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Spinosaurids
Temporal range: Late Jurassic – Upper Cretaceous
Skeleton of Spinosaurus in a swimming pose
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Sauropsida
Superorder:
Dinosauria
Order:
Saurischia
Suborder:
Theropoda
Superfamily:
Megalosauroidea
Family:
Spinosauridae

Stromer, 1915
Subgroups

Spinosauridae (meaning 'spined lizards') is a family of carnivorous theropod dinosaurs, it is named after Spinosaurus, one of the largest known land predators, which could have reached up to 15 m (49 ft) in length.[1] Spinosaurids are unique among other meat-eating dinosaurs from their more water-based lifestyle, which involved a diet of mostly fish. Most spinosaurids lived during the Cretaceous periodand their fossils have been found all over the world, including Asia, South America, Europe, Africa, and Australia.

Description[change | change source]

Size comparison of Spinosaurus, Suchomimus, Baryonyx, and Irritator with a human

Anatomy[change | change source]

Spinosaurids had bigger arms than most theropods, the claw on the first finger was usually the largest. They evolved jaws like those of crocodiles,and their teeth were long and cone-shaped, made to trap prey in their mouths instead of tearing them apart. Because of this, their teeth usually did not have the strong knife-like edges (called serrations) of a lot of other meat-eating dinosaurs.[2][3]

Dorsal Sails[change | change source]

Spinosaurus aegyptiacus, the first spinosaurid discovered, is known for its unusually tall backbones (or vertebra), some over a meter tall. rebuilt as a sail or hump running down its back.[4] Paleontologists have compared this to the dorsal fin of a sailfish.[5]

Hip regions of three spinosaurids, note the varying shapes of their sails

Ichthyovenator's sail is half a meter tall and split into two at the hips.[6] Suchomimus also has a low, ridge-like sail, smaller than that of Spinosaurus.[4] Baryonyx, however, didn't have a sail.[7] Other spinosaurids such as Irritator, might've also had sails, but more complete fossils are needed to know for sure.

Paleontologists have proposed many theories about what spinosaurids might have used their sails for, these include things like regulating their body temperature in a process called thermoregulation,[8] to help them swim,[9] to store energy or insulate the animal,[10] or they could have used them as a display to either scare off predators, or attract mates.[11][12]

Bony crests[change | change source]

Another reason why the skulls of spinosaurids are very different from those of other theropods is that they often feature big or small crests formed from their nasal bones. Spinosaurus's crest is shaped like a ridge, and Suchomimus and Baryonyx have them as tiny bumps on the tops of their skulls.[13] Irritator and Cristatusaurus also have crests, although they are much smaller.[14][15]

History[change | change source]

Timespan[change | change source]

Suchomimus and Baryonyx to scale

The spinosaurids might have existed as early as the Late Jurassic, through teeth found in Tanzania that belonged to Ostafrikasaurus.[16] Baryonychines were common, as represented by Baryonyx, which lived during the Barremian of England and Spain. Baryonyx-like teeth are found from the earlier Hauterivian and later Aptian sediments of Spain, as well as the Hauterivian of England, and the Aptian of Niger. The earliest record of spinosaurines is from Africa; they are present in Albian sediments of Tunisia and Algeria, and in Cenomanian sediments of Egypt and Morocco. Spinosaurines are also found in Hauterivian and Aptian-Albian sediments of Thailand, and Southern China. In Africa, baronychines were common in the Aptian, and then replaced by spinosaurines in the Albian and Cenomanian.[17]

Some intermediate specimens extend the known range of spinosaurids past the youngest dates of named taxa. A single baryonychine tooth was found from the mid-Santonian, in the Majiacun Formation of Henan, China.[18] Possible spinosaur remains were also reported from the late Maastrichtian Maevarano Formation.[19]

Locations[change | change source]

Map showing places where spinosaurid fossils have been found

Confirmed spinosaurids have been found on every continent except North America and Antarctica. The first was discovered in 1912 in Egypt and named in 1915 as Spinosaurus aegyptiacus.[20] Over the years Africa has shown the most spinosaurid discoveries,[21][17] fossils found at the Kem Kem formation in Morocco show that North Africa had an ecosystem full of many huge coexisting predators, including dinosaurs and large crocodilians.[22][23]

