Spike Mouth the Spinosaurus

## Spike Mouth

Spike Mouth the Spinosaurus

Spike as is Spinosaurus It has a blue body with black stripes and a red sail. Spike Mouth It is a rampant but angry dinosaur He Is Villain

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***Spinosaurus*** **'spine lizard') is a genus of spinosaurid dinosaur that lived in what now is North Africa during the Cenomanian to upper Turonian stages of the Late Cretaceous period, about 99 to 93.5 million years ago. The genus was known first from Egyptian remains discovered in 1912 and described by German palaeontologist Ernst Stromer in 1915. The original remains were destroyed in World War II, but additional material came to light in the early 21st century. It is unclear whether one or two species are represented in the fossils reported in the scientific literature. The best known species is *S. aegyptiacus* from Egypt, although a potential second species, *S. maroccanus*, has been recovered from Morocco. The contemporary spinosaurid genus *Sigilmassasaurus* has also been synonymized by some authors with *S. aegyptiacus*, though other researchers propose it to be a distinct taxon. Another possible junior synonym is *Oxalaia* from the Alcântara Formation in Brazil.**

***Spinosaurus* is the longest known terrestrial carnivore; other large carnivores comparable to *Spinosaurus* include theropods such as *Tyrannosaurus*, *Giganotosaurus* and *Carcharodontosaurus*. The most recent study suggests that previous body size estimates are overestimated, and that *S. aegyptiacus* reached 14 metres (46 ft) in length and 7.4 metric tons (8.2 short tons) in body mass. The skull of *Spinosaurus* was long, low, and narrow, similar to that of a modern crocodilian, and bore straight conical teeth with no serrations. It would have had large, robust forelimbs bearing three-fingered hands, with an enlarged claw on the first digit. The distinctive neural spines of *Spinosaurus*, which were long extensions of the vertebrae (or backbones), grew to at least 1.65 meters (5.4 ft) long and were likely to have had skin connecting them, forming a sail-like structure, although some authors have suggested that the spines were covered in fat and formed a hump. The hip bones of *Spinosaurus* were reduced, and the legs were very short in proportion to the body. Its long and narrow tail was deepened by tall, thin neural spines and elongated chevrons, forming a flexible fin or paddle-like structure.**

***Spinosaurus* is known to have eaten fish, and most scientists believe that it hunted both terrestrial and aquatic prey. Evidence suggests that it was semiaquatic; how capable it was of swimming has been strongly contested. *Spinosaurus*'s leg bones had osteosclerosis (high bone density), allowing for better buoyancy control. Multiple functions have been put forward for the dorsal sail, including thermoregulation and display; either to intimidate rivals or attract mates. It lived in a humid environment of tidal flats and mangrove forests alongside many other dinosaurs, as well as fish, crocodylomorphs, lizards, turtles, pterosaurs, and plesiosaurs.**

## **Discovery and naming**

### **Naming of species**

**Two species of *Spinosaurus* have been named: *Spinosaurus aegyptiacus* (meaning "Egyptian spine lizard") and the disputed *Spinosaurus maroccanus* (meaning "Moroccan spine lizard"). The first described remains of *Spinosaurus* were found and described in the early 20th century. In 1912, Richard Markgraf discovered a partial skeleton of a giant theropod dinosaur in the Bahariya Formation of western Egypt. In 1915, German paleontologist Ernst Stromer published an article assigning the specimen to a new genus and species, *Spinosaurus aegyptiacus*.**

**Fragmentary additional remains from Bahariya, including vertebrae and hindlimb bones, were designated by Stromer as "*Spinosaurus B*" in 1934. Stromer considered them different enough to belong to another species, and this has been borne out. With the advantage of more expeditions and material, it appears that they pertain either to *Carcharodontosaurus* or to *Sigilmassasaurus*.**

***S. maroccanus* was originally described by Dale Russell in 1996 as a new species based on the length of its neck vertebrae. Specifically, Russell claimed that the ratio of the length of the centrum (body of vertebra) to the height of the posterior articular facet was 1.1 in *S. aegyptiacus* and 1.5 in *S. maroccanus*. Later authors have been split on this topic. Some authors note that the length of the vertebrae can vary from individual to individual, that the holotype specimen was destroyed and thus cannot be compared directly with the *S. maroccanus* specimen, and that it is unknown which cervical vertebrae the *S. maroccanus* specimens represent. Therefore, though some have retained the species as valid without much comment, most researchers regard *S. maroccanus* as a *nomen dubium* (dubious name) or as a junior synonym of *S. aegyptiacus*.**

