Sarcosuchus (/ˌsɑːrkoʊˈsuːkəs/), fromAncient Greek σάρξ (sárx), meaning "flesh", and σούχος (soúkhos), meaning "crocodile", is anextinctgenus ofcrocodyliform and distant relative of livingcrocodilians that lived during theEarly Cretaceous, from the lateHauterivian to the earlyAlbian stages, 130 to 112 million years ago of what is nowAfrica andSouth America. It was one of the largestpseudosuchians, with the largest specimen ofS. imperator reaching approximately 9–9.5 metres (29.5–31.2 ft) long and weighing up to 3.45–4.3 metric tons (3.80–4.74 short tons). It is known from two species;S. imperator from the early AlbianElrhaz Formation ofNiger, andS. hartti from the Late Hauterivian of northeasternBrazil. Other material is known fromMorocco andTunisia and possiblyLibya andMali.

Sarcosuchus Temporal range:Late Hauterivian-Early Albian ~130–112 Ma PreꞒ Ꞓ O S D C P T J K Pg N PossibleCenomanian record[1]
S. imperator,Muséum national d'histoire naturelle, Paris
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauria
Clade:	Pseudosuchia
Clade:	Crocodylomorpha
Family:	†Pholidosauridae
Genus:	†Sarcosuchus Broin & Taquet, 1966
Type species
†Sarcosuchus imperator Broin & Taquet, 1966
Other species
†S. hartti (Marsh, 1869) (originallyCrocodylus)

The first remains were discovered during several expeditions led by the FrenchpaleontologistAlbert-Félix de Lapparent, spanning from 1946 to 1959, in theSahara. These remains were fragments of theskull,vertebrae,teeth, andscutes. In 1964, an almost complete skull was found inNiger by the FrenchCEA, but it was not until 1997 and 2000 that most of its anatomy became known to science, when an expedition led by the AmericanpaleontologistPaul Sereno discovered six new specimens, including one with about half theskeleton intact including most of thespine.

Sarcosuchus is a distant relative ofliving crocodilians, with fully grown individuals estimated to have reached up to 9 to 9.5 m (29.5 to 31.2 ft) in total length and 3.45 to 4.3 metric tons (3.80 to 4.74 short tons) in weight.^[2] It had somewhat telescoped eyes and a long snout comprising 75% of the length of the skull. There were 35 teeth in each side of the upper jaw, while in the lower jaw there were 31 teeth in each side. The upper jaw was also noticeably longer than the lower one, leaving a gap between them when the jaws were shut that created an overbite. In young individuals the shape of the snout resembled that of the livinggharial, but in fully grown individuals it became considerably broader.^[3][4]

Sarcosuchus has an expansion at the end of its snout known as a bulla, which has been compared with the ghara seen ingharials. However, unlike the ghara, which is only found in male gharials, the bulla is present in allSarcosuchus skulls that have been found so far, suggesting that it was not asexually dimorphic trait. The purpose of this structure is not known.

Theosteoderms, also known as dermalscutes, ofSarcosuchus were similar to those goniopholodids likeSunosuchus andGoniopholis; they formed an uninterrupted surface that started in the posterior part of the neck down to the middle of the tail as is seen inAraripesuchus and other basal crocodyliforms; this differs from the pattern seen in living crocodiles, which presents discontinuity between the osteoderms of the neck and body.^[3]

A common method to estimate the size of crocodiles and crocodile-like reptiles is the use of the length of the skull measured in the midline from the tip of the snout to the back of the skull table,^[3] as in living crocodilians there is a strong correlation between skull length and total body length in subadult and adult individuals irrespective of their sex.^[5] This method was used by Serenoet al. (2001) forSarcosuchus due to the absence of a complete enough skeleton. Two regression equations were used to estimate the size ofS. imperator, they were created based on measurements gathered from 17 captivegharial individuals from northernIndia and from 28 wildsaltwater crocodile individuals from northernAustralia,^[3] both datasets supplemented by available measurements of individuals over 1.5 m (4.92 ft) in length found in the literature.^[3][6] The largest known skull ofS. imperator (the type specimen) is 1.6 m (5.25 ft) long (1.5 m (4.92 ft) in the midline), and it was estimated that the individual it belonged to had a total body length of 11.65 m (38.2 ft).^[3] Its snout-vent length of 5.7 m (18.7 ft) was estimated using linear equations for the saltwater crocodile^[7] and in turn this measurement was used to estimate its body weight at 8 metric tons (8.8 short tons).^[3] This shows thatSarcosuchus was able to reach a maximum body size not only greater than previously estimated^[3] but also greater than that of theMioceneRhamphosuchus,^[8] theLate CretaceousDeinosuchus,^[9][10] and theMiocenePurussaurus^[11] according to current estimates at that time.

