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{{Automatic taxobox
| name = Spinosaurids
| fossil_range = [[Early Cretaceous]]–[[Late Cretaceous]], {{fossil range|earliest=152.1|139|93|latest=
| image = Spinosauridae Diversity.jpg
| image_upright = 1.1
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| taxon = Spinosauridae
| authority = [[Ernst Stromer|Stromer]], [[1915 in paleontology|1915]]
| type_species = {{extinct}}''[[Spinosaurus|Spinosaurus aegyptiacus]]''
| type_species_authority = Stromer, 1915
| subdivision_ranks = Subgroups
| subdivision = *{{extinct}}''[[
*{{extinct}}''[[Monolophosaurus]]''?<ref>[[Rauhut, Oliver W M; Bakirov, Aizek A; Wings, Oliver; Fernandes, Alexandra E; Hübner, Tom R (2024-08-01). "A new theropod dinosaur from the Callovian Balabansai Formation of Kyrgyzstan". Zoological Journal of the Linnean Society. 201 (4). doi:10.1093/zoolinnean/zlae090. ISSN 0024-4082.]]</ref>
*{{extinct}}''[[Cristatusaurus]]''▼
*{{extinct}}''[[Datanglong]]''?<ref name=Cau>{{Cite journal|last=Cau |first=A. |title=A Unified Framework for Predatory Dinosaur Macroevolution |year=2024 |journal=Bollettino della Società Paleontologica Italiana |volume=63 |issue=1 |doi=10.4435/BSPI.2024.08 |doi-broken-date=2024-11-20 |url=https://www.researchgate.net/publication/379902868 }} [https://www.paleoitalia.it/bollettino-spi/bspi-vol-631/ Supplementary Material]</ref>
*{{extinct}}''[[Iberospinus]]''
*{{extinct}}''[[Ostafrikasaurus]]''?
* {{extinct}}'''[[
**{{extinct}}''[[Vallibonavenatrix]]''
**{{extinct}}''[[Baryonyx]]''
▲**{{extinct}}''[[Cristatusaurus]]''?
**{{extinct}}''[[Protathlitis]]''
**{{extinct}}''[[Riojavenatrix]]''
**{{extinct}}''[[Suchosaurus]]''
**{{extinct}}'''Ceratosuchopsini'''
***{{extinct}}''[[Ceratosuchops]]''
***{{extinct}}''[[Riparovenator]]''
***{{extinct}}''[[Suchomimus]]''
*†'''Spinosaurinae'''
**{{extinct}}''[[Ichthyovenator]]''
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* Irritatoridae <small>[[David Martill|Martill]] ''et al.'', 1996</small>
* Sigilmassasauridae <small>Russell, 1996</small>
}}
Spinosaurids were large [[Bipedalism|bipedal]] [[carnivore]]s. Their [[crocodilia]]n-like skulls were long, low and narrow, bearing conical teeth with reduced or absent [[Glossary of dinosaur anatomy#serrations|serrations]]. The tips of their upper and [[Glossary of dinosaur anatomy#mandible|lower jaws]] fanned out into a spoon-shaped structure similar to a [[Rosette (design)|rosette]], behind which there was a [[Glossary of dinosaur anatomy#subnarial gap|notch]] in the upper jaw that the expanded tip of the lower jaw fit into. The [[Glossary of dinosaur anatomy#bony nostrils|nostrils]] of spinosaurids were retracted to a position further back on the head than in most other theropods, and they had bony crests on their heads along the midline of their skulls. Their robust shoulders wielded stocky forelimbs, with three-fingered hands that bore an enlarged [[Glossary of dinosaur anatomy#unguals|claw]] on the first [[Glossary of dinosaur anatomy#digit|digit]]. In many [[species]], the upwards-projecting [[Glossary of dinosaur anatomy#neural spine|neural spines]] of the [[Glossary of dinosaur anatomy#vertebrae|vertebrae]] (backbones) were significantly elongated and formed a [[Neural spine sail|sail]] on the animal's back (hence the family's etymology), which supported either a layer of skin or a fatty hump.