### **Specimens**

**Six main partial specimens of *Spinosaurus* have been described. BSP 1912 VIII 19, described by Stromer in 1915 from the Bahariya Formation, was the holotype. The material consisted of the following items, most of which were incomplete: right and left dentaries and splenials from the lower jaw measuring 75 centimeters (30 in) long; a straight piece of the left maxilla that was described but not drawn; 20 teeth; 2 cervical vertebrae; 7 dorsal (trunk) vertebrae; 3 sacral vertebrae; 1 caudal vertebra; 4 thoracic ribs; and gastralia. Of the nine neural spines whose heights are given, the longest ("i," associated with a dorsal vertebra) was 1.65 meters (5.4 ft) in length. Stromer claimed that the specimen was from the early Cenomanian, about 97 million years ago.**

**It was destroyed in World War II, specifically "during the night of 24/25 April 1944 in a British bombing raid of Munich" that severely damaged the building housing the Paläontologisches Museum München (Bavarian State Collection of Paleontology). However, detailed drawings and descriptions of the specimen remain. Stromer's son donated Stromer's archives to the Paläontologische Staatssammlung München in 1995, and Smith and colleagues analysed two photographs of the *Spinosaurus* holotype specimen BSP 1912 VIII 19 discovered in the archives in 2000. On the basis of a photograph of the lower jaw and a photograph of the entire specimen as mounted, Smith concluded that Stromer's original 1915 drawings were slightly inaccurate. In 2003, Oliver Rauhut suggested that Stromer's *Spinosaurus* holotype was a chimera, composed of vertebrae and neural spines from a carcharodontosaurid similar to *Acrocanthosaurus* and a dentary from *Baryonyx* or *Suchomimus*. The analysis was rejected in at least one subsequent paper.**

**NMC 50791, held by the Canadian Museum of Nature, is a mid-cervical vertebra which is 19.5 centimeters (7.7 in) long from the Kem Kem Beds of Morocco. It is the holotype of *Spinosaurus maroccanus,* as described by Russell in 1996. Other specimens referred to *S. maroccanus* in the same paper were two other mid-cervical vertebrae (NMC 41768 and NMC 50790), an anterior dentary fragment (NMC 50832), a mid-dentary fragment (NMC 50833), and an anterior dorsal neural arch (NMC 50813). Russell stated that "only general locality information could be provided" for the specimen, and therefore it could be dated only "possibly" to the Albian.**

**MNHN SAM 124, housed at the Muséum National d'Histoire Naturelle, is a snout (consisting of partial premaxillae, partial maxillae, vomers, and a dentary fragment). Described by Taquet and Russell in 1998, the specimen is 13.4 to 13.6 centimeters (5.3–5.4 in) in width; no length was stated. The specimen was located in Algeria, and "is of Albian age." Taquet and Russell believed that the specimen, along with a premaxilla fragment (SAM 125), two cervical vertebrae (SAM 126–127), and a dorsal neural arch (SAM 128), belonged to *S. maroccanus*.**

**BM231 (in the collection of the Office National des Mines, Tunis) was described by Buffetaut and Ouaja in 2002. It consists of a partial anterior dentary 11.5 centimeters (4.5 in) in length from an early Albian stratum of the Chenini Formation of Tunisia. The dentary fragment, which included four alveoli and two partial teeth, was "extremely similar" to existing material of *S. aegyptiacus*.**

**UCPC-2 in the University of Chicago Paleontological Collection consists mainly of two narrow connected nasals with a fluted (ridged) crest from the region between the eyes. The specimen, which is 18.0 centimeters (7.1 in) long, was located in an early Cenomanian part of the Moroccan Kem Kem Beds in 1996 and described in the scientific literature in 2005 by Cristiano Dal Sasso of the Civic Natural History Museum in Milan and colleagues.**

**MSNM V4047 (in the Museo di Storia Naturale di Milano), described by Dal Sasso and colleagues in 2005, consists of a snout (premaxillae, partial maxillae, and partial nasals) 98.8 centimeters (38.9 in) long from the Kem Kem Beds. Like UCPC-2, it is thought to have come from the early Cenomanian. Arden and colleagues in 2018 tentatively assigned this specimen to *Sigilmassasaurus brevicollis* given its size. However, this assignment was later rejected by other researchers who considered the uniqueness of this specimen to be based on misinterpretations and poor preservation of another specimen, NHMUK R16665, another snout stored that is stored in the Natural History Museum, London.**

