Spinosaurus

Spinosaurus

Taxobox
name = "Spinosaurus"
fossil_range = Early-Late Cretaceous



image_width = 250px
image_caption = "Spinosaurus aegyptiacus"
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Saurischia
subordo = Theropoda
familia = Spinosauridae
subfamilia = Spinosaurinae
genus = "Spinosaurus"
genus_authority = Stromer, 1915
subdivision_ranks = Species
subdivision =
*"S. aegyptiacus" Stromer, 1915 (type)
*?"S. marocannus" Russell, 1996

"Spinosaurus" (meaning "spine lizard") is a genus of theropod dinosaur which lived in what is now North Africa, from the Albian to early Cenomanian stages of the Cretaceous Period, about 100 to 93 million years ago. This genus was first known from Egyptian remains discovered in the 1910s and described by German paleontologist Ernst Stromer. These original remains were destroyed in World War II, but additional skull material has come to light in recent years. It is unclear whether one or two species are represented in the described fossils. The best known species is "S. aegyptiacus" from Egypt, although a potential second species, "S. marocannus", has been recovered from Morocco.

The distinctive spines of "Spinosaurus", which were long extensions of the vertebrae, grew up to m to ft|2 long and were likely to have had skin connecting them, forming a sail-like structure, although some authors have suggested that they were covered in muscle and formed a hump or ridge. Multiple functions have been put forward for this structure, including thermoregulation and display. According to recent estimates, "Spinosaurus" is the largest of all known carnivorous dinosaurs, even larger than "Tyrannosaurus rex" and "Giganotosaurus". These estimates suggest that it was around convert|16|to|18|m|ft|1 in length and 7 to 9 tonnes (7.7 to 9.9 tons) in weight.cite journal |last=dal Sasso |first=C. |coauthors=Maganuco, S.; Buffetaut, E.; and Mendez, M.A. |year=2005 |title=New information on the skull of the enigmatic theropod "Spinosaurus", with remarks on its sizes and affinities |journal=Journal of Vertebrate Paleontology |volume=25 |issue=4 |pages=888–896|url=http://www.bioone.org/perlserv/?request=get-abstract&doi=10.1671%2F0272-4634%282005%29025%5B0888%3ANIOTSO%5D2.0.CO%3B2|doi=10.1671/0272-4634(2005)025 [0888:NIOTSO] 2.0.CO;2]

Description

Although "Spinosaurus" is well-known to dinosaur enthusiasts due to its size, sail, and elongated skull, it is mostly known from remains that have been destroyed, aside from a few more recently discovered teeth and skull elements. Additionally, so far only the skull and backbone have been described in detail, and limb bones have not been found. Jaw and skull material published in 2005 show that it had one of the longest skulls of any carnivorous dinosaur, estimated at about 1.75 meters long (5.75 ft). The 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 premaxilla bones, 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 anterior maxilla; large teeth in the lower jaw faced this space. The very tip of the snout holding those few large anterior teeth was expanded, and a small crest was present in front of the eyes.

The sail of "Spinosaurus" was formed of very tall neural spines growing on the back vertebrae. These spines were seven to eleven times the height of the vertebrae from which they grew.cite book |last=Molnar |first=Ralph E. |coauthors=Kurzanov, Sergei M.; and Dong Zhiming |year=1990 |chapter=Carnosauria |editors=Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.) |title=The Dinosauria |edition=1st |publisher=University of California Press |location=Berkeley |pages=169–209 |isbn=0-520-06727-4] The 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".

Classification

clade| style=font-size:80%;line-height:80%
label1= Spinosauridae
1=clade
1= ?"Chilantaisaurus"
2= ?"Suchosaurus"
3=clade
label1= Baryonychinae
1=clade
1= "Baryonyx"
2= "Cristatusaurus"
3= "Suchomimus"

4=clade
label1= Spinosaurinae
1=clade
1= "Irritator"
2= "Angaturama"
3= ?"Siamosaurus"
4= "Spinosaurus"
"Spinosaurus" gives its name to a family of dinosaurs, the Spinosauridae, of which other members include "Baryonyx" from southern England, "Irritator" and "Angaturama" (which is probably synonymous with "Irritator") from Brazil, "Suchomimus" from Niger in central Africa, and possibly "Siamosaurus", which is known from fragmentary remains in Thailand. "Spinosaurus" is closest to "Irritator", which shares its unserrated straight teeth, and the two are included in the subfamily Spinosaurinae.cite book|title=The Dinosauria (second edition)|year=2004|chapter=Basal Tetanurae|author=Holtz, Jr., T.R., Molnar, R.E, and Currie, P.J.|pages=71–110|publisher=University of California Press|id=ISBN 0-520-24209-2] In 2003, Oliver Rauhut suggested that Stromer's "Spinosaurus" holotype was a chimera, composed of back vertebrae from a carcharodontosaurid similar to "Acrocanthosaurus" and a dentary from a large theropod similar to "Baryonyx".cite journal | author = Rauhut, O.W.M. | year = 2003 | title = The interrelationships and evolution of basal theropod dinosaurs | journal = Special Papers in Palaeontology | volume = 69 | pages = 1–213] This analysis, however, has been rejected in recent papers.