Fossil neck bones of the Australian Spinosaurid, the one on the bottom right is of Baryonyx for comparison.[24]

They've also been found in Brazil, South America with the discoveries of Irritator, Angaturama, and Oxalaia.[25][26] There was also a fossil tooth in Argentina which has been referred to spinosauridae by Salgado et al.[27] This referral is doubted by Tanaka,[28] who offers Hamadasuchus, a crocodilian, as the most likely animal of origin for these teeth.

Baryonychines have been discovered on not only in Africa, with Suchomimus,[17][29] but also in Europe, as Baryonyx and Suchosaurus.[30] Baryonyx-like teeth are also reported from the Ashdown Sands of Sussex, in England, and the Burgos Province, in Spain. A partial skeleton and many fossil teeth also hint at the possibility of spinosaurids being widespread in Asia. So far, three have been named, Ichthyovenator; a baryonychine,[31] and Siamosaurus and "Sinopliosaurus" fusuiensis; two indeterminate spinosaurids.[17][18] At la Cantalera-1, a site in the Early Barremanian Blesa Formation in Treul, Spain, two types of spinosaurid teeth were found, and they were assigned, tentatively, as indeterminate spinosaurine and baryonychine taxa.[32]

An intermediate spinosaurid was discovered in the Early Cretaceous Eumeralla Formation, Australia.[33] It is known from a single 4 cm long partial cervical vertebra, designated P221081. It is missing most of the neural arch. The specimen is from a juvenile estimated to be about 2 to 3 meters long (6-9 ft). Out of all spinosaurs it most closely resembles Baryonyx.[34]

Paleobiology[change | change source]

A study made in 2010 by Roman Amiot and his colleagues found that spinosaurids had very semiaquatic (living partly in water, and partly on land) lifestyles, this means they lived in habitats like those of hippopotamuses, crocodiles, and turtles, making them very unusual compared to other theropods. It also means they could exist at the same time and place as other large predators without competing for food. For example; Carcharodontosaurus, which lived at the same time as Sigilmassasaurus and Spinosaurus, did not need to fight with either of those animals for prey; those spinosaurids ate fish, while Carcharodontosaurus was on land most of the time, hunting smaller dinosaurs.[35]

Classification[change | change source]

The family "Spinosauridae" was named by the German paleontologist Ernst Stromer in 1915, he was the one that discovered the first genus in the group, Spinosaurus. And as scientists discovered more fossils of its close relatives, the family was eventually split into two subfamilies: Baryonychinae, and Spinosaurinae. This was done because of differences in the anatomy of their skulls and teeth.

Spinosaurus aegyptiacus, the largest meat-eating dinosaur
Skeletons of Suchomimus and Baryonyx

This is a cladogram made in 2017 showing the relationships between different spinosaurids inside of megalosauroidea.[36]

Megalosauroidea


Condorraptor



Marshosaurus



Piatnitzkysaurus





Afrovenator



Dubreuillosaurus



Duriavenator



Eustreptospondylus



Leshansaurus



Magnosaurus



Megalosaurus



Piveteausaurus



Torvosaurus




Baryonyx



Cristatusaurus



Suchomimus




Angaturama




Oxalaia



MSNM V4047 (referred to Spinosaurus)








References[change | change source]