The genus ''[[Spinosaurus]]'', from which the family, one of its [[subfamily|subfamilies]] (Spinosaurinae) and [[Tribe (biology)|tribes]] (Spinosaurini) borrow their names, is the longest known terrestrial [[Predation|predator]] from the fossil record, with an estimated length of up to {{Convert|14|m|sp=us}} and body mass of up to {{convert|7.4|MT|ST}} (similar to the weight of an [[African elephant]]). The closely related genus ''[[Sigilmassasaurus]]'' may have reached a similar or greater size, though its [[Taxonomy (biology)|taxonomy]] is disputed. Direct fossil evidence and anatomical [[adaptation]]s indicate that spinosaurids were at least partially [[piscivorous]] (fish-eating), with additional fossil finds indicating they also fed on other dinosaurs and [[pterosaur]]s. The [[Osteological|osteology]] of spinosaurid teeth and bones has suggested a [[semiaquatic]] lifestyle for some members of this [[clade]]. This is further indicated by various anatomical adaptations, such as retracted eyes and nostrils; and the deepening of the tail in some taxa, which has been suggested to have aided in underwater propulsion akin to that of modern [[crocodilia]]ns. Spinosaurs are proposed to be closely related to the [[megalosaurid]] theropods of the Jurassic. This is due to both groups sharing many features such an enlarged claw on their first manual ungual and an elongated skull.<ref>{{cite journal |last1=Benson |first1=Rodger |title=A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods |journal=Zoological Journal of the Linnean Society |date=2010 |volume=158 |issue=4 |pages=882–935 |doi=10.1111/j.1096-3642.2009.00569.x |s2cid=84266680 |doi-access=free }}</ref> However, some propose that this group (which is known as the Megalosauroidea) is paraphyletic and that spinosaurs represent either the most basal [[tetanurans]]<ref>{{cite journal |title=A NEW PHYLOGENY OF THE CARNIVOROUS DINOSAURS |journal=GAIA |pages=5–61 |url=https://www.geol.umd.edu/~tholtz/gaiaphyl.pdf}}</ref> or as basal [[carnosaurs]] which are less derived than the megalosaurids.<ref>{{cite journal |last1=Rauhut |first1=Oliver |title=Probable basal allosauroid from the early Middle Jurassic Cañadón Asfalto Formation of Argentina highlights phylogenetic uncertainty in tetanuran theropod dinosaurs |journal=Scientific Reports |date=2019 |volume=9 |issue=18826 |page=18826 |doi=10.1038/s41598-019-53672-7 |pmid=31827108 |pmc=6906444 |bibcode=2019NatSR...918826R }}</ref> Some have proposed a combination of the two ideas with spinosaurs being in a monophyletic Megalosauroidea inside a more inclusive Carnosauria that is made up of both allosauroids and megalosauroids.<ref>{{cite journal |last1=Rauhut |first1=Oliver |title=Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany |journal=PNAS |date=2012 |volume=109 |issue=29 |pages=11746–11751 |doi=10.1073/pnas.1203238109 |pmid=22753486 |pmc=3406838 |bibcode=2012PNAS..10911746R |doi-access=free }}</ref>
== History of discovery ==
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On 2021 a recent discovery in [[Isle of Wight]] an island off the south coast of England, remains of a spinosaurid which is said to be of a new species is found. As per the findings, it is about 10 meters in length and weighed several tons. The prehistoric bones of the spinosaurid were found in a geological layer of rock known as the [[Vectis Formation]] in Compton Chine, it is the first identifiable theropod from the Vectis Formation. The study was led by Christopher Barker, a PhD doctoral student in vertebrate paleontology at the [[University of Southampton]].<ref>{{Cite web |author=Sana Noor Haq |title=Scientists unearth remains of one of Europe's biggest predatory dinosaurs |url=https://www.cnn.com/2022/06/09/europe/spinosaurid-dinosaur-europe-intl-scn-scli/index.html |access-date=2022-06-11 |website=CNN|date=9 June 2022 }}</ref>
