Suchomimus, fromAncient Greek σούχος (soúkhos), meaning "crocodile", and 'mimus', meaning "actor" inLatin, is agenus ofspinosaurid dinosaur that lived between 125 and 112 million years ago in what is nowNiger,North Africa, during theAptian to earlyAlbianstages of theEarly CretaceousPeriod. It was named and described bypaleontologistPaul Sereno and colleagues in 1998, based on a partial skeleton from theElrhaz Formation.Suchomimus' long and shallow skull, similar to that of a crocodile, earns it its generic name, while the specific nameSuchomimus tenerensis alludes to the locality of its first remains, theTénéré Desert.

Suchomimus Temporal range:Early Cretaceous (Barremian toAlbian),125–112 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Reconstructed skeleton at theChicago Children's Museum
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Family:	†Spinosauridae
Clade:	†Ceratosuchopsini
Genus:	†Suchomimus Serenoet al., 1998
Type species
†Suchomimus tenerensis Serenoet al., 1998
Synonyms
Baryonyx tenerensis(Serenoet al., 1998) Sueset al., 2002 [originallySuchomimus]

Suchomimus was a relatively largetheropod, reaching 9.5–11 metres (31–36 ft) in length and weighing 2.5–3.8 metric tons (2.8–4.2 short tons). However, the age of theholotype specimen is uncertain, so it is unclear whether this size estimate would have been its maximum. The narrow head ofSuchomimus was perched on a short neck, and its forelimbs were powerfully built, bearing a giant claw on each thumb. Along the midline of the animal's back ran a lowdorsal sail, built from the longneural spines of itsvertebrae. Like other spinosaurids, it likely had a diet of fish, such as eels, rays, and smaller aquatic animals.

Some palaeontologists consider the genus to be an African species of the European spinosauridBaryonyx,B. tenerensis.Suchomimus might also be ajunior synonym of the contemporaneous spinosauridCristatusaurus lapparenti, although the lattertaxon is based on much more fragmentary remains.Suchomimus lived in afluvial environment of vastfloodplains alongside many other dinosaurs, in addition topterosaurs,crocodylomorphs,bony fishes,testudines, andbivalves.

In 1997, AmericanpalaeontologistPaul Sereno and his team atGadoufaoua discoveredFossils that represented about two-thirds of a largetheropod dinosaur skeleton inNiger. The first find, a giant thumb claw, was made on 4 December 1997 by David Varricchio. In 1998, Sereno, Allison Beck, Didier Dutheil, Boubacar Gado, Hans Larsson, Gabrielle Lyon, Jonathan Marcot, Oliver Rauhut, Rudyard Sadleir,Christian Sidor, David Varricchio, Gregory Wilson, and Jeffrey Wilson named and described thetype speciesSuchomimus tenerensis. The generic nameSuchomimus ("crocodile mimic") is derived from theAncient Greek σοῦχος,souchos, "crocodile", and μῖμος,mimos, "mimic", after the shape of the animal's head. Thespecific nametenerensis is after theTénéré Desert, where the animal was found.^[1]

Theholotype, MNN GDF500, was found in theTegama Beds of theElrhaz Formation. It consists of a partial skeleton, lacking the skull. It contains threeneck ribs, parts of fourteendorsal (back)vertebrae, tendorsal ribs,gastralia (or "belly ribs"), pieces of threesacral vertebrae, parts of twelvecaudal (tail) vertebrae,chevrons (bones that form the underside of the tail), ascapula (shoulder blade), acoracoid, a partial forelimb, most of thepelvis (hip bone), and parts of a hindlimb. Thespinal column was largelyarticulated; the remainder consisted of disarticulated bones. Parts of the skeleton had been exposed on the desert surface and had sufferederosion damage. Additionally, several specimens have been assigned asparatypes: MNN GDF 501 to 508 include asnout, aquadrate from the back of the skull, threedentaries (tooth-bearing bones of the lower jaw), anaxis (second neck vertebra), a rear cervical vertebra, and a rear dorsal vertebra. MNN GDF 510 to MNN GDF 511 comprise two caudal vertebrae. All of the originalSuchomimus fossils are housed in the palaeontological collection of theMusée National du Niger.^[1] The initial description ofSuchomimus was preliminary. In 2007, thefurcula (wishbone)—found during an expedition in 2000—was described in detail.^[2]

