Suchomimus is a genus of large theropod dinosaur that lived in what is now Niger during the Aptian to Albian stages of the Early Cretaceous period, 112 million years ago. The only known species is S. tenerensis, originally described in 1998 by paleontologist Paul Sereno and colleagues from several fossils discovered one year earlier in the Elrhaz Formation. Although these fossils come from multiple specimens, they represent one of the most anatomically well-documented spinosaurids. The animal's generic name, which means "crocodile mimic", alludes to its elongated skull and piscivorous adaptations, while the specific name refers to the Ténéré Desert, where the fossils were discovered. With an estimated length of 9.5–11 metres (31–36 ft) and a body mass ranging from 2.5–3.8 metric tons (2.8–4.2 short tons), Suchomimus was a particularly large theropod. As its generic name suggests, the animal’s skull was elongated, low, and narrow, resembling that of crocodilians. The tip of the snout flared laterally to form a rosette, and the jaws bore numerous finely serrated conical teeth, with the largest ones positioned near the front. The neck of Suchomimus was relatively short, while its powerfully built forelimbs bore a large, curved claw on each thumb. Along the midline of the animal's back ran a low dorsal sail, built from the long neural spines of its vertebrae. Its cranial and limb features indicate that it was a primarily piscivorous predator adapted for hunting in shallow waters. Some paleontologists consider Suchomimus to be a junior synonym of the contemporaneous spinosaurid Cristatusaurus, although the latter taxon is based on fragmentary remains. Yet more have also suggested that Suchomimus might represent an African species of the European spinosaurid Baryonyx, and it has occasionally been referred to in the scientific literature as B. tenerensis. However, more recent studies continue to regard the two genera as distinct. According to the fossil record of the Elrhaz Formation, Suchomimus lived and hunted in a fluvial environment of vast floodplains alongside many other dinosaurs, in addition to pterosaurs, crocodylomorphs, bony fishes, turtles, and bivalves.
History of study
Discovery and naming
In late 1997, American paleontologist Paul Sereno and his team conducted an expedition at the Gadoufaoua site in the Ténéré Desert of Niger, where they uncovered various fossils. On 4 December, team member David Varricchio discovered a large thumb claw belonging to a massive theropod dinosaur, remarkably well exposed on the surface. According to Sereno, the sand and wind had gradually revealed this claw, which had remained visible in this state for at least two centuries. Subsequent excavations at the site recovered several fossils from different individuals of this enigmatic theropod, which proved to belong to the spinosaurid family. On 13 November 1998, the Science Magazine published a study led by Sereno, formally naming and describing the new genus and species Suchomimus tenerensis based on the fossils discovered during the expedition. The generic name Suchomimus derives from the Ancient Greek σοῦχος (souchos, "crocodile"), and μῖμος (mimos, "mimic") literally meaning "crocodile mimic", in reference to its elongated snout and piscivorous adaptations. The specific name tenerensis refers to the desert where the animal’s fossils were found.
All known fossil specimens were recovered from the Elrhaz Formation and are now housed in the paleontological collections of the Musée National Boubou Hama in Niamey. The holotype, catalogued as MNN GDF500, consists of a partial skeleton lacking the skull. It contains three neck ribs, parts of fourteen dorsal (back) vertebrae, ten dorsal ribs, gastralia (or "belly ribs"), pieces of three sacral vertebrae, parts of twelve caudal (tail) vertebrae, chevrons (bones that form the underside of the tail), a scapula (shoulder blade), a coracoid, a partial forelimb, most of the pelvis (hip bone), and parts of a hindlimb. Other notable specimens are also mentioned in the paper describing the taxon. Specimens MNN GDF 501 to 508 include a snout, a quadrate from the back of the skull, three dentaries (tooth-bearing bones of the lower jaw), an axis (second neck vertebra), a rear cervical vertebra, and a rear dorsal vertebra. Specimens MNN GDF510 and 511 consist of two caudal vertebrae. In the same article, Sereno and colleagues also reported additional bones and teeth attributed to this dinosaur, though their catalogue numbers were not specified. Although Suchomimus is among the best-known spinosaurids anatomically, its original description remains relatively brief.
Suggested synonymy with Baryonyx and Cristatusaurus
More than two months before S. tenerensis was formally described in the scientific literature, French paleontologist Philippe Taquet and his Canadian colleague Dale A. Russell named another spinosaurid from the Elrhaz Formation, Cristatusaurus lapparenti, based on fragments of jaws and vertebrae. The fossils of this taxon were first discovered in 1973 by Taquet at Gadoufaoua, who later reported the find and described the fossil premaxillae in a paper published in 1984. Although he did not assign them a scientific name at the time, the author recognized the fossils as belonging to a large theropod of the Spinosauridae family based on anatomical features shared with the now-destroyed holotype of Spinosaurus aegyptiacus. In a 1986 publication, British paleontologists Alan Charig and Angela Milner noted that the jaw elements described by Taquet were nearly indistinguishable from those of Baryonyx walkeri, which they had just described from a partial skeleton dating to the Barremian stage of the Weald Clay Formation in England. In a 1997 follow-up to their preliminary paper, the same authors referred Taquet’s fossils to an indeterminate species of Baryonyx, despite their younger geological age. In their 1998 paper, Sereno and colleagues agreed with Charig and Milner that there were no significant differences between the fossil skulls of Baryonyx and Cristatusaurus, concluding that the latter should be regarded as a nomen dubium.
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