Spinosaurus
Spinosaurus | |
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Reconstructed skeleton based on specimen FSAC-KK-11888 in swimming posture, Field Museum of Natural History | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Family: | †Spinosauridae |
Tribe: | † Spinosaurini
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Genus: | †Spinosaurus Stromer, 1915 |
Type species | |
†Spinosaurus aegyptiacus Stromer, 1915
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Synonyms | |
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Spinosaurus (
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.[4] 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.[5] 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
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").[6][7] 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.[8][6]
Fragmentary additional remains from Bahariya, including vertebrae and hindlimb bones, were designated by Stromer as "Spinosaurus B" in 1934.[9] 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[10] or to Sigilmassasaurus.[7]
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.[7] 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,[11][12][13] most researchers regard S. maroccanus as a nomen dubium (dubious name)[14][15][16] or as a junior synonym of S. aegyptiacus.[10]
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
It was destroyed in
NMC 50791, held by the
MNHN SAM 124, housed at the
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
UCPC-2 in the
MSNM V4047 (in the
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).[19] 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.[20] 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.[21][22][23]
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.[24]
- 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.[25][26] These had been found in a Lower Cenomanian or Upper Albian deposit in southeastern Morocco in 1971.[25]
- 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.[27]
- 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.[28]
- Teeth from the Echkar Formation of Niger were tentatively referred to Spinosaurus in 2007.[29]
- 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.[13]
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.[30] 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.[1]
Possible specimens
Material possibly belonging to Spinosaurus has been reported from the
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
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.[1]
Description
Size
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.[14] 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).[36]
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.
In 2014, Ibrahim and his colleagues suggested that Spinosaurus aegyptiacus could reach over 15 metres (49 ft) in length.[20] 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."[4] They argued that the 2D graphical reconstruction of the aquatic hypothesis by Ibrahim and his colleagues in 2020[39] 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.[4]
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,[14] but more recent estimates suggest a length of 1.6–1.68 meters (5.2–5.5 ft).[30][40] 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.[36][18]
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.[20][18][41]
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.[42][43] 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.[42]
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
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 [
Spinosaurus had a significantly smaller
From the caudal vertebrae of the tail projected significantly elongated, thin neural spines, akin to the condition observed in some other spinosaurids,[18] 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.[45]
Classification
Spinosaurus gives its name to the dinosaur
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.[18]
Phylogeny
The subfamily Spinosaurinae was named by Sereno in 1998, and defined by
Spinosauridae |
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The cladogram below depicts the findings of Arden and colleagues (2018):[18]
Spinosauridae |
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Paleobiology
Function of neural spines
The function of the dinosaur's sail or hump is uncertain; scientists have proposed several hypotheses including heat regulation and display. In addition, such a prominent feature on its back could make it appear even larger than it was, intimidating other animals.[42]
The structure may have been used for
Many elaborate body structures of modern-day animals serve to attract members of the opposite sex during mating. It is possible that the sail of Spinosaurus was used for courtship, in a way similar to a
Gimsa and colleagues (2015) suggest that the dorsal sail of Spinosaurus was analogous to the dorsal fins of sailfish and served a hydrodynamic purpose.[48] Gimsa and others point out that more basal, long-legged spinosaurids had otherwise round or crescent-shaped dorsal sails, whereas in Spinosaurus, the dorsal neural spines formed a shape that was roughly rectangular, similar in shape to the dorsal fins of sailfish. They therefore argue that Spinosaurus used its dorsal neural sail in the same manner as sailfish, and that it also employed its long narrow tail to stun prey like a modern thresher shark. Sailfish employ their dorsal fins for herding schools of fish into a "bait ball" where they cooperate to trap the fish into a certain area where the sailfish can snatch the fish with their bills. The sail could have possibly reduced yaw rotation by counteracting the lateral force in the direction opposite to the slash as suggested by Gimsa and colleagues (2015). They specifically wrote:[48]