S.tenerensis is potentially ajunior synonym of another spinosaurid from the Elrhaz Formation,Cristatusaurus lapparenti, named the same year based on jaw fragments and vertebrae.^[3] The skull elements were considered indistinguishable from those ofBaryonyx walkeri from theBarremian of England by British paleontologistsAlan Charig andAngela Milner.^[4] In 1997, while describingS.tenerensis, Sereno and colleagues agreed with this assessment and concluded thatCristatusaurus was adubious name.^[1] In 2002, the German palaeontologistHans-Dieter Sues and colleagues concluded thatSuchomimus was identical toCristatusaurus lapparenti, and despiteCristatusaurus having been named somewhat earlier thanSuchomimus, proposed them to represent a second species ofBaryonyx calledBaryonyx tenerensis.^[5] In a 2003 analysis, German paleontologistOliver Rauhut concurred with this.^[6] In a 2004conference abstract, Hutt and Newberry supported the synonymy based on a large theropod vertebra from the Isle of Wight, which they attributed to an animal closely related toBaryonyx andSuchomimus.^[7] Later studies have keptBaryonyx andSuchomimus separate, whereasCristatusaurus has been proposed to be either anomen dubium or possibly distinct from both.^{[8][9][10][11][12]} A 2017review paper by the palaeontologist Carlos Roberto A. Candeiro and colleagues stated that this debate was more in the realm of semantics than science, as it is generally agreed thatB. walkeri andS. tenerensis are distinct, related species.^[13] Barker and colleagues foundSuchomimus to be closer related to the British generaRiparovenator andCeratosuchops than toBaryonyx in 2021.^[14]

The length of thetype specimen ofSuchomimus, with undetermined age, reached 9.5–11 metres (31–36 ft) in length and weighed 2.5–3.8 metric tons (2.8–4.2 short tons).^[15][16][17] Therrein and Henderson proposed that a 10.3 metres (34 ft) longSuchomimus would have weighed more than 5.3 metric tons (5.8 short tons) based on their ratio between skull length and body length; however, they noted that they might have overestimated the size of spinosaurids (i.e.,Suchomimus andBaryonyx).^[18] The holotype ofSuchomimus was considerably larger than that ofBaryonyx, but the ages of the two individuals are not known.^[1][19]

Unlike most giant theropod dinosaurs,Suchomimus had a verycrocodilian-like skull, with a long, low snout and narrow jaws formed by a forward expansion of thepremaxillae (frontmost snout bones) and the hind branch of themaxillae (main upper jaw bone). The premaxillae had an upward branch, excluding the maxillae from theexternal nares (bony nostrils). The jaws had about 122 conical teeth, pointed but not very sharp and curving slightly backwards, with fineserrations and wrinkledenamel. The tip of the snout was enlarged sideways and carried a "terminalrosette" of longer teeth, seven per side in the premaxillae and about the same number in the corresponding part of the lower jaw. Further back, there were at least 22 teeth per upper jaw side in the maxilla, while the entire lower jaw side carried 32 teeth in the dentary bone.^[1]

The upper jaw had a prominent kink just behind the rosette, protruding downwards; this convexly curved part of the maxilla had the longest teeth of the entire skull. The internal bone shelves of the maxillae met each other in the midline of the skull over a long distance, forming a closedsecondary palate that stiffened the snout and setting off the internal nostrils and palatal complex (including thepterygoid,palatine, andectopterygoid) towards the back of the skull. The nostrils, unlike in most theropods, were retracted further back on the skull and behind the premaxillary teeth. The external nares were long, narrow, and horizontally positioned; the same was true of the largerantorbital fenestrae, a pair of bony openings in front of the eyes. The rear of the skull is poorly known but for a short quadrate bone, which had broad condyles (round protrusions) away from the centre of attachment and—like in the spinosauridBaryonyx—had a largeforamen (opening) separating it from thequadratojugal bone. The lower jaws were greatly elongated and narrow, forming a rigid structure as their dentaries touched each other at the midline, reinforcing themandible againsttorsional (bending and twisting) forces.^[1]

The neck was relatively short but well-muscled as shown by strongepipophyses (processes to which neck muscles attached). There were about sixteen dorsal vertebrae.Suchomimus had significantly extended neural spines—blade-shaped upward extensions on the vertebrae—which were elongated at the rear back. Those of the five sacral vertebrae were the longest. The elongation of these structures continued until the middle of the tail. The spines may have held up some kind of low crest orsail of skin that was highest over its hips, lower and extending further to the back than that ofSpinosaurus, in which the sail reached its highest peak over the dorsal vertebrae. This condition was more reduced inBaryonyx.^[1]