However, extrapolation from the femur of a subadult individual as well as measurements of the skull width further showed that the largestS. imperator was significantly smaller than was estimated by Serenoet al. (2001) based on modern crocodilians. O’Brienet al. (2019) estimated the length of the largestS. imperator specimen at nearly 9 metres (29.5 ft) and body mass at 3.45 metric tons (3.80 short tons) based on longirostrine crocodylian skull width to total length and body width ratio. The highest upper quartile reconstructed length and body mass for the specimen is 9.5 metres (31.2 ft) and 4.3 metric tons (4.7 short tons), respectively.^[2]

Sarcosuchus is commonly classified as part of the cladePholidosauridae,^[3][12][13] a group of crocodile-like reptiles (Crocodyliformes) related but outsideCrocodylia (the clade containing living crocodiles, alligators and gharials).^[3] Within this group it is most closely related to theNorth American genusTerminonaris.^[3] Most members of Pholidosauridae had long, slender snouts and they all were aquatic, inhabiting several different environments. Some forms are interpreted as marine, capable of toleratingsaltwater while others, likeSarcosuchus, werefreshwater forms. The most primitive members of the clade, however, were found in coastal settings, zones mixing freshwater and marine waters.^[13]Sarcosuchus stands out among pholidosaurids for being considered a generalist predator, different from most known members of the clade which were specialized piscivores.^[3] A 2019 study found it to be in a more derived position inTethysuchia, being phylogenetically closer toDyrosauridae.^[14]

Simplified cladogram after Fortieret al. (2011).^[13]

During the course of several expeditions on the Sahara from 1946 to 1959 which were led by the French paleontologistAlbert-Félix de Lapparent, several fossils of a crocodyliform of large size were unearthed in the region known as theContinental Intercalaire Formation. Some of them were found in Foggara Ben Draou, inMali and near the town ofAoulef,Algeria (informally named as the Aoulef Crocodile) while others came from theAin el Guettar Formation of Gara Kamboute. In the south ofTunisia, the fossils found were fragments of the skull, teeth,scutes and vertebrae. In 1957, in the region now known as theElrhaz Formation, several isolated teeth of great size were found by H. Faure. The study of this material by French paleontologist France De Broin helped identify them as coming from a long-snouted crocodile.^[12]

Later, in 1964, the research team of the FrenchCEA discovered an almost complete skull in the region ofGadoufaoua in the Niger. The said skull was shipped toParis for study and became the holotype of the then new genus and speciesSarcosuchus imperator in 1966.^[12]

In 1977, a new species ofSarcosuchus was recognised,S. hartti, from remains found in the late 19th century in lateHauterivian pebbly conglomerates and green shales belonging to theIlhas Formation in the Recôncavo Basin of north-easternBrazil.^[4] In 1867, AmericannaturalistCharles Hartt found two isolated teeth and sent them to the American paleontologistO. C. Marsh who erected a new species ofCrocodylus for them,C. hartti.^[15] This material, along with other remains were assigned in 1907 to the genusGoniopholis asG. hartti.^[16] Now residing in theBritish Museum of Natural History, the fragment of the lower jaw, dorsal scute and two teeth compromising the speciesG. hartti were reexamined and conclusively placed in the genusSarcosuchus.^[4]

The next major findings occurred during the expeditions led by the American paleontologistPaul Sereno in 1995 (Aoufous Formation,Morocco), 1997 and the follow-up trip in 2000. Partial skeletons, numerous skulls and 20 tons of assorted other fossils were recovered from the deposits of theElrhaz Formation, which has been dated as lateAptian or earlyAlbianstages of the Late Cretaceous. It took about a year to prepare theSarcosuchus remains.^[3][17]