In February 2024, a new spinosaurid was announced with the name of [[Riojavenatrix|''Riojavenatrix lacustris'']]. Originally discovered in [[La Rioja]] in 2005, it is the fifth spinosaurid species to be discovered in the Iberian Peninsula. It was found to have lived 120 million years ago and was around 7-8 metres long with a 1.5 metric ton body mass.<ref>{{cite web|title=Researchers discover a new species of carnivorous dinosaur in La Rioja, Spain|url=https://phys.org/news/2024-03-species-carnivorous-dinosaur-la-rioja.html|date=13 March 2024|access-date=25 May 2024|website=[[Phys.org]]}}</ref>
==Description==
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The [[Glossary of dinosaur anatomy#coracoid|coracoid]] bones of the shoulders in spinosaurids were robust and hook shaped.<ref name="Sereno Beck Dutheil et al 1998"/> The arms were relatively large and well-built; the [[Glossary of dinosaur anatomy#radius|radius]] (long bone of the forearm) was stout and usually only half as long as the [[Glossary of dinosaur anatomy#humerus|humerus]] (upper arm bone). Spinosaurid hands had three fingers, typical of [[Tetanurae|tetanurans]], and wielded an enlarged [[Glossary of dinosaur anatomy#ungual|ungual]] on the first finger (or "thumb"), which formed the bony core of a [[keratin]] claw. In genera like ''Baryonyx'' and ''Suchomimus'', the [[Glossary of dinosaur anatomy#phalanges|phalanges]] (finger bones) were of conventional length for large theropods, and bore hook-shaped, strongly curved hand claws.<ref name=Hone2017/><ref name="S.-2016" /> Based on fragmentary material from the forelimbs of ''Spinosaurus'', it appears to have had longer, more gracile hands and straighter claws than other spinosaurids.<ref name="Spinosaurus 2014">{{Cite journal |last1=Ibrahim |first1=N. |author-link=Nizar Ibrahim |last2=Sereno |first2=P. C. |last3=Dal Sasso |first3=C. |last4=Maganuco |first4=S. |last5=Fabbri |first5=M. |last6=Martill |first6=D. M. |last7=Zouhri |first7=S. |last8=Myhrvold |first8=N. |last9=Iurino |first9=D. A. |year=2014 |title=Semiaquatic adaptations in a giant predatory dinosaur |url=https://researchportal.port.ac.uk/portal/en/publications/semiaquatic-adaptations-in-a-giant-predatory-dinosaur(8f11a1ce-3265-4b3b-8c81-6f576856a87f).html |journal=Science |volume=345 |issue=6204 |pages=1613–1616 |bibcode=2014Sci...345.1613I |doi=10.1126/science.1258750 |pmid=25213375 |s2cid=34421257|doi-access=free }}</ref>
The hindlimbs of ''Suchomimus'' and ''Baryonyx'' were somewhat short and mostly conventional of other [[Megalosauroidea|megalosauroid]] theropods.<ref name=Hone2017/><ref name="S.-2016" /> ''Ichthyovenator''<nowiki/>'s hip region was reduced, having the shortest [[Glossary of dinosaur anatomy#pubis|pubis]] (pubic bone) and [[Glossary of dinosaur anatomy#ischium|ischium]] (lower and rearmost hip bone) in proportion to the [[Glossary of dinosaur anatomy#ilium|ilium]] (main hip bone) of any other known theropod.<ref name="AXRK122" /> ''Spinosaurus'' had an even smaller [[Glossary of dinosaur anatomy#pelvis|pelvis]] and hindlimbs in proportion to its body size; its legs composed just over 25 percent of the total body length. Substantially complete spinosaurid foot remains are only known from ''Spinosaurus''. Unlike most theropods—which walk on three toes, with the [[Glossary of dinosaur anatomy#hallux|hallux]] (first toe) being reduced and elevated off the ground—''Spinosaurus'' walked on four functional toes, with an enlarged hallux that came in contact with the ground. The unguals of its feet, in contrast with the deeper, smaller and recurved unguals of other theropods, were shallow, long, large in relation to the foot, and had flat bottoms. Based on comparisons with those of modern [[shorebirds]], it is
[[File:Spinosauridae sail comparison.png|alt=|thumb|left|Reconstructed [[neural spine sail]]s of four spinosaurids; clockwise from top left: ''Spinosaurus'', ''Irritator'', ''Ichthyovenator'', and ''Suchomimus''.]]