The furcula was V-shaped and indicates a high and narrow trunk.^[2] The scapula had a rectangularacromion, or attachment site forclavicle (collarbone). Thehumerus (upper arm bone) was very strongly built, only equaled in size among non-spinosaurid theropods by that ofMegalosaurus andTorvosaurus, with robust upper corners. The humerus had a boss (bone overgrowth) above thecondyle that contacted its hook-shapedradius (forearm bone). Accordingly, theulna of the lower arm was well-developed with an enormousolecranon (upper process set-off from the shaft), an exceptional trait shared withBaryonyx. The heavy arm musculature powered sizable hand claws, that of the firstdigit (or "thumb") being the largest with a length of 19 centimetres (7.5 inches). Only the thirdmetacarpal (long bone of the hand) is known, showing a robustmorphology (form). In thepelvis, theilium (main hip bone) was high. Thepubis (pubic bone) had a front surface that was wider than the side surface, and its forward-facing lower end was flattened and rectangular, with a brief flange along the midline, in contrast to the expanded boot shape it had in other theropods. Theischium (lower and rearmost hip bone) bore a lowobturator flange. Thefemur (thighbone) was straight and robust, with a length of 107 cm (42 in) in the holotype. Itslesser trochanter is markedly plate-like. In the ankle, theastragalus had an ascendingprocess taller than that ofAllosaurus.^[1]

The describers established someautapomorphies (unique derived traits) ofSuchomimus to separate it from other theropods, including the expanded rear dorsal, sacral, and front caudal neural spines, the robust upper corners of the humerus, and the boss above the humerus' condyle that contacted its hook-shaped radius.^[1] Sereno and colleagues referredSuchomimus to the Spinosauridae and named two subfamilies within thisclade, Baryonychinae (all spinosaurids more closely related toBaryonyx) and Spinosaurinae (all spinosaurids closer toSpinosaurus).Suchomimus was a member of thesubfamilyBaryonychinae. Apart from its apparently taller sail,Suchomimus was very similar to the spinosauridBaryonyx from theBarremian of England, and shared traits with it such as the reduced size and increased amount of teeth behind the snout tip in the mandible than spinosaurines, strong forelimbs, a huge sickle-curved claw on its "thumb", and strongly keeled front dorsal vertebrae. Spinosaurines are characterized by straight, unserrated, and more widely spaced teeth and the small size of their first premaxillary teeth. Sereno and colleagues pointed out that the more retracted nostrils inIrritator and the tall sail ofSpinosaurus could also be unique traits of spinosaurines, though material from other taxa is needed to know for sure.^[1] As withSuchomimus, the claw ofBaryonyx had been the first discovered fossil of the animal.^[1][19] Sereno and colleagues in 1998 analyzed the distribution of forty-five traits to produce acladogram that showedSuchomimus andBaryonyx to be distinct but closely related.^[1] Later, Barker and colleagues, in 2021, created a new tribe within Baryonychinae: Ceratosuchopsini, a clade that includesCeratosuchops,Riparovenator, andSuchomimus.^[14]

The followingphylogenetic tree shows a 2009 analysis of theMegalosauroidea.^[10]

Spinosaurids appear to have been widespread from theBarremian to theCenomanianstages of theCretaceousperiod, about 130 to 95 million years ago, while the oldest known spinosaurid remains date to theMiddle Jurassic.^[20] They shared features such as long, narrow, crocodile-like skulls; sub-circular teeth, with fine to no serrations; the terminal rosette of the snout; and a secondary palate that made them more resistant to torsion. In contrast, the primitive and typical condition for theropods was a tall, narrow snout with blade-like (ziphodont) teeth with serrated carinae.^[21] The skull adaptations of spinosauridsconverged with those ofCrocodilians; early members of the latter group had skulls similar to typical theropods, later developing elongated snouts, conical teeth, and secondary palates. These adaptations may have been the result of a dietary change from terrestrial prey to fish. Unlike crocodiles, the post-cranial skeletons of baryonychine spinosaurids do not appear to have aquatic adaptations.^[22][21] Sereno and colleagues proposed in 1998 that the large thumb-claw and robust forelimbs of spinosaurids evolved in the Middle Jurassic, before the elongation of the skull and other adaptations related to fish-eating, since the former features are shared with theirmegalosaurid relatives. They also suggested that the spinosaurines and baryonychines diverged before the Barremian age of the Early Cretaceous.^[1]

Several hypotheses have been proposed about thebiogeography of the spinosaurids. SinceSuchomimus was more closely related toBaryonyx (from Europe) than toSpinosaurus—although that genus also lived in Africa—the distribution of spinosaurids cannot be explained asvicariance resulting fromcontinental rifting.^[1] Sereno and colleagues proposed that spinosaurids were initially distributed across thesupercontinentPangea but split with the opening of theTethys Sea. Spinosaurines would then have evolved in the south (Africa and South America: inGondwana) and baryonychines in the north (Europe: inLaurasia), withSuchomimus the result of a single north-to-southdispersal event.^[1] Buffetaut and the Tunisian palaeontologist Mohamed Ouaja also suggested in 2002 that baryonychines could be the ancestors of spinosaurines, which appear to have replaced the former in Africa.^[23] Milner suggested in 2003 that spinosaurids originated in Laurasia during the Jurassic and dispersed via the Iberianland bridge into Gondwana, where theyradiated.^[24] In 2007, Buffetaut pointed out thatpalaeogeographical studies had demonstrated that Iberia was near northern Africa during the Early Cretaceous, which he found to confirm Milner's idea that the Iberian region was astepping stone between Europe and Africa, which is supported by the presence of baryonychines in Iberia. The direction of the dispersal between Europe and Africa is still unknown,^[25] and subsequent discoveries of spinosaurid remains in Asia and possibly Australia indicate that it may have been complex.^[26] The findings of Barkeret al. (2021) are consistent with Milner's findings, where Spinosauridae arose in Europe, and there were at least two migrations to Africa.^[14]

