniopholis, for example the Brazilian and North African remains had a very long mandibular symphysis, an indicator of long-snouted skull, while Goniopholis had a shorter snout, and therefore its symphysis was equally short. The jaws of both crocodilians were spatulate in form at the front, with the first and second socket of the teeth very small and the third and fourth enlarged teeth are similar in size and shape, with the same enamel ornamentation in the form of roughness winding. The attribution to Goniopholis, based on the shape of the bone scutes, it seems unlikely since it is based on the presence of a peg in them, which is common to other Mesozoic crocodilians as Steneosaurus. Other remains of Bahia attributed to Thoracosaurus bahiensis and Hyposaurus and can not be attributed to the level of genus or species, and their assignment was based on the idea that sediments in the area are Late Cretaceous, when in fact are from the Early Cretaceous. Taquet and Buffetaut therefore concluded that the species should be reassigned to Sarcosuchus, maintaining the separation of African and South American remains in two different species (S. imperator and S. hartii) given the geographical separation, but their level of similarity is so strong that they could not rule that in reality they were a single species, although this hypothesis could only be contrasted with the discovery of additional remains. The Brazilian Sarcosuchus, like S. imperator was a large animal. The skull of S. imperator is 1.8 meters long, with a body of 11 to 12 meters long; for its part, the cranial remains of S. hartii measures 43 centimeters in length, although only is the anterior part of the mandible, so it can be assumed similar in size to the African species. The similarities between this two species it is possibly evidence that land bridges between Africa and South America existed much later than was previously believed.[9]

On the other hand, based on the structure of the snout, the closest relative of Sarcosuchus is the pholidosaurid Terminonaris, with Dyrosaurus and Pholidosaurus as slightly more distant relatives. As a group, they are narrow-snouted fish-eaters from saltwater environments, except for the broader snouted, river-dwelling Sarcosuchus.

History

Until recently, all that was known of it was a few fossilized teeth and armour scutes, which were discovered in the Sahara Desert in the 1940s or 1950s.

In 1997 and 2000, Paul Sereno discovered half a dozen new specimens, including one with about half the skeleton intact and most of the spine. All of the other giant crocodiles are known only from a few partial skulls, so which is actually the biggest is an open question.

Paleobiology

It seems likely that it ate the large fish and turtles of the Cretaceous. As the overhanging jaw and stout teeth are designed for grabbing and crushing, its primary prey may have been large animals and smaller dinosaurs, which it ambushed, dragged into the water, crushed, drowned and then tore apart. The long, thin snout of Sarcosuchus was much like the thin snouts of the modern gharial, the false gharial and the slender-snouted crocodile, all of which, for the most part, just eat fish and can't take on large prey. This can be contrasted to both the modern Nile crocodile and the extinct Deinosuchus, both of which have broad, heavy skulls, that can deal with large prey. This, and the mass of large, lobed-finned fish in its environment, leads most to think that, far from being a dinosaur killer, Sarcosuchus was simply a large piscivore, a scaled-up version of the modern gharial.

Environment

110 million years ago, in the early Cretaceous, the Sahara was still a great tropical plain, dotted with lakes and crossed by rivers and streams that were lined with vegetation. Based on the number of fossils discovered, the aquatic Sarcosuchus was probably plentiful in these warm, shallow, freshwater habitats.

Unlike modern true crocodiles, which are very similar in size and shape to one another and tend to live in different areas; Sarcosuchus was just one of many Crocodyliformes, of different sizes and shapes, all living in the same area.[10] Four other species of extinct Crocodyliformes were also discovered in the same rock formation along with the Sarcosuchus, including a dwarf crocodile with a tiny, 8 cm (3 in) long skull.[10] They filled a diverse variety of ecological niches, instead of competing with each other for resources.

Sarcosuchus in The Land Before Time

In LBT they are called Belly Draggers. One lived in the swamp and appeared twice in the The Land Before Time X: The Great Longneck Migration.

The first time it appears disguises itself as a stone and Littlefoot tried to jump on it. It tried to bite him but was trodden on by Sue. Later it attacks his friends as they pass through. It almost eats Petrie but Cera accidentally makes a log land on it. (it wasn't really red - it's an effect used several times in LBT but never before this drastically, only the sky) Five more appear in The Amazing Threehorn Girl. They come into the Great Valley through a hole in the Great Wall. Two chase the gang. They go after Cera when she goes the other way from the rest but are scared away when she knocks down some rocks by accident. The characters believe they have left the valley and the adults seal the opening - but ominously there is no sign of the crocodilians, the reason being that they have not left the valley.

For rescuing her friends Cera is thought to be a hero and although reluctant at first she begins to exaggerate the story a little bit more each retelling. To prove to Chomper that Cera is lying Littlefoot and Petrie take him to the sight were the Sarcosuchus cornered Cera. However they end up seeing a huge Sarcosuchus and two smaller ones heading towards the middle of the valley. When this is revealed and it turns out Cera was lying the adults try to chase her out of the valley. She runs away and is attacked by all five Belly Draggers. Her father arrives and fights them off, and they are chased from the valley for real since he push this crocodilian down on the ground, bites his tail, and swings it round and round and throws it in the air which makes them scared, threatened and forced to flee immediately. And it land on top of this brown one when its right behind the others.

In Meet Sue from The Land Before Time (2003 edition) from Adventures of The land before time the Sarcosuchus is known as a Swimming Sharp Tooth instead of a Belly Dragger.

External links

References

  1. Lyon, Gabrielle. "Fact Sheet". SuperCroc. Project Exploration. Retrieved 2007-09-22.
  2. Sereno et al., 2001
  3. Dr. Greg M. Erickson, Florida State University Greg Erickson, Faculty page
  4. Geology News, 2001
  5. Sereno, 1998
  6. Marsh, O.C. 1869. Notice of some new reptilian remains from the Cretaceous of Brazil. American Journal of Science 47(141):390-392. The specific name hartii honors Charles Hartt.
  7. Cope, Edward D. 1886. A contribution to the vertebrate paleontology of Brazil. Proceedings of the American Philosophical Society, 23(121):1-21
  8. Mawson, Joseph & Woodward, Arthur Smith, 1907. On the Cretaceous Formation of Bahia (Brazil), and on Vertebrate Fossils collected therein. Quarterly Journal of the Geological Society 63: 128-139
  9. Buffetaut, E., & P. Taquet. 1977. The giant crocodilian Sarcosuchus in the early Cretaceous of Brazil and Niger. Palaeontology 20(1):203-208.PDF
  10. 10.0 10.1 National Geographic Special on SuperCroc. National Geographic Channel, December, 2001.

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