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|label1=Spinosauridae
|1={{clade
|1=Praia das Aguncheiras taxon (''[[Iberospinus]]'') <div style="{{MirrorH}}">[[File:Iberospinus natarioi by PaleoGeek.png|80px]]</div>
|label2=[[Baryonychinae]]
|2={{clade
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Several theories have been proposed about the [[biogeography]] of the spinosaurids. Since ''Suchomimus'' was more closely related to ''Baryonyx'' (from Europe) than to ''Spinosaurus''—although that genus also lived in Africa—the distribution of spinosaurids cannot be explained as [[vicariance]] resulting from [[continental rifting]].<ref name=Sereno1998/> Sereno and colleagues<ref name=Sereno1998/> proposed that spinosaurids were initially distributed across the [[supercontinent]] [[Pangea]], but split with the opening of the [[Tethys Sea]]. Spinosaurines would then have evolved in the south (Africa and South America: in [[Gondwana]]) and baryonychines in the north (Europe: in [[Laurasia]]), with ''Suchomimus'' the result of a single north-to-south [[dispersal event]].<ref name=Sereno1998/> Buffetaut and the Tunisian palaeontologist Mohamed Ouaja also suggested in 2002 that baryonychines could be the ancestors of spinosaurines, which appear to have replaced the former in Africa.<ref>{{Cite journal | volume = 173 | pages = 415–421 | year = 2002 | doi = 10.2113/173.5.415 | last1 = Buffetaut | journal = Bulletin de la Société Géologique de France | first1 = E. | title = A new specimen of ''Spinosaurus'' (Dinosauria, Theropoda) from the Lower Cretaceous of Tunisia, with remarks on the evolutionary history of the Spinosauridae | last2 = Ouaja | first2 = M. | s2cid = 53519187 | issue = 5| hdl = 2042/216 | url = http://doc.rero.ch/record/14728/files/PAL_E1854.pdf }}</ref> Milner suggested in 2003 that spinosaurids originated in Laurasia during the Jurassic, and dispersed via the Iberian [[land bridge]] into Gondwana, where they [[Evolutionary radiation|radiated]].<ref name="Milner 2003">{{cite journal |last=Milner |first=A. C. |year=2003 |title=Fish-eating theropods: A short review of the systematics, biology and palaeobiogeography of spinosaurs |journal=Actas de las II Jornadas Internacionales Sobre Paleontologýa de Dinosaurios y Su Entorno |pages=129–138}}</ref> In 2007, Buffetaut pointed out that [[palaeogeographical]] studies had demonstrated that Iberia was near northern Africa during the Early Cretaceous, which he found to confirm Milner's idea that the Iberian region was a [[Island hopping|stepping stone]] between Europe and Africa, which is supported by the presence of baryonychines in Iberia. The direction of the dispersal between Europe and Africa is still unknown,<ref name="buffetaut2007">{{cite journal |last1=Buffetaut |first1=E. |year=2007 |title=The spinosaurid dinosaur ''Baryonyx'' (Saurischia, Theropoda) in the Early Cretaceous of Portugal |journal=Geological Magazine |volume=144 |issue=6 |pages=1021–1025 |bibcode=2007GeoM..144.1021B |doi=10.1017/S0016756807003883 |s2cid=130212901|url=http://doc.rero.ch/record/13845/files/PAL_E769.pdf }}</ref> and subsequent discoveries of spinosaurid remains in Asia and possibly Australia indicate that it may have been complex.<ref name="Mateus 2011"/>