A tooth enamel from the Ifezouane Formation (lowerKem Kem beds) of Morocco was identified ascf.Sarcosuchus.^[1] Fossil teeth from the area ofNalut in northwesternLibya, possiblyHauterivian toBarremian in age, might be referable toS. imperator.^[18] IndeterminateSarcosuchus material including dorsal osteoderms in anatomical connection, isolated teeth and fragmentary skeletal remains including a left scapula, mandible fragment, dorsal vertebrae, ilium and a proximal portion of a femur was described from theOum Ed Dhiab Member in Tunisia in 2018.^[19]

Sereno took thin sections from trunk osteoderms of an estimated subadult individual (~80% of estimated maximum adult size).^[3] Approximately 40lines of arrested growth (LAG) were counted in these thin sections, suggesting thatS. imperator took 50 to 60 years to reach adult size.^[3] Given thatextant wild crocodylians rarely reach these advanced ages,^[5][20] Sereno suggested thatS. imperator achieved its large size by extending its period of rapid, juvenile, growth.^[3] A similar growth strategy has been suggested for the equally titanic crocodylianDeinosuchus, based on similar criteria.^[9]

Based on the broader snout of fully grownS. imperatorwhen compared with the livinggharial and other narrow-snouted crocodiles, along with a lack of interlocking of the smooth and sturdy-crowned teeth when the jaws were closed, Serenoet al.^[3] hypothesized thatS. imperator had a generalized diet similar to that of theNile crocodile, which would have included large terrestrial prey such as the abundant dinosaurs that lived in the same region.^[3]

However, a 2014 analysis of a biomechanical model of its skull suggested that unlikeDeinosuchus,Sarcosuchus may not have been able to perform the "death roll" maneuver used by extant crocodilians to dismember their prey.^[21][22] This suggests that ifS. imperator did hunt big game, it probably did not dismember prey in the same fashion as extant crocodilians.

The remains ofS. imperator were found in a region of theTénéré Desert named Gadoufaoua, more specifically in theElrhaz Formation of the Tegama Group, dating from the lateAptian to the earlyAlbian of theEarly Cretaceous,^[23] approximately 112 million years ago.^[3] The stratigraphy of the region and the aquatic fauna that was found therein indicates that it was an inland fluvial environment, entirely freshwater in nature with a humid tropical climate.^[3][12][23]S. imperator shared the waters with theholostean fishLepidotus and the coelacanthMawsonia.^[4] The dinosaur fauna was represented by the iguanodontianLurdusaurus, which was the most common dinosaur in the region, and its relativeOuranosaurus; there were also two sauropods,Nigersaurus and a currently unnamed sauropod while the theropod fauna included the spinosauridSuchomimus, the carcharodontosauridEocarcharia and the abelisauridKryptops.^[23][24]

Meanwhile,S. hartti was found in the Recôncavo Basin ofBrazil, specifically in the Ilhas Formation of the Bahia series. It was a shallowlacustrine environment dating from the late Aptian, similar in age to the habitat ofS. imperator, with similar aquatic fauna, includingLepidotus and two species ofMawsonia. The dinosaur fauna is of a very fragmentary nature and identification does not go beyond indeterminate theropod and iguanodontid remains.^[4]

• Sloan, C. (2002).SuperCroc and the Origin of Crocodiles. National Geographic.ISBN 978-0-7922-6691-4.

• "African fossil find: 40-foot crocodile". Guy Gugliotta.Washington Post, October 26, 2001. Retrieved November 17, 2004.
• SuperCroc: Sarcosuchus imperatorArchived March 19, 2016, at theWayback Machine. Gabrielle Lyon. Retrieved November 17, 2004.
• "'SuperCroc' fossil found in Sahara". D. L. Parsell.National Geographic News, October 25, 2001. Retrieved November 17, 2004.
• Dinosaur Expedition 2000Archived December 12, 2004, at theWayback Machine. Paul C. Sereno. Retrieved November 17, 2004.
• "SuperCroc's jaws were superstrong, study shows". John Roach.National Geographic News, April 4, 2003. Retrieved November 17, 2004.
• "Sereno, team discover prehistoric giant Sarcosuchus imperator in African desert." Steve Koppes.The University of Chicago Chronicle, volume 21, number 4, November 1, 2001. Retrieved November 17, 2004.
• Making of theSarcosuchus exhibitArchived March 3, 2016, at theWayback Machine