  1. ↑ Ibrahim, Nizar; Sereno, Paul C.; Dal Sasso, Cristiano; Maganuco, Simone; Fabri, Matteo; Martill, David M.; Zouhri, Samir; Myhrvold, Nathan; Lurino, Dawid A. (2014). "Semiaquatic adaptations in a giant predatory dinosaur". Science. 345 (6204): 1613–6. Bibcode:2014Sci...345.1613I. doi:10.1126/science.1258750. PMID 25213375. Supplementary Information
  2. ↑ Sereno, Paul C., Allison L. Beck, Didier B. Dutheil, Boubacar Gado, Hans C. E. Larsson, Gabrielle H. Lyon, Jonathan D. Marcot, et al. 1998. “A Long-Snouted Predatory Dinosaur from Africa and the Evolution of Spinosaurids.” Science 282 (5392): 1298–1302. doi:10.1126/science.282.5392.1298.
  3. ↑ Rayfield, Emily J. 2011. “Structural Performance of Tetanuran Theropod Skulls, with Emphasis on the Megalosauridae, Spinosauridae and Carcharodontosauridae.” Special Papers in Palaeontology 86 (November). https://www.researchgate.net/publication/250916680_Structural_performance_of_tetanuran_theropod_skulls_with_emphasis_on_the_Megalosauridae_Spinosauridae_and_Carcharodontosauridae.
  4. ↑ 4.0 4.1 Hecht, Jeff. 1998. “Fish Swam in Fear.” New Scientist. November 21. https://www.newscientist.com/article/mg16021610-300-fish-swam-in-fear/.
  5. ↑ "Gimsa, J., Sleigh, R., Gimsa, U., (2015) : "The riddle of Spinosaurus aegyptiacus ' dorsal sail". University of Rostock, Chair for Biophysics, Gertrudenstr. 11A, 18057 Rostock, Germany". {{cite journal}}: Cite journal requires |journal= (help)
  6. ↑ Allain, R.; Xaisanavong, T.; Richir, P.; Khentavong, B. (2012). "The first definitive Asian spinosaurid (Dinosauria: Theropoda) from the early cretaceous of Laos". Naturwissenschaften. 99 (5): 369–377. Bibcode:2012NW.....99..369A. doi:10.1007/s00114-012-0911-7. PMID 22528021.
  7. ↑ Charig, A. J.; Milner, A. C. (1997). "Baryonyx walkeri, a fish-eating dinosaur from the Wealden of Surrey". Bulletin of the Natural History Museum of London. 53: 11–70.
  8. ↑ Halstead, L.B. (1975). The Evolution and Ecology of the Dinosaurs. London: Eurobook Limited. pp. 1–116. ISBN 0-85654-018-8.
  9. ↑ "Gimsa, J., Sleigh, R., Gimsa, U., (2015) : "The riddle of Spinosaurus aegyptiacus ' dorsal sail". University of Rostock, Chair for Biophysics, Gertrudenstr. 11A, 18057 Rostock, Germany". {{cite journal}}: Cite journal requires |journal= (help)
  10. ↑ Bailey, J.B. (1997). "Neural spine elongation in dinosaurs: sailbacks or buffalo-backs?". Journal of Paleontology. 71 (6): 1124–1146. JSTOR 1306608.
  11. ↑ Bailey, J.B. (1997). "Neural spine elongation in dinosaurs: sailbacks or buffalo-backs?". Journal of Paleontology. 71 (6): 1124–1146. JSTOR 1306608.
  12. ↑ Stromer, E. (1915). "Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltier-Reste der Baharije-Stufe (unterstes Cenoman). 3. Das Original des Theropoden Spinosaurus aegyptiacus nov. gen., nov. spec". Abhandlungen der Königlich Bayerischen Akademie der Wissenschaften, Mathematisch-physikalische Klasse (in German). 28 (3): 1–32.[permanent dead link]
  13. ↑ Charig, A. J.; Milner, A. C. (1997). "Baryonyx walkeri, a fish-eating dinosaur from the Wealden of Surrey". Bulletin of the Natural History Museum of London. 53: 11–70.