In 2016, the Spanish palaeontologist Alejandro Serrano-Martínez and colleagues reported the oldest known spinosaurid fossil, a tooth from the Middle Jurassic of Niger, which they found to suggest that spinosaurids originated in Gondwana, since other known Jurassic spinosaurid teeth are also from Africa, but they found the subsequent dispersal routes unclear.<ref name="JurassicTeeth"/> Some later studies instead suggested this tooth belonged to a [[Megalosauridae|megalosaurid]].<ref>{{Cite journal|last1=Hendrickx|first1=Christophe|last2=Mateus|first2=O.|last3=Araújo|first3=R.|last4=Choiniere|first4=J.|date=2019|title=The distribution of dental features in non-avian theropod dinosaurs: Taxonomic potential, degree of homoplasy, and major evolutionary trends|url=https://palaeo-electronica.org/content/2019/2806-dental-features-in-theropods|journal=Palaeontologia Electronica|volume=22|issue=3|pages=1–110|doi=10.26879/820| s2cid=213164229 |issn=1094-8074|hdl=11336/146011|hdl-access=free}}</ref><ref>{{Cite journal|last1=Soto|first1=M.|last2=Toriño|first2=P.|last3=Perea|first3=D.|date=2020|title=''Ceratosaurus'' (Theropoda, Ceratosauria) teeth from the Tacuarembó Formation (Late Jurassic, Uruguay)|url=http://adsabs.harvard.edu/abs/2020JSAES.10302781S|journal=Journal of South American Earth Sciences|volume=103|pages=102781|doi=10.1016/j.jsames.2020.102781|bibcode=2020JSAES.10302781S|s2cid=224842133|issn=0895-9811}}</ref> Candeiro and colleagues suggested in 2017 that spinosaurids of northern Gondwana were replaced by other predators, such as [[abelisauroids]], since no definite spinosaurid fossils are known from after the Cenomanian anywhere in the world. They attributed the disappearance of spinosaurids and other shifts in the fauna of Gondwana to changes in the environment, perhaps caused by [[Marine transgression|transgressions in sea level]].<ref name="Biogeography">{{cite journal|last1=Candeiro|first1=C. R. A.|last2=Brusatte|first2=S. L.|last3=Souza|first3=A. L.|title=Spinosaurid Dinosaurs from the Early Cretaceous of North Africa and Europe: Fossil Record, Biogeography and Extinction|journal=Anuário do Instituto de Geociências|date=2017|volume=40|issue=3|pages=294–302|doi=10.11137/2017_3_294_302|doi-access=free|hdl=20.500.11820/1bc143b5-5bd5-416b-bf10-dd28304d2c9b|hdl-access=free}}</ref> Malafaia and colleagues stated in 2020 that ''Baryonyx'' remains the oldest unquestionable spinosaurid, while acknowledging that older remains had also been tentatively assigned to the group.<ref name="Malafaia2020">{{cite journal |last1=Malafaia |first1=E. |last2=Gasulla |first2=J. M. |last3=Escaso |first3=F. |last4=Narvaéz |first4=I. |last5=Ortega |first5=F. |title=An update of the spinosaurid (Dinosauria: Theropoda) fossil record from the Lower Cretaceous of the Iberian Peninsula: distribution, diversity, and evolutionary history |journal=Journal of Iberian Geology |date=2020 |volume=46 |issue=4 |pages=431–444 |doi=10.1007/s41513-020-00138-9|bibcode=2020JIbG...46..431M |s2cid=222149842 }}</ref> Barker and colleagues found support for a European origin for spinosaurids in 2021, with an expansion to Asia and Gondwana during the first half of the Early Cretaceous. In contrast to Sereno, these authors suggested there had been at least two dispersal events from Europe to Africa, leading to ''Suchomimus'' and the African part of Spinosaurinae.<ref name="NewSpinosaurids">{{cite journal |last1=Barker |first1=C. T. |last2=Hone |first2=D. W. E. |last3=Naish |first3=D. |last4=Cau |first4=A. |last5=Lockwood |first5=J. A. F. |last6=Foster |first6=B. |last7=Clarkin |first7=C. E. |last8=Schneider |first8=P. |last9=Gostling |first9=N. J. |title=New spinosaurids from the Wessex Formation (Early Cretaceous, UK) and the European origins of Spinosauridae |journal=Scientific Reports |date=2021 |volume=11 |issue=1 |pages=19340 | pmid=34588472| doi=10.1038/s41598-021-97870-8|pmc=8481559|bibcode=2021NatSR..1119340B }}</ref>
