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Dinopedia
Spinosauridae
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Spinosauridae
Stromer et al., 1915
Type species
Spinosaurus aegyptiacus
Stromer, 1915
Synonyms
  • Baryonychidae Charig & Milner, 1986
  • Irritatoridae Martill et al., 1996

Spinosauridae (Greek for "Spined Lizard") is a family of megalosauroids, where the size varies between medium to very large, theropod dinosaurs. The species Spinosaurus; from which the name of the family & subfamily borrow their names; is the largest terrestrial predator known, and likely reached lengths of 15 to 16 meters (49-50 ft) or, potentially; more.

Most spinosaurids lived during the medium to late Cretaceous Period, and fossils of them have been recovered worldwide, showing that the spinosauridae were an adaptable and rather successful family of Theropods.

The range of these theropods spread throughout all over the Africa, Europe, South America, Asia, and Australia. All known Spinosaurid species were rather large bipedal carnivores with crocodile-like skulls lined with teeth. Some species have had small crests on top of their heads. All known spinosaurids shoulders were robust, bearing large forelimbs with enlarged claws; something that is extremely rare throughout all known theropod species. Some Species from this genera exhibited unusually elongated neural spines, which might have supported sails/humps of skin or fat tissue. All known spinosaurid species diets were composed of both Terrestrial and Aquatic prey items; indicating that the spinosauridae were rather generalistic carnivores.

Detailed Description

The smallest spinosaurid species known was the Irritator, which it was between 6 to 8 meters in length and 1 tonne (1.1 short tons) in weight. While Ichthyovenator, Baryonyx, and Suchomimus ranged from 7.5 to 12 meters long, and weighing between 1 and 5.2 tonnes (1.2 and 5.7 short tons). Spinosaurus was the largest known spinosaurid species, capable of reaching lengths over than 15 meters (49 ft) and weighing between 8 and 20.9 tonnes (7.7 and 23.0 short tons), making the species the largest known terrestrial predator so far ! The Spinosauridae have had a phenomena that it extremely rare among all known theropod species & clade; the spinosaurids had large arms with enlarged claws on their hands. They had sharp hook-shaped claws. Spinosaurus; the species from the family is known for; have had elongated neural spines, some even over a meter tall, which have been reconstructed as a sail or hump running down its back. In the case of Ichthyovenator, this sail is a half a meter at its highest, split into two at the vertebrae. The Suchomimus was also had a low, ridge-like sail over its hips, noticeably smaller the Spinosaurus. Baryonyx, however, lacked a sail. Meanwhile these structures function/s are unknown, they might have had many proposed/theoretical functions, such as thermoregulation, to aid animal gather heat and/or cooling down, to store energy or insulate the animal, or for display purposes, such as intimidating rivals, predators, or attracting mates.

Forelimb functionality

The use of the robust forelimbs and giant recurved claws of spinosaur remains a debated topic. Charig and Milner speculated in 1986 that Baryonyx may have crouched by the riverbank and used its claws to gaff fish out of the water, similarly to grizzly bears.[1]

a model of Spinosaurus Skeletal by Miyess

In 1987, British biologist Andrew Kitchener argued that with both its crocodile-like snout and enlarged claws, Baryonyx seemed to have too many adaptations for piscivory when one would have been enough. Kitchener instead postulated that Baryonyx more likely used its arms to scavenge the corpses of large dinosaurs, such as Iguanodon, by breaking into the carcass with the large claws, and subsequently probing for viscera with its long snout.[2]

In their 1997 article, Charig and Milner rejected this hypothesis, pointing out that in most cases, a carcass would have already been largely emptied out by its initial predators. Later research has also ruled out this sort of specialized scavenging.[3][4]

In 1986, Charig and Milner suggested that the robust forelimbs and giant thumb claws would have been Baryonyx's primary method of capturing, killing, and tearing apart large prey; whereas its long snout would have been used mostly for fishing. A 2005 study by Canadian paleontologist the François Therrien and colleagues agreed that spinosaur forelimbs were probably used for hunting larger prey items, given that their snouts could not resist the bending stress.[5][6]

a skeletal model of Spinosaurus by getawaytrike


In a 2017 review of the family, David Hone and Holtz considered possible functions in digging for water sources or hard to reach prey, as well as burrowing into soil to construct nests.[7]

Timespan

Spinosaurids have lived through all of the late jurassic to the late cretaceous period.[8] Spinosaurids are known to exist from as early as the Late Jurassic; as evidence of the Ostafrikasaurus (although the specific theropod classification issues are complicated) from east africa.; albeit there are fossil evidence, as well as teeth interpretations attributed the Spinosauridae that indicate the megalisauroid family could be even more ancient.[9]

Habitat

a Spinosaurus Render by sergey krasovskiy, model based off Models prior to 2020.