**FSAC-KK 11888 is a partial subadult skeleton recovered from the Kem Kem beds of North Africa. Described by Ibrahim and colleagues (2014) and designated as the neotype specimen (although Evers and colleagues 2015 reject the neotype designation for FSAC-KK-11888). It includes cervical vertebrae, dorsal vertebrae, neural spines, a complete sacrum, femora, tibiae, pedal phalanges, caudal vertebra, several dorsal ribs, and fragments of the skull. The body proportions of the specimen have been debated, as the hind limbs are disproportionately shorter in the specimen than in previous reconstructions. However, it has been demonstrated by multiple paleontologists that the specimen is not a chimera, and is indeed a specimen of *Spinosaurus* that suggests that the animal had much smaller hind limbs than previously thought.**

**Other known specimens consist mainly of very fragmentary remains and scattered teeth. These include:**

* **A 1986 paper described prismatic structures in tooth enamel from two *Spinosaurus* teeth from Tunisia.**
* **Buffetaut (1989, 1992) referred three specimens from the Institut und Museum für Geologie und Paläontologie of the University of Göttingen in Germany to *Spinosaurus*: a right maxilla fragment IMGP 969-1, a jaw fragment IMGP 969-2, and a tooth IMGP 969-3. These had been found in a Lower Cenomanian or Upper Albian deposit in southeastern Morocco in 1971.**
* **Kellner and Mader (1997) described two unserrated spinosaurid teeth from Morocco (LINHM 001 and 002) that were "highly similar" to the teeth of the *S. aegyptiacus* holotype.**
* **Teeth from the Chenini Formation in Tunisia which are "narrow, somewhat rounded in cross-section, and lack the anterior and posterior serrated edges characteristic of theropods and basal archosaurs" were assigned to *Spinosaurus* in 2000.**
* **Teeth from the Echkar Formation of Niger were tentatively referred to *Spinosaurus* in 2007.**
* **A partial tooth 8 centimeters (3.1 in) long purchased at a fossil trade show, reportedly from the Kem Kem Bed of Morocco and attributed to *Spinosaurus maroccanus*, showed 1 to 5 millimeters (0.039 to 0.197 in) wide longitudinal striations and micro-structures (irregular ridges) among the striations in a 2010 paper.**

**MHNM.KK374 to .KK378 are five isolated quadrates (skull bones) of different sizes that were collected by locals and acquired commercially in the Kem Kem region of southeastern Morocco, provided by François Escuillié and are deposited in the collections of the Muséum d’Histoire Naturelle of Marrakech. The quadrates show two different morphologies, suggesting the existence of two spinosaurines in Morocco. However, a 2020 study on variation within *Spinosaurus* considers these differences in morphology to be indicative of variation in skull morphology within a single species, as is the case in *Allosaurus.***

#### **Possible specimens**

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**Material possibly belonging to *Spinosaurus* has been reported from the Turkana Grits of Kenya.**

**Some scientists have considered the genus *Sigilmassasaurus* a junior synonym of *Spinosaurus*. In Ibrahim and colleagues (2014), the specimens of *Sigilmassasaurus* was referred to *Spinosaurus aegyptiacus* together with "Spinosaurus B" as the neotype and *Spinosaurus maroccanus* was considered as a *nomen dubium* following the conclusions of the other papers. A 2015 re-description of *Sigilmassasaurus* disputed these conclusions, and considered the genus valid. This conclusion was further supported in 2018 by Arden and colleagues, who consider *Sigilmassasaurus* to be a distinct genus, though a very close relative of *Spinosaurus*, the two unified in the tribe Spinosaurini, coined in the study.**

**In a 2020 paper written by Symth *et al.* in assessing spinosaurine specimens from the Kem Kem Group suggested the Brazilian spinosaurine *Oxalaia* to be a potential junior synonym of *Spinosaurus aegyptiacus*. This was based on looking at the specimens assigned to *Oxalaia*, and the supposed autapomorphies of this taxon to be insignificant and fall within the hypodigm of *Spinosaurus aegyptiacus*. If supported by future studies, this would imply *Spinosaurus aegyptiacus* had a wider distribution and supports the faunal exchange between South America and Africa during this time. Additionally, the study further indicates synonymy between *Spinosaurus* and *Sigilmassasaurus*.**