  14. ↑ Sues, H. D.; Frey, E.; Martill, D. M.; Scott, D. M. (2002). "Irritator challengeri, a spinosaurid (Dinosauria: Theropoda) from the Lower Cretaceous of Brazil". Journal of Vertebrate Paleontology. 22 (3): 535–547. doi:10.1671/0272-4634(2002)022[0535:ICASDT]2.0.CO;2.
  15. ↑ Taquet, P. and Russell, D.A. (1998). "New data on spinosaurid dinosaurs from the Early Cretaceous of the Sahara". Comptes Rendus de l'Académie des Sciences à Paris, Sciences de la Terre et des Planètes 327: 347-353
  16. ↑ Buffetaut, Eric. 2008. “Spinosaurid Teeth from the Late Jurassic of Tendaguru, Tanzania, with Remarks on the Evolutionary and Biogeographical History of the Spinosauridae.” https://www.academia.edu/3101178/Spinosaurid_teeth_from_the_Late_Jurassic_of_Tendaguru_Tanzania_with_remarks_on_the_evolutionary_and_biogeographical_history_of_the_Spinosauridae
  17. ↑ 17.0 17.1 17.2 17.3 Buffetaut, Eric, and Mohamed Ouaja. 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 (5): 415–21. doi:10.2113/173.5.415.
  18. ↑ 18.0 18.1 Hone, Dave, Xing Xu, Deyou Wang, and Vertebrata PalAsiatica. 2010. “A Probable Baryonychine (Theropoda: Spinosauridae) Tooth from the Upper Cretaceous of Henan Province, China (PDF Download Available).” ResearchGate. January. https://www.researchgate.net/publication/271967379_A_probable_Baryonychine_Theropoda_Spinosauridae_tooth_from_the_Upper_Cretaceous_of_Henan_Province_China.
  19. ↑ Weishampel, David B.; Barrett, Paul M.; Coria, Rodolfo A.; Le Loueff, Jean; Xu Xing; Zhao Xijin; Sahni, Ashok; Gomani, Elizabeth M. P.; Noto, Christopher N. (2004). "Dinosaur distribution". In Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. p. 624. ISBN 0-520-24209-2.
  20. ↑ Stromer, E. (1915). "Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltier-Reste der Baharije-Stufe (unterstes Cenoman). 3. Das Original des Theropoden Spinosaurus aegyptiacus nov. gen., nov. spec". Abhandlungen der Königlich Bayerischen Akademie der Wissenschaften, Mathematisch-physikalische Klasse (in German). 28 (3): 1–32.[permanent dead link]
  21. ↑ Benyoucef, Madani, Emilie Läng, Lionel Cavin, Kaddour Mebarki, Mohammed Adaci, and Mustapha Bensalah. 2015. “Overabundance of Piscivorous Dinosaurs (Theropoda: Spinosauridae) in the Mid-Cretaceous of North Africa: The Algerian Dilemma.” Cretaceous Research 55 (July): 44–55. doi:10.1016/j.cretres.2015.02.002.
  22. ↑ Hendrickx, Christophe, Octávio Mateus, and Eric Buffetaut. 2016. “Morphofunctional Analysis of the Quadrate of Spinosauridae (Dinosauria: Theropoda) and the Presence of Spinosaurus and a Second Spinosaurine Taxon in the Cenomanian of North Africa.” PLOS ONE 11 (1): e0144695. doi:10.1371/journal.pone.0144695.
  23. ↑ Amiot, R.; Buffetaut, E.; Lécuyer, C.; Wang, X.; Boudad, L.; Ding, Z.; Fourel, F.; Hutt, S.; Martineau, F.; Medeiros, A.; Mo, J.; Simon, L.; Suteethorn, V.; Sweetman, S.; Tong, H.; Zhang, F.; Zhou, Z. (2010). "Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods". Geology. 38 (2): 139–142. Bibcode:2010Geo....38..139A. doi:10.1130/G30402.1.
  24. ↑ Farke, Andrew A.; Benson, Roger B. J.; Rich, Thomas H.; Vickers-Rich, Patricia; Hall, Mike (2012). "Theropod Fauna from Southern Australia Indicates High Polar Diversity and Climate-Driven Dinosaur Provinciality". PLoS ONE. 7 (5): e37122. doi:10.1371/journal.pone.0037122. ISSN 1932-6203.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  25. ↑ Buffetaut, Eric, David Martill, and François Escuillié. 2004. “Pterosaurs as Part of a Spinosaur Diet.” Nature 430. doi:10.1038/430033a.