A 2010 publication indicates that they've been found that oxygen isotope ratios of some spinosaurid bones; that thought to be indicate semi-aquatic lifestyle for some spinosaurid species. The concluded Isotope ratios from teeth of 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 slightly closer; albeit clearly not the same; to those of turtles and crocodilians. The Siamosaurus specimens tended to have the largest difference from the ratios of other theropods, and Spinosaurus species have the least difference; indicating that the different species of spinosaurids clearly have had different preferences; meanwhile some being more Terrestrial like Spinosaurus some being more amphibious; able to live and travel between both land and water as in the case of Siamosaurus. The authors concluded that species of spinosaurids, like modern crocodilians, spent much of their daily lives in water.However; lately, there has been counter-evidence and anti-thesis of this concluded theory, as the latest evidence shows that some spinosaurid species likely doesn't even had the capability of swimming; nor spending time at noticeably deep water; at all. This latest evidence likely points out that most known spinosaurid species were more Terrestrial (land dwelling) than previously thought and they ; theoretically; venture only to shallow water. [10][11]


A 2018 study of buoyancy (through simulation with 3D models) by the Canadian paleontologist 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 [12]

An Asian Spinosaurid, most likely Siamosaurus, feasting on a sauropod. On an asian paleontology site, spinosaurid teeth found be with direct assosication with sauropods.

Diet

Direct fossil evidence clearly shows that spinosaurids were generalistic carnivores; not piscivores as previously thought. A Baryonyx specimen was found with scales of the prehistoric fish, most likely Scheenstia, and Bones of a young Iguanodon in its body cavity. These represent that the Baryonyx was, whether in this case a hunter, or a scavenger, was an eater far more diverse and generalistic rather than piscivore. Moreover, there is a well documented example of an another spinosaurid; Irritator; has been an another diverse carnivore; as a spinosaurid teeth found to be embedded within the fossil vertebrae of a large pterosaur, found in the Santana Formation of Brazil. Lately, there has been even more evidence that concluded the spinosauridae as carnivores; as the Siamosaurus remains been found with direct association with sauropod remains [13]

The Case of İrritator clearly adds moreevidence to the Carnivore and generalistic behaviore of spinosaurid species.

The description of the Fukui Spinosauridae, a rather underacknowledged and undepicted species of Spinosaurid, hunting and subduing a crocodylimorph. Artwork done by artist Palaeotaku

A private fossil, the vertebrae of Carcharodontosaurus have inlaid spinosaurus teeth.

Furthermore, additional evidence for a generalistic and more carnivorous diet; and the apex position for Spinosaurinae; in this case through İritator; comes by a study from 2018, where Aureliano and colleagues presented a possible scenario for the food web of the Romualdo Formation. The researchers proposed that spinosaurines from the formation may have also preyed on terrestrial and aquatic crocodyliforms, same-species juveniles, turtles, and small to medium-sized dinosaurs. This would have made spinosaurines apex predators within the ecosystem.[14]

A 2016 study by the Belgian palaeontologist Christophe Hendrickx and colleagues found that adult spinosaurs could displace their mandibular rami (halves of the lower jaw) sideways when the jaw was depressed, which allowed the pharynx (opening that connects the mouth to the oesophagus) to be widened. This jaw-articulation is similar to that seen in pterosaurs and living pelicans, and would likewise have allowed spinosaurids to swallow large prey such as fish and other animals. They also reported that the possible Portuguese Baryonyx fossils were found associated with isolated Iguanodon teeth, and listed it along with other such associations as support for opportunistic feeding behaviour in spinosaurs.[15]

Another direct evidence, has been discovered at 2016, Spanish palaeontologist Alejandro Serrano-Martínez and colleagues described a possible spinosaurid tooth, catalogued as MUPE HB-87, from the Irhazer Shale of Niger. Found in association with a skeleton of the sauropod dinosaur Spinophorosaurus, the tooth likely dates to the Bathonian stage of the Middle Jurassic, 14 million years prior to Ostafrikasaurus. If this identification is correct, MUPE HB-87 represents the oldest known evidence of spinosaurids in the fossil record. Based on this specimen, the authors proposed a new evolutionary model for the transition between "normal" theropod teeth, to those of spinosaurids. [9]

More recent studies widely interpreted the Spinosaurus Aegyptiacus being more generalist in its dietary behavior, akin to modern wading avians such as Pelicans, Storks, Skua and Giant Petrel, instead of being akin to hyper specialized, as Gharials and Dolphins.[16][17] A rather underacknowledged event comes from a private fossil, the vertebrae of Carcharodontosaurus have spinosaurus bites and inlaid spinosaurus teeth. If this fossil is validated, it proved that the spinosaurus did eat or attacked other dinosaurs.