==Paleobiology==
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Direct fossil evidence shows that spinosaurids fed on fish as well as a variety of other small to medium-sized animals, including dinosaurs. ''Baryonyx'' was found with scales of the prehistoric fish ''[[Scheenstia]]'' in its body cavity, and these were abraded, hypothetically by gastric juices. Bones of a young ''[[Iguanodon]]'', also abraded, were found alongside this specimen. If these represent ''Baryonyx''’s meal, the animal was, whether in this case a hunter, or a scavenger, an eater of more diverse fare than fish.<ref name="Rayfield20112" /><ref name="suesetal20022" /><ref name="charigmilner19973" /> Moreover, there is a documented example of a spinosaurid having eaten a [[pterosaur]], as one ''Irritator'' tooth was found lodged within the fossil vertebrae of an [[Ornithocheiridae|ornithocheirid]] pterosaur found in the [[Romualdo Formation]] of Brazil. This may represent a predation or a scavenging event.<ref>{{cite journal |last1=Witton |first1=Mark P. |title=Pterosaurs in Mesozoic food webs: a review of fossil evidence |journal=Geological Society, London, Special Publications |date=2018 |volume=455 |issue=1 |pages=7–23 |doi=10.1144/SP455.3 |bibcode=2018GSLSP.455....7W |s2cid=90573936 }}</ref><ref name="Buffetautetal.20042">{{cite journal |last1=Buffetaut |first1=Eric |last2=Martill |first2=David |last3=Escuillié |first3=François |title=Pterosaurs as part of a spinosaur diet |journal=Nature |date=July 2004 |volume=430 |issue=6995 |pages=33 |doi=10.1038/430033a |pmid=15229562 |bibcode=2004Natur.429...33B |s2cid=4398855 |doi-access=free }}</ref> A fossil snout referred to ''Spinosaurus'' was discovered with a vertebra from the [[Sclerorhynchidae|sclerorhynchid]] ''[[Onchopristis]]'' embedded in it.<ref name="Sasso Maganuco Buffetaut Mendez 2005"/> In the [[Sao Khua Formation]] of Thailand, isolated tooth crowns from ''Siamosaurus'' have been found in association with [[Sauropoda|sauropod]] remains, indicating possible predation or scavenging.<ref>{{cite journal |last1=Buffetaut |first1=Eric |last2=Suteethorn |first2=Varavudh |title=The dinosaur fauna of the Sao Khua Formation of Thailand and the beginning of the Cretaceous radiation of dinosaurs in Asia |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=June 1999 |volume=150 |issue=1–2 |pages=13–23 |doi=10.1016/S0031-0182(99)00004-8 |bibcode=1999PPP...150...13B |url=http://doc.rero.ch/record/14471/files/PAL_E1664.pdf }}</ref> The Portuguese Iberospinus fossils were also found associated with isolated Iguanodon teeth, and those cases are listed; along with other such associations as support for opportunistic feeding behaviour in spinosaurids.<ref>{{cite journal | pmc=4703214 | date=2016 | last1=Hendrickx | first1=C. | last2=Mateus | first2=O. | last3=Buffetaut | first3=E. | title=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 | journal=PLOS ONE | volume=11 | issue=1 | pages=e0144695 | doi=10.1371/journal.pone.0144695 | pmid=26734729 | bibcode=2016PLoSO..1144695H | doi-access=free }}</ref>