  26. ↑ Kellner, Alexander W.A.; Sergio A.K. Azevedeo; Elaine B. Machado; Luciana B. Carvalho; Deise D.R. Henriques (2011). "A new dinosaur (Theropoda, Spinosauridae) from the Cretaceous (Cenomanian) Alcântara Formation, Cajual Island, Brazil" (PDF). Anais da Academia Brasileira de Ciências. 83 (1): 99–108. doi:10.1590/S0001-37652011000100006. ISSN 0001-3765.
  27. ↑ Salgado, Leonardo, José I. Canudo, Alberto C. Garrido, José I. Ruiz-Omeñaca, Rodolfo A. García, Marcelo S. de la Fuente, José L. Barco, and Raúl Bollati. 2009. “Upper Cretaceous Vertebrates from El Anfiteatro Area, Río Negro, Patagonia, Argentina.” Cretaceous Research 30 (3): 767–84. doi:10.1016/j.cretres.2009.01.001.
  28. ↑ Tanaka, Gengo. 2017. “Fine Sculptures on a Tooth of Spinosaurus (Dinosauria, Theropoda) from Morocco.” Bulletin of Gunma …. Accessed May 30. https://www.academia.edu/1300482/Fine_sculptures_on_a_tooth_of_Spinosaurus_Dinosauria_Theropoda_from_Morocco.
  29. ↑ Sereno, P.C.; 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; Wilson, J.A. (1998). "A long-snouted predatory dinosaur from Africa and the evolution of spinosaurids". Science. 282 (5392): 1298–1302. Bibcode:1998Sci...282.1298S. doi:10.1126/science.282.5392.1298. PMID 9812890. Retrieved 2013-03-19.
  30. ↑ Mateus, O.; Araújo, R.; Natário, C.; Castanhinha, R. (2011). "A new specimen of the theropod dinosaur Baryonyx from the early Cretaceous of Portugal and taxonomic validity of Suchosaurus" (PDF). Zootaxa. 2827: 54–68.
  31. ↑ Allain, R.; Xaisanavong, T.; Richir, P.; Khentavong, B. (2012). "The first definitive Asian spinosaurid (Dinosauria: Theropoda) from the early cretaceous of Laos". Naturwissenschaften. 99 (5): 369–377. Bibcode:2012NW.....99..369A. doi:10.1007/s00114-012-0911-7. PMID 22528021.
  32. ↑ Alonso, Antonio, and José Ignacio Canudo. 2016. “On the Spinosaurid Theropod Teeth from the Early Barremian (Early Cretaceous) Blesa Formation (Spain).” Historical Biology 28 (6): 823–34. doi:10.1080/08912963.2015.1036751.
  33. ↑ "Australian 'Spinosaur' unearthed". Australian Geographic. Retrieved 2018-04-15.
  34. ↑ Barrett, P. M.; Benson, R. B. J.; Rich, T. H.; Vickers-Rich, P. (2011). "First spinosaurid dinosaur from Australia and the cosmopolitanism of Cretaceous dinosaur faunas". Biology Letters. 7 (6): 933–936. doi:10.1098/rsbl.2011.0466. ISSN 1744-9561.
  35. ↑ Amiot, R.; Buffetaut, E.; Lécuyer, C.; Wang, X.; Boudad, L.; Ding, Z.; Fourel, F.; Hutt, S.; Martineau, F.; Medeiros, A.; Mo, J.; Simon, L.; Suteethorn, V.; Sweetman, S.; Tong, H.; Zhang, F.; Zhou, Z. (2010). "Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods". Geology. 38 (2): 139–142. Bibcode:2010Geo....38..139A. doi:10.1130/G30402.1.
  36. ↑ Sales, M.A.F.; Schultz, C.L. (2017). "Spinosaur taxonomy and evolution of craniodental features: Evidence from Brazil". PLoS ONE. 12 (11): e0187070. doi:10.1371/journal.pone.0187070.{{cite journal}}: CS1 maint: unflagged free DOI (link)

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