Charig and Milner had proposed apiscivorous (fish-eating) diet for the closely relatedBaryonyx in 1986. This was later confirmed in 1997 with the discovery of partially digested fish scales found in theBaryonyx holotype.^[19] In 1998, Sereno and colleagues suggested the same dietary preference forSuchomimus, based on its elongated jaws, spoon-shaped terminal rosette, and long teeth reminiscent of those of piscivorous crocodilians.^[1] American palaeontologistThomas Holtz noted that spinosaurid teeth were adapted for grasping rather than slicing, hence their reduced serrations, which in most other theropods were more prominent.Suchomimus's extensive secondary palate, which would have made the roof of the mouth more solid, allowed it to better resist twisting forces exerted by prey. The rest ofSuchomimus's body was not particularly adapted to the water.^[21] The discovery ofSuchomimus revealed that spinosaurid skulls were significantly shallower, more elongated, and narrower than previously thought.^[1]

The use of the robust forelimbs and giant claws of spinosaurs remains a debated topic. Charig and Milner speculated in 1986 thatBaryonyx may have crouched by the riverbank and used its claws togaff fish out of the water, similarly toGrizzly bears.^[27] In 1987, British biologist Andrew Kitchener hypothesized a use inscavenging carcasses,^[28] though this has been critiqued by other researchers who pointed out that in most cases, a carcass would have already been largely emptied out by its initial predators.^[29][19] A 2005 study by Canadian paleontologist François Therrien and colleagues posited that spinosaur forelimbs were probably used for hunting larger prey items, given that their snouts could not resist the bending stress.^[30] In a 2017 review of the family, David Hone and Holtz also considered possible functions in digging for water sources or hard-to-reach prey, as well as burrowing into soil to construct nests.^[29]

A 2022 study comparing the bone densities ofSuchomimus,Baryonyx, andSpinosaurus reveals that spinosaurids had ecologically disparate lifestyles.Suchomimus itself was more adapted to a life hunting in shallow water due to its hollow bones, whileBaryonyx andSpinosaurus were capable of fully submerging underwater and diving after prey. Courtesy of denser bones, the latter two spinosaurids could hunt underwater for prey and occupy a more derived lifestyle thanSuchomimus could.^[31][32][33]

The Elrhaz Formation, part of theTegama Group, consists mainly offluvial sandstones with low relief, much of which is obscured by sand dunes.^[34][35] Thesediments are coarse- to medium-grained, with almost no fine-grainedhorizons.^[36]Suchomimus lived in what is now Niger, during the lateAptian to earlyAlbian stages of theEarly Cretaceous, 112 million years ago.^[37][38] The sediment layers of the formation have been interpreted as an inland habitat of extensive freshwaterfloodplains and fast-moving rivers, with a tropical climate that likely experienced seasonal dry periods.^[37]

This environment was home to a variety of fauna, including dinosaurs,pterosaurs, turtles, fish,hybodont sharks, and freshwaterbivalves.^[38][35]Suchomimus coexisted with other theropods like theabelisauridKryptops palaios, thecarcharodontosauridEocarcharia dinops, and an unknownnoasaurid. Herbivorous dinosaurs of the region includediguanodontians likeOuranosaurus nigeriensis,Elrhazosaurus nigeriensis,Lurdusaurus arenatus, and twosauropods:Nigersaurus taqueti and an unnamedtitanosaur.Crocodylomorphs were abundant, represented by the giantpholidosaur speciesSarcosuchus imperator, as well as smallnotosuchians likeAnatosuchus minor,Araripesuchus wegeneri, andStolokrosuchus lapparenti.^[35] The local flora probably consisted mainly offerns,horsetails, andangiosperms, based on the dietary adaptations of the largediplodocoids that lived there.^[37]

• Paul Sereno – Project Exploration Suchomimus Fact Sheet, atProject Exploration.
• Photos of Suchomimus Skeleton in Niger, atProject Exploration.
• Video of mountedSuchomimus skeleton in Chicago at theField Museum