A 2018 study by Auguste Hassler and colleagues of [[calcium isotopes]] in the teeth of North African theropods found that spinosaurids had a mixed diet of fish and herbivorous dinosaurs, whereas the other theropods examined ([[abelisaurids]] and [[carcharodontosaurids]]) mainly fed on herbivorous dinosaurs. This might indicate [[ecological partitioning]] between these theropods.<ref name="Calciumisotopes">{{cite journal |last1=Hassler |first1=A. |last2=Martin |first2=J. E. |last3=Amiot |first3=R. |last4=Tacail |first4=T. |last5=Godet |first5=F. Arnaud |last6=Allain |first6=R. |last7=Balter |first7=V. |title=Calcium isotopes offer clues on resource partitioning among Cretaceous predatory dinosaurs |journal=Proceedings of the Royal Society B: Biological Sciences |date=11 April 2018 |volume=285 |issue=1876 |pages=20180197 |doi=10.1098/rspb.2018.0197 |pmid=29643213 |pmc=5904318 }}</ref> Later in 2018, [[Tito Aureliano]] and colleagues presented a possible scenario for the [[food web]] of Brazilian Romualdo Formation. The researchers proposed that the diet of spinosaurines from this environment may have included—in addition to pterosaurs—terrestrial and aquatic [[crocodyliforms]], juveniles of their own species, turtles, and small to medium-sized dinosaurs. This would have made spinosaurines [[apex predator]]s within this particular ecosystem.<ref name="Aureliano Ghilardi Buck et al 2018"/>
A 2024 study by D'Amore et al., further vindicates the theory that spinosaurids were similar in niche to generalist or macro-generalist crocodilians. This study likewise suggests their jaws and teeth were well-suited to quick strikes and deep, puncturing bites, but not for slicing flesh or crushing bones. In particular, baryonychine spinosaurids probably did little oral processing of their prey when feeding, but by comparison, spinosaurines were found to be quite capable of processing the meat of relatively large vertebrate prey. None of these findings suggest any spinosaurids from either subfamily were restricted only to fish and small aquatic vertebrates.<ref>{{Cite journal |last1=D'Amore |first1=Domenic C. |last2=Johnson-Ransom |first2=Evan |last3=Snively |first3=Eric |last4=Hone |first4=David W. E. |date=2024-08-28 |title=Prey size and ecological separation in spinosaurid theropods based on heterodonty and rostrum shape |url=https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25563 |journal=The Anatomical Record |language=en |doi=10.1002/ar.25563 |issn=1932-8486}}</ref>
=== Forelimb function ===
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=== Habitat preference ===
A 2010 publication by Romain Amiot and colleagues found that [[isotopes of oxygen|oxygen isotope]] ratios of spinosaurid bones indicates semiaquatic lifestyles. Isotope ratios from teeth from ''Baryonyx'', ''Irritator'', ''Siamosaurus'', and ''Spinosaurus'' were compared with isotopic compositions from contemporaneous theropods, turtles, and crocodilians. The study found that, among theropods, spinosaurid isotope ratios were closer to those of turtles and crocodilians. ''Siamosaurus'' specimens tended to have the largest difference from the ratios of other theropods, and ''Spinosaurus'' tended to have the least difference. The authors concluded that spinosaurids, like modern crocodilians and hippopotamuses, spent much of their daily lives in water. The authors also suggested that semiaquatic habits and piscivory in spinosaurids can explain how spinosaurids coexisted with other large theropods: by feeding on different prey items and living in different habitats, the different types of theropods would have been out of direct competition.