## **Description**

### **Size**

**Since its discovery, *Spinosaurus* has been a contender for the largest theropod dinosaur. Both Friedrich von Huene in 1926 and Donald F. Glut in 1982 listed it as among the most massive theropods in their surveys, at 15 meters (49 ft) in length and upwards of 6 metric tons (6.6 short tons) in weight. In 1988, Gregory S. Paul also listed it as the longest theropod at 15 meters (49 ft), but gave a lower mass estimate of 4 metric tons (4.4 short tons).**

**In 2005, Dal Sasso and colleagues assumed that *Spinosaurus* and the spinosaurid *Suchomimus* had the same body proportions in relation to their skull lengths, and thereby calculated that *Spinosaurus* was 16 to 18 meters (52 to 59 ft) in length and 7 to 9 metric tons (7.7 to 9.9 short tons) in weight. The estimates were criticized because the skull length estimate was uncertain, and (assuming that body mass increases as the cube of body length) scaling *Suchomimus,* which was 11 meters (36 ft) long and 3.8 metric tons (4.2 short tons) in mass, to the range of estimated lengths of *Spinosaurus* would produce an estimated body mass of 11.7 to 16.7 metric tons (12.9 to 18.4 short tons).**

**François Therrien and Donald Henderson, in a 2007 paper using scaling based on skull length, challenged previous estimates of the size of *Spinosaurus*, finding the length too great and the weight too small. Based on estimated skull lengths of 1.5 to 1.75 meters (4.9 to 5.7 ft), their estimates include a body length of 12.6 to 14.3 meters (41 to 47 ft) and a body mass of 12 to 20.9 metric tons (13.2 to 23.0 short tons). The lower estimates for *Spinosaurus* would imply that the animal was shorter and lighter than *Carcharodontosaurus* and *Giganotosaurus*. The Therrien and Henderson study has been criticized for the choice of theropods used for comparison (e.g., most of the theropods used to set the initial equations were tyrannosaurids and carnosaurs, which have a different build than spinosaurids), and for the assumption that the *Spinosaurus* skull could be as little as 1.5 meters (4.9 ft) in length.**

**In 2014, Ibrahim and his colleagues suggested that *Spinosaurus aegyptiacus* could reach over 15 metres (49 ft) in length. In 2022, however, Paul Sereno and his colleagues suggested that *Spinosaurus aegyptiacus* reached a maximum body length of 14 metres (46 ft) and a maximum body mass of 7.4 metric tons (8.2 short tons) by constructing a CT-based 3D skeletal model "with the axial column in neutral pose." They argued that the 2D graphical reconstruction of the aquatic hypothesis by Ibrahim and his colleagues in 2020 overestimated the presacral column length by 10%, ribcage depth by 25%, and forelimb length by 30% over dimensions based on CT-scanned fossils; these proportional overestimates shift the center of mass anteriorly when translated to a flesh model, and thus the estimate from Ibrahim and his colleagues cannot be considered a reliable body size estimate.**

### **Skull**

**Its skull had a narrow snout filled with straight conical teeth that lacked serrations. There were six or seven teeth on each side of the very front of the upper jaw, in the premaxillae, and another twelve in both maxillae behind them. The second and third teeth on each side were noticeably larger than the rest of the teeth in the premaxilla, creating a space between them and the large teeth in the front of the maxilla; large teeth in the lower jaw faced this space. The very tip of the snout holding those few large front teeth was expanded, and a small crest was present in front of the eyes. Using the dimensions of three specimens known as MSNM V4047, UCPC-2, and BSP 1912 VIII 19, and assuming that the postorbital part of the skull of MSNM V4047 had a shape similar to the postorbital part of the skull of *Irritator*, Dal Sasso and colleagues (2005) estimated that the skull of *Spinosaurus* was 1.75 meters (5.7 ft) long, but more recent estimates suggest a length of 1.6–1.68 meters (5.2–5.5 ft). The Dal Sasso and colleagues skull length estimate is questioned because skull shapes can vary across spinosaurid species and because MSNM V4047 may not belong to *Spinosaurus* itself.**

### **Postcranial skeleton**

**As a spinosaurid, *Spinosaurus* would have had a long, muscular neck, curved in a sigmoid, or S-shape. Its shoulders were prominent, and the forelimbs large and stocky, bearing three clawed digits on each hand. The first finger (or "thumb") would have been the largest. *Spinosaurus* had long phalanges (finger bones), and only somewhat recurved claws, suggesting that its hands were longer compared to those of other spinosaurids.**

