Spinosauridae (Greek for "spined lizard") is a family of megalosauroids in which the size varies between medium to very large theropod dinosaurs. The genus Spinosaurus, from where the name of the family and the subfamilies borrow their names, is also the longest and tallest terrestrial predator known so far in science. It likely reached lengths of 14.5 - 16 meters.
Most spinosaurids lived during the medium to late Cretaceous Period, and fossils of them have been recovered worldwide, showing that the spinosaurids were an adaptable, rather successful and well spread family of theropods.
Although a large portion of these records need more verification, the majority of them show that spinosaurids lived earlier during the Jurassic Period as well as later times during the Late Cretaceous.[1][2] The range of these theropods spread throughout all over the Africa, Europe, South America, Asia, and Australia. The spinosaurids are also the primary dominant theropods of the Lower Cretaceous region and peninsula of Iberia.[3]
All known spinosaurid genera were rather large bipedal[4] carnivores with noticeably crocodile-like skulls lined with sharp teeth. Some species have been proven to have had small crests on top of their heads. The exact purpose of these crests is unclear; albeit basing off of modern avians (roosters, peafowls, and swans) and lizards (such as sailfin lizards and basilisks) that also have such structures, a crest's main purpose is often inter-species recognition and attracting the opposite sex.
All known spinosaurid shoulders were more robust, bearing large forelimbs with huge claws, something that is quite uncommon throughout all known non-avian theropod clades and species. Some genera also exhibited unusually elongated neural spines, which supported sails.
Modern Spinosaurus diagram chart. Representing most well known specimens Credit: SpinoInWonderland
The smallest spinosaurid genus known is the Irritator, which measured between 6 and 8 metres long and weighed around 1 tonne (1.1 short tons). Though Camarillasaurus may have been smaller, its remains are too fragmentary to know for now. On the other hand, Ichthyovenator, Baryonyxand Suchomimus, larger genera of spinosaurids, ranging from 7.5 to 12 meters long, and weighing between 1.7 to 5.2 tonnes (1.5 and 5.7 short tons).
Spinosaurus was the largest known spinosaurid species, capable of reaching lengths of 14-15 meters and weighing around 7-8 tonnes, making them amongst the largest known theropods so far.[5][6]
However some paleontologists did, unofficially and informally, proclaim that the uppermost estimated limits for this particular theropod could potentially be higher than previously theorised, it is still quite a debated and questionable issue.[7][8][9] The Spinosaurus had sharphook-shaped claws and had highly elongated neural spines, some even over a meter tall, which have been reconstructed as a sail or hump running down its back. Due to its large sail and overall size, Spinosaurus has become the most well-known spinosaurid in pop culture.
The MSNM-V specimen of Spinosaurus aegypticus. Less likely Sigilmassasaurus or other close Spinosaueinae.
The well known MSNM-V Specimen in comparission to a human
In the case of Ichthyovenator, a smaller genus, its sail is a half a meter at its highest in comparison, split into two at the vertebrae.
NMC 41852 or NMC 42852 : a humerus, claimed by Cau et. al to be comparable to Limaysaurus and placed it as a a rebbachisaur. However it is later determined by Ibrahim et al. (2014) to be real Spinosaur affinity. If its assignment to Spinosaurus is legitimately confirmed, it would extend the weight limit of the theropod more than know. 10+ tons.
The Suchomimus also had a low, ridge-like sail over its hips, noticeably smaller the Spinosaurus. Baryonyx, however, entirely lacked any sail. While the exact function of these structures are unknown, there have been many theoretical functions such as to help the animal gather heat and/or cool down (thermoregulation); to store energy or insulate the animal; for display purposes, such as intimidating rivals, predators, attracting mates; or all/some of the options combined.
The Spinosaurus specimen NHMUK-R; estimated to attain either a similar size to MSNM-V or noticeably larger.
The Spinosauridae family has been separated into two distinct subgroups, Spinosaurinae and Baryonychinae. The Subgroups also include tribes and sub tribes such as Ceratosuchopsini.
According to a scientific study officially published in 2023[10][11], spinosauridae subfamilies, in particular specimens taken as exemplary samples and clade representatives from Baryonychidae, reveal that their brain anatomy and skull cavity structure have no identifiable differentiation or any significant deviation from other common theropod clades; particularly Megalosauridae .
Spinosaurus Skull Reconstruction
The results interpreted are that these theropods, presumably, showed similar behavior and traits with other theropods due to their brain structure.[12][13][14][15][16]
Commenting on the results, lead-author of the study, PhD student Chris Barker (University of Southampton), stated:
“Despite their unusual ecology, it seems the brains and senses of these early spinosaurids retained many aspects in common with other large-bodied theropods – there is no evidence that their semi-aquatic lifestyles are reflected in the way their brains are organized.“
The gigantic baryonychinae spinosaurid referred to as The '' White rock Spinosaurid '' or also being unofficially named "Vectispinus" comes in a close second place in terms of spinosaurid size, that being in the most genereous estimations and diagrams, and given the fact that the remains were extremely fragmentary. It was given a length between 10.8 meters at minimum to 13.3 meters at maximum, and so these remains could have represented a truly large spinosaurid. It was also given a nickname, being '' The Largest Theropod of Europe ''. However, these estimates could be incorrect due to the more fragmentary nature of its remains.