Discovery and species

The first described remains of "Spinosaurus" were found in the Bahariya Valley of Egypt in 1912, and were named by German paleontologist Ernst Stromer in 1915.cite journal |last=Stromer |first=E. |authorlink=Ernst Stromer |year=1915 |title=Wirbeltier-Reste der baharije-Stufe (unterstes Cenoman).3. Das Origianl des Theropoden "Spinosaurus aegyptiacus" nov. gen. et nov. spec |journal=Abhandlungen der Königlich Bayerischen Akademie der Wissenschaften Mathematisch-physikalische Klasse Abhandlung |volume=28 |pages=1–32 |language=German] Fragmentary additional remains from Bahariya, including vertebrae and hindlimb bones, were designated by Stromer as "Spinosaurus" B" in 1934.cite journal |last=Stromer |first=E. |authorlink=Ernst Stromer |year=1934 |title=Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltierreste der Baharîje-Stufe (unterstes Cenoman). 13. Dinosauria |journal=Abhandlungen der Bayerischen Akademie der Wissenschaften Mathematisch-naturwissenschaftliche Abteilung, Neue Folge |volume=22 |pages=1–79 |language=German ] 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 either pertain to "Carcharodontosaurus"cite journal |last=Sereno |first=P.C. |authorlink=Paul Sereno |coauthors=Beck, A.L.; Dutheil, D.B.; Gado, B.; Larsson, H.C.E.; Lyon, G.H.; Marcot, J.D.; Rauhut, O.W.M.; Sadleir, R.W.; Sidor, C.A.; Varricchio, D.D.; Wilson, G.P; and Wilson, J.A. |year=1998 |title=A long-snouted predatory dinosaur from Africa and the evolution of spinosaurids |journal=Science |volume=282 |pages=1298–1302 |doi=10.1126/science.282.5392.1298 |pmid=9812890 ] or to "Sigilmassasaurus".cite journal |last=Russell |first=D.A. |authorlink=Dale Russell |year=1996 |title=Isolated dinosaur bones from the Middle Cretaceous of the Tafilalt, Morocco |journal=Bulletin du Muséum National d'Histoire Naturelle, Paris, 4e série, section C |volume=18 |issue=2-3 |pages=349–402] Some of the "Spinosaurus" fossils were damaged during transport back to the Deutsches Museum, in Munich, Germany, and the remaining bones were completely lost due to Allied bombing in 1944.

Two species of "Spinosaurus" have been named: "Spinosaurus aegyptiacus" (meaning "Egyptian spine lizard") and "Spinosaurus marocannus" (meaning "Moroccan spine lizard"). "S. marocannus" was originally described by Dale Russell as a new species based on the length of its neck vertebrae. Later authors have been split on this topic, some considering the length of the vertebrae to be variable from individual to individual and therefore regarding "S. marocannus" as invalid or a synonym of "S. aegyptiacus",cite web| last =Mortimer| first =M.| title =Megalosauroidea| work =The Theropod Database| publisher =University of Washington| date =2004| url =http://home.comcast.net/~eoraptor/Megalosauroidea.htm#Spinosaurusaegyptiacus| accessdate =2008-08-14] and others retaining it as valid.

pecimens

Six partial specimens of "Spinosaurus" have been described. The probable size of these individual spinosaurs can be estimated using comparison to known material from other spinosaurid dinosaurs. The estimates below are based on the [http://home.comcast.net/~eoraptor/Megalosauroidea.htm#Spinosaurusaegyptiacus Theropod Database] and Dal Sasso "et al", 2005.