<ref name="RMetal10">{{cite journal|last1=Amiot|first1=R.|last2=Buffetaut|first2=E.|last3=Lécuyer|first3=C.|last4=Wang|first4=X.|last5=Boudad|first5=L.|last6=Ding|first6=Z.|last7=Fourel|first7=F.|last8=Hutt|first8=S.|last9=Martineau|first9=F.|last10=Medeiros|first10=A.|last11=Mo|first11=J.|year=2010|title=Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods|journal=Geology|volume=38|issue=2|pages=139–142|bibcode=2010Geo....38..139A|doi=10.1130/G30402.1|last12=Simon|first12=L.|last13=Suteethorn|first13=V.|last14=Sweetman|first14=S.|last15=Tong|first15=H.|last16=Zhang|first16=F.|last17=Zhou|first17=Z.}}</ref>
In 2018, an analysis was conducted on the partial [[Glossary of dinosaur anatomy#tibia|tibia]] of an indeterminate spinosaurine from the early [[Albian]], the bone was from a sub-adult between 7 and 13 m (22 and 42 ft) in length still growing moderately fast before its death. This specimen (LPP-PV-0042) was found in the [[Araripe Basin]] of Brazil and taken to the [[University of San Carlos]] for a [[CT scan|CT Scan]], where it revealed [[osteosclerosis]] (high bone density).<ref name="Aureliano Ghilardi Buck et al 2018"/> This condition had previously only been observed in ''Spinosaurus,'' as a possible way of controlling its buoyancy.<ref name="Spinosaurus 2014" /> The presence of this condition on the leg fragment showed that semi-aquatic adaptations in spinosaurids were already present at least 10 million years before ''Spinosaurus aegyptiacus'' appeared. According to the [[phylogenetic bracketing]] method, this high bone density might have been present in all spinosaurines.<ref name="Aureliano Ghilardi Buck et al 2018"/> In 2020, a scientific paper by paleontologists published in the scientific journal [[Cretaceous Research]] found taphonomic evidence in the Kem Kem group that would support ''Spinosaurus'' being a semi-aquatic dinosaur.<ref>{{cite journal |last1=Beevor |first1=Thomas |last2=Quigley |first2=Aaron |last3=Smith |first3=Roy E. |last4=Smyth |first4=Robert S.H. |last5=Ibrahim |first5=Nizar |last6=Zouhri |first6=Samir |last7=Martill |first7=David M. |title=Taphonomic evidence supports an aquatic lifestyle for Spinosaurus |journal=Cretaceous Research |date=January 2021 |volume=117 |pages=104627 |doi=10.1016/j.cretres.2020.104627 |bibcode=2021CrRes.11704627B |s2cid=224888268 |url=https://researchportal.port.ac.uk/portal/en/publications/taphonomic-evidence-supports-an-aquatic-lifestyle-for-spinosaurus(e7fb2358-2ac6-4b6c-9697-225a525e8366).html }}</ref> However, research conducted in 2023 cited the immediate assumption of Spinosaurids being avid divers due to correlations in bone compactness as being subject to errors, such as flawed statistical methods and measurements, as well as sampling bias.<ref>{{cite
A 2018 study of [[buoyancy]] (through simulation with 3D models) by the Canadian palaeontologist Donald M. Henderson found that distantly related theropods floated as well as the tested spinosaurs, and instead supported they would have stayed by the shorelines or shallow water rather than being semi-aquatic.<ref name="Henderson">{{cite journal|last1=Henderson|first1=D. M.|date=2018|title=A buoyancy, balance and stability challenge to the hypothesis of a semi-aquatic ''Spinosaurus'' Stromer, 1915 (Dinosauria: Theropoda)|journal=PeerJ|volume=6|pages=e5409|doi=10.7717/peerj.5409|pmc=6098948|pmid=30128195 |doi-access=free }}</ref>
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