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Spinosauridae
Temporal range: Late Jurassic – Late Cretaceous
Possible Late Maastrichtian record
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Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Order: Saurischia
Suborder: Theropoda
Family: Spinosauridae
Stromer et al., 1915
Type species
Spinosaurus aegyptiacus
Stromer, 1915
Synonyms
RRRspinosaurus

Spinosauridae (meaning "spined lizards") is a family of megalosauroid, 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 16 m (49 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 throught 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 spinosaurid's shoulders were robust, bearing large forelimbs with enlarged claws; something that is extremely rare throught 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; indocating 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've 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, noticably smaller the Spinosaurus. Baryonyx, however, lacked a sail. Meanwhile these structures function/s are unknown, they might have had many proposed/theorotical 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.

Amazing-Walking-With-Dinosaurs-Images-HD-Wallpapers

spinosaurus aegyptiacus the prime spinosaurid species that represents the Spinosauridae

Timespan

Spinosaurids've lived through all of the late jurassic to the late cretaceous period. Spinosaurids are known to exist from as early as the Late Jurassic; as evidence of the Ostafrikasaurus from east africa.

Habitat

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 Siasmosaurus. 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 noticably 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 ; theorotically; venture only to shallow water. [1][2]

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 [3]

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
Irritator

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

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 siasmosaurus remains've been found with direct assossication with sauropod remains [4]

Journal.pone.0147031.g005

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

 

  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. [5]

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.[6]

Bite Force

 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.[7]

A preceding 2005 beam-theory study by the Canadian palaeontologist 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.[8]

Spinosauridae by vitor silva-d5g3w1b

Several members of the Spinosauridae family: from left to right, Spinosaurus, Oxalaia, Suchomimus, Baroynyx, Ichthyovenator, and Irritator


Confirmed Members

References

  1. https://royaltyrrellmuseum.wordpress.com/2018/08/16/new-research-refutes-claims-that-spinosaurus-was-semi-aquatic/
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6098948/
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6098948/
  4. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0147031
  5. https://www.sciencedirect.com/science/article/pii/S0195667117305153?via%3Dihub
  6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4703214/
  7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3665537/
  8. https://www.researchgate.net/publication/259010793_Bite_me_Biomechanical_models_of_theropod_mandibles_and_implications_for_feeding_behavior
  9. http://rsbl.royalsocietypublishing.org/content/7/6/933
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