Кретарий кезеңінде өмір сүрген саркозух жануарлары

Extinct genus of reptiles

Sarcosuchus (,/s//ɑːr//k//oʊ /'/s//uː//k//ə//s/; ) is an extinct genus of crocodyliform and distant relative of living crocodilians that lived during the Early Cretaceous, from the late Hauterivian to the late Cenomanian, 133 to 93 million years ago of what are now North Africa and South America. The genus name comes from the Greek σάρξ (sarx) meaning flesh and σοῦχος (souchus) meaning crocodile. It was one of the largest pseudosuchians, with the largest specimen of S. imperator reaching approximately long and weighing up to It is known from two species; S. imperator from the early Albian Elrhaz Formation of Niger, and S. hartti from the Late Hauterivian of northeastern Brazil. Other material is known from Morocco and Tunisia and possibly Libya and Mali. The first remains were discovered during several expeditions led by the French paleontologist Albert Félix de Lapparent, spanning from 1946 to 1959, in the Sahara. These remains were fragments of the skull, vertebrae, teeth, and scutes. In 1964, an almost complete skull was found in Niger by the French CEA, but it was not until 1997 and 2000 that most of its anatomy became known to science, when an expedition led by the American paleontologist Paul Sereno discovered six new specimens, including one with about half the skeleton intact and most of the spine.

Sarcosuchus is a distant relative of living crocodilians, with fully grown individuals estimated to have reached up to in total length and in weight. 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 living gharial, but in fully grown individuals it became considerably broader. The largest known skull of S. imperator (the type specimen) is long ( in the midline), and it was estimated that the individual it belonged to had a total body length of and in turn this measurement was used to estimate its body weight at the Late Cretaceous Deinosuchus, and the Miocene Purussaurus 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 largest S. imperator was significantly smaller than was estimated by Sereno et al. (2001) based on modern crocodilians. O’Brien et al. (2019) estimated the length of the largest S. imperator specimen at nearly and body mass at 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 and , respectively. a group of crocodile like reptiles (Crocodyliformes) related but outside Crocodylia (the clade containing living crocodiles, alligators and gharials). Simplified cladogram after Fortier et al. (2011). Later, in 1964, the research team of the French CEA discovered an almost complete skull in the region of Gadoufaoua in the Niger. The said skull was shipped to Paris for study and became the holotype of the then new genus and species Sarcosuchus imperator in 1966. In 1867, American naturalist Charles Hartt found two isolated teeth and sent them to the American paleontologist O. C. Marsh who erected a new species of Crocodylus for them, C. hartti. This material, along with other remains were assigned in 1907 to the genus Goniopholis as G. hartti. Now residing in the British Museum of Natural History, the fragment of the lower jaw, dorsal scute and two teeth compromising the species G. hartti were reexamined and conclusively placed in the genus Sarcosuchus. Fossils were found in 2010 in the Ifezouane Formation of Morocco. Fossil teeth from the area of Nalut in northwestern Libya, possibly Hauterivian to Barremian in age, might be referable to S. imperator. Indeterminate Sarcosuchus 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 the Oum Ed Dhiab Member in Tunisia in 2018.

Sereno took thin sections from trunk osteoderms of an estimated subadult individual (~80% of estimated maximum adult size). Sereno suggested that S. imperator achieved its large size by extending its period of rapid, juvenile, growth.

Based on the broader snout of fully grown S. imperator when compared with the living gharial and other narrow snouted crocodiles, along with a lack of interlocking of the smooth and sturdy crowned teeth when the jaws were closed, Sereno et al. This suggests that if S. imperator did hunt big game, it probably did not dismember prey in the same fashion as extant crocodilians.

The remains of S. imperator were found in a region of the Ténéré Desert named Gadoufaoua, more specifically in the Elrhaz Formation of the Tegama Group, dating from the late Aptian to the early Albian of the Early Cretaceous,

Meanwhile, S. hartti was found in the Recôncavo Basin of Brazil, specifically in the Ilhas Formation of the Bahia series. It was a shallow lacustrine environment dating from the late Aptian, similar in age to the habitat of S. imperator, with similar aquatic fauna, including Lepidotus and two species of Mawsonia. The dinosaur fauna is of a very fragmentary nature and identification does not go beyond indeterminate theropod and iguanodontid remains.