IPHG 1912 VIII 19, described by Stromer in 1915, was the holotype. This specimen, from a subadult individual, was destroyed in World War II. However, detailed drawings and descriptions of the specimen remain. The individual is estimated to have been around m to ft |14|abbr=mos long and to have weighed about 6.7 tonnes (7.4 tons). The material consisted of a maxilla (upper jaw) fragment, an incomplete dentary (lower jaw) measuring 750 millimeters (29.5 in) long, (the skull is estimated to have been m to ft |1.45|abbr=mos long with a mandible approximately m to ft |1.34|abbr=mos long), nineteen teeth, two incomplete cervical vertebrae, seven back vertebrae, dorsal ribs, gastralia, and eight caudal centra. This was the specimen that Rauhut thought was chimeric. CMN 50791, described by Russell in 1996, is the holotype of "Spinosaurus marocannus". The material it is based on includes a mid-cervical vertebra which is 195 millimeters (7.68 in) long, an anterior dorsal neural arch, an anterior dentary, and a mid-dentary. MNHN SAM 124, described by Taquet and Russell in 1998, consists of partial premaxillae, partial maxillae, vomers, and a dentary fragment. They came from an individual estimated to have been about m to ft |14|abbr=mos long and to have weighed about 6.7 tonnes (7.38 tons). The skull is estimated at approximately m to ft |1.42|abbr=mos long. Office National des Mines nBM231, described by Buffetaut and Ouaja in 2002, consists of an anterior dentary from Tunisia which is very similar to existing material of "S. aegyptiacus".Buffetaut, E & Ouaja, M (2002) A new specimen of "Spinosaurus" (Dinosauria, Theropoda) from the Lower Cretaceous of Tunisia, with remarks on the evolutionary history of the Spinosauridae. "Bulletin de la Société Géologique de France" 173: 415–421. DOI|10.2113/173.5.415] MSNM V4047, described by Cristiano Dal Sasso of the Civic Natural History Museum in Milan and his colleagues in 2005, consists of premaxillae, partial maxillae, and partial nasals, which together measure 988 millimeters (3.24 ft) long. The massive skull is estimated at m to ft |1.75|abbr=mos long, and the entire animal is estimated to have been around 16 to 18 meters (52 to 59 ft) in length and weighed around 7 to 9 tonnes (7.7 to 9.9 tons). UCPC-2, also described by Dal Sasso "et al." in 2005, consists of a 'fluted crest' from the region in front of the eyes.

Paleoecology

The environment inhabited by "Spinosaurus" is only partially understood, and covers a great deal of what is now northern Africa. Those "Spinosaurus" that lived in what is now Egypt, for example, may have contended with shoreline conditions on tidal flats and channels, living in mangrove forests alongside similarly large dinosaurian predators "Bahariasaurus" and "Carcharodontosaurus", giant titanosaur sauropod "Paralititan", smaller titanosaur "Aegyptosaurus", 10 meter (33 ft) long crocodilian "Stomatosuchus", and the coelacanth "Mawsonia".cite journal |last=Smith |first=J.B. |coauthors=Lamanna, M.C.; Lacovara, K.J.; Dodson, P.; Smith, J.R.; Poole, J.C.; Giegengack, R.; and Attia, Y. |year=2001 |title=A Giant sauropod dinosaur from an Upper Cretaceous mangrove deposit in Egypt |journal=Science |volume=292 |issue=5522 |pages=1704–1706 |doi=10.1126/science.1060561 |pmid=11387472]

Feeding ecology

It is unclear whether "Spinosaurus" was primarily a terrestrial predator or a fisher, as indicated by its elongated jaws, conical teeth and raised nostrils. The only direct evidence for spinosaur diet comes from related European and South American taxa. "Baryonyx" was found with both fish scales and bones from juvenile "Iguanodon" in its stomach, while a tooth embedded in a South American pterosaur bone suggests that spinosaurs occasionally preyed on these flying archosaurs. [cite journal |last=Buffetaut |first=E. |coauthors=Martill, D.; and Escuillié, F. |year=2004 |title=Pterosaurs as part of a spinosaur diet |journal=Nature |volume=430 |pages=33 |doi=10.1038/430033a] "Spinosaurus" was likely to have been a generalized and opportunistic predator, possibly a Cretaceous equivalent of large grizzly bears, being biased toward fishing, though it undoubtedly scavenged and took many kinds of small or medium-sized prey.cite book |last=Paul |first=Gregory S. |authorlink=Gregory S. Paul |title=Predatory Dinosaurs of the World |year=1988 |publisher=Simon & Schuster |location=New York |isbn=0-671-61946-2 |chapter=Family Spinosauridae |pages=271–274 ]