Forelimb functionality[]
A closer look at the robust, massive and powerful arms and claws of Suchomimus
The use of the robust forelimbs and giant recurved claws of spinosaurids 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.[17]
In 1987, British biologist Andrew Kitchener argued that with both its crocodile-like snout and enlarged claws, Baryonyx seemed to have many adaptations for a piscivorous diet, but all of these adaptations also made it so that it was well-adapted for scavenging, which was his theory.
Baryonyx skull and arm structure
Kitchener instead postulated that Baryonyx more likely used its arms to scavenge the corpses of any available large dinosaurs, such as Iguanodon, by breaking and tearing right into the carcass of the animal with its enlarged claws, and potentially even probing for viscera with its long snout.[18]
Suchomimus's massive arms and claws in comperission to Tyrannosaurus arms and Homo sapiens sapiens ( ie. Modern Human )"
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 and earlier arriving scavengers. Mote recent research also ruled out this sort of specialized scavenging.[19][20]
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 larger aquatic prey, whereas its long snout would have been used mostly for fishing and hunting other aquatic vertebrates. A 2005 study by Canadian paleontologist François Therrien and his colleagues agreed that spinosaurid forelimbs were probably used for hunting larger prey items, given that their snouts could resist the bending stress too much.[21][22]
In a 2017 review of the family, David Hone and Holtz considered several additional possible functions for the dinosaur's forelimbs in digging for water sources to catch hard to reach prey, as well as burrowing into soil to construct well developed, durable nests.[23]
A Restored hand specimen noted for belonging to a Spinosaurus is currently held in private collection; although the files being available for observation. The Claw shows enlarger fingers; specifically the third finger as well as all fingers having larger claws. Showing Spinosaurus hands are indeed functional.[24][25] A known rarity amongst The Theropoda group.
Timespan[]
Spinosaurids have lived through all of th early-middle jurassic[26] to the late cretaceous period.[27] 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 more recent fossil evidence, as teeth interpretations attributed the Spinosauridae that indicate the megalisauroid family could be even more ancient. As probable; remains with more likely association to Spinosaurids from India to Niger have been recorded.[1][26][28]
MUPE HB-87. Presumed; theorized to; be the oldest known Ancestral Spinosauridae from Niger; Early-Middle Jurassic period.
There are numbers of noticeable fossil records that might; potentially; indicate that the Spinosaurids were evolved earlier in Jurassic era ( as early as middle to early middle jurassic period ) [29][1][28] as well as existed ever more throughout later timescale of middle cretaceous[30] era to the late cretaceous[2]; albeit these reports need further verification.
A study conducted in 2017; linked Spinosaurids extinction directly to the change throughout their environment, climate as well as changes and rise of the sea levels. They theorized that The Spinosaurids from the northern parts of Gondwana were replaced by other predatory theropods, such as abelisauroids, since no definite spinosaurid fossils are known from after the Cenomanian anywhere in the world; as of now.[31]
Habitat[]
Semiaquatic oxygen isotope ratios clearly hasn't been observed on Spinosaurus specimens from Tunisia to Morocco ( including Libya; Algeria specimens ). According to study itself Spinosaurus aegyptiacus shown the Least Difference in isotope ratios and had a closer ratio to Other regular Theropod species.
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, particularly specimens from Tunusia, Libya; Algeria and Morocco, have the least difference compared to other Theropod species.[32]
Recent (2022) Skeletal Reconstructions of Suchomimus & Spinosaurus. Credit: Paul C Sereno Nathan Myhrvold and Donald M Henderson
These results are clearly indicating the situation that different species of spinosaurids clearly have had more differentiated habitat and lifestyle preferences; meanwhile some being more terrestrial like Spinosaurus aegyptiacus itself meanwhile some species being more amphibious; able to live and travel between both land and water as in the case of Siamosaurus.
The authors concluded that some species of spinosaurids, like modern crocodilians, hippopotamuses and other species like water wading birds; some species of snakes such as anacondas; spent much of their daily lives in and around water.
A sidenote to this theory is that the authors indicated a more amphibious existence for some Spinosaurid species; as they pointed this fact out as '' being able to switch between Terrestrial and Aquatic habitats '' for more diverse viability of prey items as well as lessening the competition to a degree. Although they did not stated the aforementioned species of Spinosaurids were entirely or exclusively reliant on water. They explained that Spinosaurids were able change or 'switch' between aquatic and terrestrial habitats easily and were able traverse between these habitats regularly.[32]
a model and reconstruction of Spinosaurus aegyptiacus by: Vimmemoriaeuniversum
They assigned a more amphibious existence for Spinosaurids; akin to modern animals such as some species of reptiles such as basilisk and sailfin lizard; giant species of serpents such as The Anaconda; several species of crocodilians; hippopotamus'es, herons, egrets, seagulls, some species of bears ( grizzly bears and polar bears for example ), several species of modern varanids ( nile monitors for example ), skuas, jaegers and similar animals.