Bite Force

A private fossil, the vertebrae of Carcharodontosaurus have spinosaurus bites.

Spinosaurus and Baryonyx Skull comparisons, Spinosaurus having the more robust skull

A 2013 beam-theory study by the British palaeontologists Andrew R. Cuff and Rayfield compared the biomechanics of CT-scanned spinosaurid snouts with those of extant crocodilians, and found the snouts of Baryonyx and Spinosaurus similar in their resistance to bending and torsion. Baryonyx was found to have relatively high resistance in the snout to dorsoventral bending compared with Spinosaurus and the gharial. The authors concluded (in contrast to the 2007 study) that Baryonyx performed differently than the gharial; spinosaurids were not exclusive piscivores, and their diet was determined by their individual size.[18]

A preceding 2005 beam-theory study by the Canadian paleontologist François Therrien and colleagues was unable to reconstruct force profiles of Baryonyx, but found that the related Suchomimus would have used the front part of its jaws to capture prey, and suggested that the jaws of spinosaurids were adapted for hunting smaller terrestrial prey in addition to fish. They envisaged that spinosaurids could have captured smal to medium sized prey with the rosette of teeth at the front of the jaws, and finished it by shaking it. Larger prey would instead have been captured and killed with their forelimbs instead of their bite, since their skulls would not be able to resist the bending stress. They also agreed that the conical teeth of spinosaurids were well-developed for impaling and holding prey, with their shape enabling them to withstand bending loads from all directions.[19]

Confirmed Members

Well known, Official Members of the Spinosauridae family: Spinosaurus, Oxalaia, Suchomimus, Baryonyx, Ichthyovenator, and Irritator. Artwork by: USIK

References

  1. https://ui.adsabs.harvard.edu/abs/1986Natur.324..359C
  2. http://biostor.org/reference/110558
  3. http://biostor.org/reference/110558
  4. https://qmro.qmul.ac.uk/xmlui/handle/123456789/49404
  5. http://biostor.org/reference/110558
  6. https://www.researchgate.net/publication/259010793_Bite_me_Biomechanical_models_of_theropod_mandibles_and_implications_for_feeding_behavior
  7. https://qmro.qmul.ac.uk/xmlui/handle/123456789/49404
  8. https://www.sciencedirect.com/science/article/abs/pii/S0195667118301162
  9. 9.0 9.1 https://www.research.manchester.ac.uk/portal/en/publications/isolated-theropod-teeth-from-the-middle-jurassic-of-niger-and-the-early-dental-evolution-of-spinosauridae(17dc3f80-67cb-455d-9f58-b3defbe7d2aa).html
  10. https://royaltyrrellmuseum.wordpress.com/2018/08/16/new-research-refutes-claims-that-spinosaurus-was-semi-aquatic/
  11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6098948/
  12. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6098948/
  13. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0147031
  14. https://www.sciencedirect.com/science/article/pii/S0195667117305153?via%3Dihub
  15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4703214/
  16. https://twitter.com/ivankay17/status/1354002825219624960
  17. https://archosaurmusings.wordpress.com/2021/01/26/the-evidence-for-spinosaurus-being-a-specialist-aquatic-predator-and-good-swimmer-is-weak/amp/?__twitter_impression=true
  18. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3665537/
  19. https://www.researchgate.net/publication/259010793_Bite_me_Biomechanical_models_of_theropod_mandibles_and_implications_for_feeding_behavior
  20. http://rsbl.royalsocietypublishing.org/content/7/6/933
  21. https://www.researchgate.net/publication/51238670_First_spinosaurid_dinosaur_from_Australia_and_the_cosmopolitanism_of_Cretaceous_dinosaur_faunas
  22. https://www.researchgate.net/publication/350343224_Spinosaurid_teeth_from_the_Lower_Cretaceous_Kitadani_Formation_of_the_Tetori_Group_Fukui_Japan
  23. https://www.sciencedaily.com/releases/2014/02/140224204737.htm
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