Spinosaurus anatomy exhibits another feature that may have a modern analogy: its long tail resembled that of the thresher shark, employed to slap the water to herd and stun shoals of fish before devouring them (Oliver and colleagues, 2013). The strategies that sailfish and thresher sharks employ against shoaling fish are more effective when the shoal is first concentrated into a ‘bait ball’ (Helfman, Collette & Facey, 1997; Oliver and colleagues, 2013; Domenici and colleagues, 2014). Since this is difficult for individual predators to achieve, they cooperate in this effort. When herding a shoal of fish or squid, sailfish also raise their sails to make themselves appear larger. When they slash or wipe their bills through shoaling fish by turning their heads, their dorsal sail and fins are outstretched to stabilize their bodies hydrodynamically (Lauder & Drucker, 2004). Domenici and colleagues (2014) postulate that these fin extensions enhance the accuracy of tapping and slashing. The sail can reduce yaw rotation by counteracting the lateral force in the direction opposite to the slash. This means that prey is less likely to recognize the massive trunk as being part of an approaching predator (Marras and colleagues, 2015; Webb & Weihs 2015).[48]
Spinosaurus exhibited the anatomical features required to combine all three hunting strategies: a sail for herding prey more efficiently, as well as flexible tail and neck to slap the water for stunning, injuring or killing prey. The submerged dorsal sail would have provided a strong centreboard-like counterforce for powerful sidewards movements of the strong neck and long tail, as performed by sailfish (Domenici and colleagues, 2014) or thresher sharks (Oliver and colleagues, 2013). While smaller dorsal sails or fins make the dorsal water volume better accessible for slashing, it can be speculated that their smaller stabilization effect makes lateral slashing less efficient (e.g. for thresher sharks). Forming a hydrodynamic fulcrum and hydrodynamically stabilizing the trunk along the dorsoventral axis, Spinosaurus’ sail would also have compensated for the inertia of the lateral neck by tail movements and vice versa not only for predation but also for accelerated swimming. This behavior might also have been one reason for Spinosaurus’ muscular chest and neck reported by Ibrahim and colleagues (2014).[48]
Diet and feeding
It is unclear whether Spinosaurus was primarily a terrestrial predator or a
In 2009, Dal Sasso and colleagues. reported the results of
Aquatic habits
A 2010 isotope analysis by Romain Amiot and colleagues found that oxygen isotope ratios of spinosaurid teeth, including teeth of Spinosaurus, indicate semiaquatic lifestyles. Isotope ratios from tooth enamel and from other parts of Spinosaurus (found in Morocco and Tunisia) and of other predators from the same area such as Carcharodontosaurus were compared with isotopic compositions from contemporaneous theropods, turtles, and crocodilians. The study found that Spinosaurus teeth from five of six sampled localities had oxygen isotope ratios closer to those of turtles and crocodilians when compared with other theropod teeth from the same localities. The authors postulated that Spinosaurus switched between terrestrial and aquatic habitats to compete for food with large crocodilians and other large theropods respectively.[54] A 2018 study by Donald Henderson, however, refutes the claim that Spinosaurus was semiaquatic. By studying the buoyancy in lungs of crocodilians and comparing it to the lung placement in Spinosaurus, it was discovered that Spinosaurus could not sink or dive below the water surface. It was also capable of keeping its entire head above the water surface while floating, much like other non-aquatic theropods. Furthermore, the study found that Spinosaurus had to continually paddle its hind legs to prevent itself from tipping over onto its side, something that extant semiaquatic animals do not need to perform. Henderson therefore theorized that Spinosaurus probably did not hunt completely submerged in water as previously hypothesized, but instead would have spent much of its time on land or in shallow water.[55][56]
Recent studies of the tail vertebrae of Spinosaurus refute Henderson's proposal that Spinosaurus mainly inhabited areas of land near and in shallow water and was too buoyant to submerge. Studies of the tail, thanks to fossils recovered and analyzed by Ibrahim, Pierce, Lauder, and Sereno and colleagues in 2018 indicate that Spinosaurus had a keeled tail that was well adapted to propelling the animal through water. The elongated neural spines and chevrons, which run to the end of the tail on both dorsal and ventral sides, indicate that Spinosaurus was able to swim in a similar manner to modern crocodilians. Through experimentation by Lauder and Pierce, the tail of Spinosaurus was found to have eight times as much forward thrust as the tails of terrestrial theropods like Coelophysis and Allosaurus, as well as being twice as efficient at achieving forward thrust. The discovery indicates that Spinosaurus may have had a lifestyle comparable to modern alligators and crocodiles, remaining in water for long periods of time while hunting.[45]
David Hone and
A 2022 study by Fabbri et al., made comparisons of Spinosaurus' bone structure and compared it to that of Baryonyx and Suchomimus. The study revealed that Spinosaurus and Baryonyx had dense bones, which allowed them to dive and pursue prey underwater. Compared to these, Suchomimus had more hollow bones, suggesting it preferred to hunt in shallow water. These findings also suggest that various spinosaurid genera were more ecologically disparate than previously believed, as some were better suited to hunting in subaqueous environments than other, closely related genera.[58][59][60]