Paleobiology

ize

Since its discovery, "Spinosaurus" has been a top contender for longest and largest theropod dinosaur, though this fact did not reach the public consciousness until its depiction in the film "Jurassic Park III" and the description of a new specimen in 2005. Both Friedrich von Huenecite journal |last=von Huene |first=F.R. |year=1926 |title=The carnivorous saurischia in the Jura and Cretaceous formations principally in Europe
journal=Rev. Mus. La Plata |volume=29 |pages=35–167
] and Donald F. Glut,cite book |last=Glut |first=D.F. |year=1982 |title=The New Dinosaur Dictionary |publisher=Citadel Press |location=Secaucus, NJ |pages=226–228 |isbn=0-8065-0782-9] decades apart, listed it as among the most massive theropods or the most massive in their surveys, at upwards of 6 tons in weight and m to ft |15|abbr=mos in length. In 1988, Gregory S. Paul also listed it as the longest theropod at m to ft |15|abbr=mos, but gave a lower mass estimate.Paul, G.S. (1988). "Predatory Dinosaurs of the World." New York: Simon and Schuster. 464 pp.] More recent estimates, based on new specimens, list "Spinosaurus" at 16 to 18 metres (53.3 to 60 feet) long and 7 to 9 tonnes in weight (7.7 to 9.9 tons).

François Therrien and Donald Henderson, in a 2007 paper using scaling based on skull length, challenged previous estimates, finding the length too great and the weight too small. Their estimates include a length of 12.6 to 14.3 meters (41.3 to 47.0 ft) and a mass of 12.0 to 20.9 tonnes (13.2 to 23.0 tons).cite journal |last=Therrien |first=F. |coauthors= and Henderson, D.M. |year=2007 |title=My theropod is bigger than yours...or not: estimating body size from skull length in theropods |journal=Journal of Vertebrate Paleontology |volume=27 |issue=1 |pages=108–115 |doi=10.1671/0272-4634(2007)27 [108:MTIBTY] 2.0.CO;2] Their study has been criticized for the choice of large theropods used for comparison (most of the skeletons of large theropods used to set the initial equations are of tyrannosaurids and carnosaurs, which have a different build than spinosaurids) and for issues relating to their spinosaurid skull reconstructions.cite web |url=http://dml.cmnh.org/2007Mar/msg00292.html |title=Comments on Therrien and Henderson's new paper |accessdate=2007-07-04 |last=Mortimer |first=Mickey |date=2007-03-25 |publisher=Dinosaur Mailing List] Resolution awaits more complete remains.

ail

"Spinosaurus" sails were unusual, although other dinosaurs of the same time and area, namely the ornithopod "Ouranosaurus" and the sauropod "Rebbachisaurus," might have developed a similar structural adaptation of their dorsal vertebrae (however, this is not uncontroversial; see the articles about these animals for more information). The sail is possibly analogous (not homologous) to that of the Permian mammal-like reptile, "Dimetrodon", which lived before the dinosaurs even appeared; these similarities are due to parallel evolution. The sail may also have been more hump-like than sail-like; as noted by Jack Bowman Bailey most recently, spinosaur spines are not thin rods but broad front to back, rather like those of some types of buffalo, and so may have supported a thicker, fatty structure as opposed to a skin sail.cite journal |last=Bailey |first=Jack Bowman |year=1997 |title=Neural spine elongation in dinosaurs: sailbacks or buffalo-backs? |journal=Journal of Paleontology |volume=71 |issue=6 |pages=1124–1146]

The function of these sails is uncertain; scientists have proposed several hypotheses including heat regulation and display. In addition, such a prominent feature on its back could also make it appear even larger than it was, intimidating other animals.

If the sail contained abundant blood vessels, the animal could have used the sail's large surface area to absorb heat. This would imply that the animal was only partly warm-blooded at best and lived in climates where nighttime temperatures were cool or low and the sky usually not cloudy. It is thought that "Spinosaurus" and "Ouranosaurus" both lived in or at the margins of an earlier version of the Sahara Desert, which could explain this. It is also possible that the sail was used to radiate excess heat from the body, rather than to collect it. Large animals, due to the relatively small ratio of surface area of their body compared to the overall volume (Haldane's principle), face far greater problems of dissipating excess heat at higher temperatures than gaining it at lower. Sails of these dinosaurs added considerably to the skin area of the body, with minimum increase of volume. Furthermore, if the sail was turned away from the sun, or positioned at a 90 degree angle towards a cooling wind, the animal would quite effectively cool itself in the warm climate of Cretaceous Africa.cite book |last=Halstead |first=L.B. |year=1975 |title=The Evolution and Ecology of the Dinosaurs |publisher=Peter Lowe |location=London |pages=1–116 |isbn=0856540188 ]

Elaborate body structures of many modern-day animals usually serve to attract members of the opposite sex during mating. It is quite possible that the sails of these dinosaurs were used for courtship, in a way similar to a peacock's tail. Stromer speculated that males and females may have differed in the size of the neural spine. If this was the case, the sails may have been brightly colored, but this is purely speculative.