**Very tall neural spines growing on the back vertebrae of *Spinosaurus* formed the basis of what is usually called the animal's "sail". The lengths of the neural spines reached over 10 times the diameters of the centra (vertebral bodies) from which they extended. The neural spines were slightly longer front to back at the base than higher up, and were unlike the thin rods seen in the pelycosaur finbacks *Edaphosaurus* and *Dimetrodon*, contrasting also with the thicker spines in the iguanodontian *Ouranosaurus*.**

***Spinosaurus* sails were unusual, although other dinosaurs, namely *Ouranosaurus*, which lived a few million years earlier in the same general region as *Spinosaurus*, and the South American sauropod *Amargasaurus,* might have developed similar structural adaptations of their vertebrae. The sail may be an analog of the sail of the Permian synapsid *Dimetrodon*, which lived before the dinosaurs even appeared, produced by convergent evolution.**

**The structure may also have been more hump-like than sail-like, as noted by Stromer in 1915 ("one might rather think of the existence of a large hump of fat [German: *Fettbuckel*], to which the [neural spines] gave internal support") and by Jack Bowman Bailey in 1997. In support of his "buffalo-back" hypothesis, Bailey argued that in *Spinosaurus*, *Ouranosaurus*, and other dinosaurs with long neural spines, the spines were relatively shorter and thicker than the spines of pelycosaurs (which are known to have sails); instead, the dinosaurs' neural spines were similar to the neural spines of extinct hump-backed mammals such as *Megacerops* and *Bison latifrons*. In 2014, Ibrahim and colleagues instead posited that the spines were covered tightly by skin, similar to a crested chameleon, given their compactness, sharp edges, and likely poor blood flow.**

***Spinosaurus* had a significantly smaller pelvis (hip bone) than that of other giant theropods, with the surface area of the ilium (main body of the pelvis) half that of most members of the clade. The hind limbs were short, at just over 25 percent of the total body length, with the tibia (calf bone) being longer than the femur (thigh bone). Unlike in other theropods, the hallux (or fourth toe) of *Spinosaurus* touched the ground, and the phalanges of the toe bones were unusually long and well-built. At their ends were shallow claws that had flat bottoms. This type of foot morphology is also seen in shorebirds, indicating that *Spinosaurus*'s feet evolved for walking across unstable substrate and that they may have been webbed.**

**From the caudal vertebrae of the tail projected significantly elongated, thin neural spines, akin to the condition observed in some other spinosaurids, though to a more extreme degree. Coupled with the also elongated chevron bones on the underside of the caudals, this resulted in a deep and narrow tail with a paddle or fin-like shape, comparable to the tails of newts and crocodilians.**

## **Classification**

***Spinosaurus* gives its name to the dinosaur family Spinosauridae, which includes two subfamilies: Baryonychinae and Spinosaurinae. Baryonychinae includes *Baryonyx* from southern England and *Suchomimus* from Niger in central Africa. Spinosaurinae includes *Spinosaurus*, *Sigilmassasaurus*, *Oxalaia*, *Siamosaurus*, *Ichthyovenator*, *Irritator* from Brazil, and *Angaturama* (which may be synonymous with *Irritator*) from Brazil. The spinosaurines share unserrated straight teeth that are widely spaced (e.g., 12 on one side of the maxilla), as opposed to the baryonychines, which have serrated curved teeth that are numerous (e.g., 30 on one side of the maxilla).**

**An analysis of Spinosauridae by Arden and colleagues (2018) named the clade Spinosaurini and defined it as all spinosaurids closer to *Spinosaurus aegyptiacus* than to *Irritator challengeri* or *Oxalaia quilombensis*; it also found *Siamosaurus suteethorni* and *Icthyovenator laosensis* to be members of Spinosaurinae.**

### **Phylogeny**

**The subfamily Spinosaurinae was named by Sereno in 1998, and defined by Holtz and colleagues (2004) as all taxa closer to *Spinosaurus aegyptiacus* than to *Baryonyx walkeri*. The subfamily Baryonychinae was named by Charig & Milner in 1986. They erected both the subfamily and the family Baryonychidae for the newly discovered *Baryonyx*, before it was referred to Spinosauridae. Their subfamily was defined by Holtz and colleagues in 2004, as the complementary clade of all taxa closer to *Baryonyx walkeri* than to *Spinosaurus aegyptiacus*. Examinations by Marcos Sales, Cesar Schultz, and colleagues (2017) indicate that the South American spinosaurids *Angaturama*, *Irritator*, and *Oxalaia* were intermediate between Baronychinae and Spinosaurinae based on their craniodental features and cladistic analysis. This indicates that Baryonychinae may in fact be non-monophyletic. Their cladogram can be seen below.**