In the same year, contradicting the study by Fabbri and colleagues, Sereno and his colleagues suggested that Spinosaurus was wholly bipedal on land and an unstable, slow moving surface swimmer in deep water. Their results, taken from reconstructing a CT model of the skeleton, and then adding internal air and muscles. Their results, coupled with fossils from Spinosaurus that showed it also lived further inland along rivers and lakes, suggest it was a semi-aquatic, ambush piscivore that preferred waterside environments both along the coasts and further inland along rivers and lakes. Simultaneously, they suggested that the large tail fin was probably utilized more for display than swimming, as tails in living animals have the same function when they possess comparably tall neural spines.[4]
Locomotion and posture
Although traditionally depicted in the scientific community as a biped, Spinosaurus was often depicted in the mid-20th century as an obligate quadruped akin to Dimetrodon.[61] Starting in the mid-1970s, it was hypothesized Spinosaurus was at least an occasional quadruped,[34][47] bolstered by the discovery of Baryonyx, a relative with robust arms.[62] Because of the mass of the hypothesized fatty dorsal humps of Spinosaurus, Bailey (1997) was open to the possibility of a quadrupedal posture,[42] leading to new restorations of it as such.[62] Theropods, including spinosaurids, could not pronate their hands (rotate the forearm so the palm faced the ground),[63] but a resting position on the side of the hand was possible, as shown by fossil prints from an Early Jurassic theropod.[64] The hypothesis that Spinosaurus had a typical quadrupedal gait since fell out of favor, however it was still believed that spinosaurids may have crouched in a quadrupedal posture, due to biological and physiological constraints.[49][63]
The possibility of a quadrupedal Spinosaurus was revived by a 2014 paper by
A 2024 article co-authored by Sereno stated that the previous calculations by Sereno that were used to argue quadrupedality for Spinosaurus had erroneously shifted the center of mass in front of the hips. They instead suggested that the dinosaur fit the criteria of being a graviportal (or slow-moving) biped.[68][69]
Ontogeny
An ungual phalanx measuring 21 millimeters (0.83 in) belonging to a very young juvenile Spinosaurus indicates that the theropod developed its semiaquatic adaptations at a very young age or at birth and maintained them throughout its life. The specimen, found in 1999 and described by Simone Maganuco and Cristiano Dal Sasso and colleagues, is believed to have come from an animal measuring 1.78 meters (5.8 ft) (assuming it resembled a smaller version of the adult), making it the smallest specimen of Spinosaurus currently known.[70]
Paleoenvironment
The environment inhabited by Spinosaurus is only partially understood, and covers a great deal of what is now northern Africa. The region of Africa Spinosaurus is preserved in dates from 112 to 93.5 million years ago,
In popular culture
Spinosaurus appeared in the 2001 film
Spinosaurus has long been depicted in popular books about dinosaurs, although only recently has there been enough information about spinosaurids for an accurate depiction. After an influential 1955 skeletal reconstruction by Lapparent and Lavocat[84] based on a 1936 diagram by Stromer,[85] it has been treated as a generalized upright theropod, with a skull similar to that of other large theropods and a sail on its back, even having four-fingered hands.[62]
In addition to films, action figures, video games, and books, Spinosaurus has been depicted on postage stamps from countries such as Angola, The Gambia, and Tanzania.[86][87]
See also
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- ^ Portman, J. (July 11, 2001). "Spinosaurus makes T. Rex look like a pussycat: When it comes to Jurassic Park III, size does matter". Ottawa Citizen.
- ^ Chandler, G. (August 2001). "A bite-size guide to the dinosaurs of the new movie Jurassic Park III". National Geographic World.
- ^ Romano, Nick (June 2015). "Jurassic World Snuck in A Sweet Nod to Jurassic Park 3". CinemaBlend.
- ^ Orquiola, John (July 23, 2022). "Jurassic World Finally Has A Proper T-Rex vs Spinosaurus Rematch". Screen Rant. Retrieved February 7, 2024.
- CBR.com. Retrieved February 7, 2024.
- ^ Lapparent, A.F. de; and Lavocat, R. (1955). "Dinosauriens." In: Piveteau, J., editor. Traité de Paléontologie. Tome V. La Sortie des Eaux. Naissance de la Tétrapodie. L'Exubérance de la Vie Végétative. La Conquête de l'Air. Amphibiens. Reptiles. Oiseaux. Paris: Masson et Cie, pp. 785–962.
- ^ Stromer, E. (1936). "Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. VII. Baharije-Kessel und -Stufe mit deren Fauna und Flora. Eine ergänzende Zusammenfassung". Abhandlungen der Bayerischen Akademie der Wissenschaften, Mathematisch-naturwissenschaftliche Abteilung. Neue Folge (in German). 33: 1–102.
- ^ Khatri, V.S. (June 9, 2006). "From the past". The Hindu. Archived from the original on June 18, 2006. Retrieved September 12, 2010.
- ISBN 978-0-253-21313-6. Retrieved September 12, 2010.
Further reading
- Glut, D.F. "In search of Spinosaurus." In: Jurassic classics: a collection of saurian essays and Mesozoic musings, pp. 77–85. Jefferson, NC: McFarland, 2001. ISBN 0-7864-0961-4.
- Nothdurft, W.; and Smith, J. The Lost Dinosaurs of Egypt. New York: Random House, 2002. ISBN 0-375-50795-7.
- A Tribute to Ernst Stromer: Hundred Years of the Discovery of Spinosaurus aegyptiacus: Saubhik Ghosh
External links
- "A Strange Dinosaur May Have Swum the Rivers of Africa". Spinosaurus profile by Kenneth Chang at NY Times, April 29, 2020
- Hartman, Scott. Spinosaur Comparison. SkeletalDrawing.com, 2006.
- Mortimer, Mickey. Spinosaurus Stromer, 1915. (List of specimens from The Theropod Database.)
- Natural History Museum. Dino Directory: Spinosaurus.
- Prendergast, John. Dinosaurs Lost and Found. The Pennsylvania Gazette, the Alumni Magazine of the University of Pennsylvania, July/Aug 2001.