Finally, it is quite possible that the sail combined these functions, acting normally as a heat regulator, becoming a courting aid during the mating season, being used to cool itself and, on occasions, turning into an intimidating device when an animal was feeling threatened.

Posture

Although traditionally depicted as a biped, it has been suggested since the early 1980s that "Spinosaurus" was at least an occasional quadruped. This has been bolstered by the discovery of "Baryonyx", a relative with robust arms.cite book |last=Glut |first=Donald F. |authorlink=Donald F. Glut |title=Dinosaurs: The Encyclopedia. 1st Supplement |year=2000 |publisher=McFarland & Company, Inc. |location=Jefferson, North Carolina |isbn=0-7864-0591-0 |pages=329–333 |chapter=Spinosaurus] Bailey (1997) was sympathetic to a possible quadrupedal posture, leading to new restorations of it as such. This hypothesis has fallen out of favor, at least as a typical gait, though spinosaurids may have crouched in a quadrupedal posture.cite journal |last=Charig |first=Alan J. |coauthors=and Milner, Angela C. |year=1997 |title="Baryonyx walkeri", a fish-eating dinosaur from the Wealden of Surrey |journal=Bulletin of the Natural History Museum, Geology Series |volume=53 |issue=1 |pages=11–70]

In popular culture

"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, 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.

"Spinosaurus" was the main antagonist in the 2001 film "Jurassic Park III". It was portrayed as larger and more powerful than "Tyrannosaurus": in a scene depicting a battle between the two resurrected predators, "Spinosaurus" emerges victorious by snapping the tyrannosaur's neck. In reality, such a battle could never have taken place while the species were extant, since "Spinosaurus" and "Tyrannosaurus" lived thousands of kilometres and millions of years apart. After appearing in "Jurassic Park III", "Spinosaurus" was featured in a wide variety of merchandise related to the "Jurassic Park" films, including a number of video games such as "" from Vivendi Universal.

References

External links

* [http://www.nhm.ac.uk/jdsml/nature-online/dino-directory/detail.dsml?Genus=Spinosaurus "Spinosaurus" in the Dino Directory]
* [http://www.dinodata.org/index.php?option=com_content&task=view&id=7422&Itemid=67 "Spinosaurus" at DinoData]
* [http://www.livescience.com/animalworld/060301_big_carnivores.html The Biggest Carnivore: Dinosaur History Rewritten]
* [http://piclib.nhm.ac.uk/piclib/webimages/0/37000/0/37012_big.jpg"Spinosaurus" Jaws]
* [http://discovermagazine.com/2007/jan/paleontology/article_view?b_start:int=1&-C= Discover Magazine]


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Spinosaurus — Skelettrekonstruktion von Spinosaurus aegyptiacus Zeitraum Unter bis Oberkreide (Albium–Cenomanium) 106 bis 93,5 Mio. Jahre Fundorte …   Deutsch Wikipedia

  • Spinosaurus — Spinosaurus …   Wikipédia en Français

  • Spinosaurus — Spinosaurus …   Wikipédia en Français

  • Spinosaurus —   Spinosaurus Rango temporal: Cretácico superior …   Wikipedia Español

  • Spinosaurus — ? † Спинозавр Научная классификация Царство: Животные Тип: Хордовые Класс …   Википедия

  • Spinosaurus — El Espinosauro o spinosaurus fue un terópodo encontrado en Níger y en Egipto, que desarrolló largas espinas dorsales, las cuales habrían sostenido una gran vela de piel y podían llegar a medir 1 80 metros. Esta vela pudo actuar calentando la… …   Enciclopedia Universal

  • Spinosaurus aegyptiacus — Spinosaurus Spinosaurus …   Wikipédia en Français

  • Spinosaurus aegyptiacus —   Spinosaurus aegyptiacus Rango temporal: Cretácico superior …   Wikipedia Español

  • spinosaurus — noun A large, fierce, extinct, carnivorous dinosaur with a long snout like that of a crocodile and with a sail on its back …   Wiktionary

  • Spinosaure — Spinosaurus Spinosaurus …   Wikipédia en Français

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”