They did not stated or pointed out that the aformentioned spinosaurid species were exclusively semi-aquatic or almost entirely and solely reliant on aquatic habitats such as cormorant birds; pelicans, walruses, seals, beavers, salamanders or sea snakes. [32]
However; there are 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. [33][34]
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 [35]
A 2022 study conducted by Nizar Ibrahim. The analysis found that Spinosaurus—and, surprisingly, its British cousin Baryonyx—had highly dense bone walls like penguins do, suggesting they likely spent much of their time in the water and hunted down aquatic prey. Land animal groups that made the evolutionary transition to the water, such as whales, increased bone density was one of the first traits to appear, with the bones acting as energy-saving ballast.
The aegyptiacus model. Credit: miyess
So to test whether spinosaurids were adapted to the water, the researchers compiled digitized cross sections of the ribs and femurs of more than 200 different types of amniotes, the broad group of animals that includes modern reptiles, birds, and mammals, as well as a mix of ancient, extinct creatures including dinosaurs.
The team then compared the bone densities with the animals’ known abilities to forage underwater or fly. The analysis showed that highly dense bones were tightly correlated with an animal frequently diving underwater. Spinosaurus and Baryonyx were the only two of the non-avian dinosaurs in the study with bones this dense.
“Spinosaurus might also have been a wading animal sometimes, but its ecology is characterized by full immersion in water,” says lead study author Matteo Fabbri, a postdoctoral researcher at the Field Museum of Natural History in Chicago, Illinois. The new findings published in Nature strengthen the case that spinosaurids, the group containing Spinosaurus and its kin, adapted to a life in the water—the only known dinosaurs other than birds to have done so. Recently, for instance, the first fossil ever found of Spinosaurus’s tailrevealed a strange paddle-like shape that the dinosaur may have used to swim.
The 'White Rock Spinosaur' or non formally nicknamed "Vectispinus" On the other hand formally unnamed spinosaur dubbed as ''The White Rock Spinosaurid'', also nicknamed as The "Vectispinus" coming to a closer second; being estimated to be as large as 13.3 meters. Its vertebrae is comperable to S. aegyptiacus in size. Largest estimates for this large theropod around 13.3 meters
Spinosaurus tail vertebrae in comparission to other animals. More similiarities with Basilisk lizards and Sailfin lizards are noticeable.
Although there is counter-evidence that points out the so called 'paddle' Tail wouldn't be able to swim at all; not even being able to stand against the weakest of currents nor rivers or deltas.[36][37]
How much displacement would occur with the long, reclined neural spines in the new Spinosuaurs tail if, as the new paper suggests, it was very flexible. This is really rough work, but it shows how the tail 'unspools' with even limited flexion. To be clear, this isn't a good thing. Tails aren't meant to rip apart when they're flexed. If Spinosaurus had these long, backwards-pointing neural spines, they surely limited flexion, no matter what else the tail verts were doing. This is an issue for the swimming hypothesis.[38]
“The bones don’t lie,” says National Geographic Explorer Nizar Ibrahim, the study’s senior author and a paleontologist at the University of Portsmouth in the United Kingdom. Spinosaurus “is even more aquatic than we anticipated,” he says.
“The bones don’t lie,” says National Geographic Explorer Nizar Ibrahim, the study’s senior author and a paleontologist at the University of Portsmouth in the United Kingdom. Spinosaurus “is even more aquatic than we anticipated,” he says.
Still, exactly how Spinosaurus swam and pursued its fishy prey remains an open question. The prehistoric predator, with its elongated body and gigantic back sail, continues to perplex scientists because it’s so unusual when compared to other aquatic creatures. “While a penguin or a crocodile are capable of swimming and diving underwater, they are also able to walk on land,” Fabbri says.
Spinosaurus aegyptiacus skeletal model Reconstruction. Credit: Randomdinos
Though Spinosaurus and Baryonyx would have had an easier time hanging out in water than other dinosaurs, they also must have come up onto land from time to time. The first known fossil of Baryonyx contains fish scales as well as the bones of a juvenile plant-eating dinosaur—perhaps a sign of the predator’s opportunism both on land and in the water.
Spinosaurid expert Tom Holtz, a paleontologist at the University of Maryland who wasn't involved with the study, says that the new data could have implications far beyond Spinosaurus and Baryonyx. Some paleontologists have suggested that a few types of dicynodonts—extinct two-tusked creatures distantly related to the earliest mammals—could have led hippo-like lifestyles. New bone density analyses could help test these ideas and others like them, especially for fragmentary fossils from which little else is known.
“To my knowledge, no one’s tried this [analysis] on this scale before,” Holtz says. “They will inspire work [and] inform research on what are perhaps to the public less charismatic, but scientifically equally interesting, creatures.”
Spinosauridae 2022 Bone Diagram
Spinosaurus inability to withstand against water currents. Demonstrated.
Beyond Baryonyx and Spinosaurus, the study also took a look at other candidate semi-aquatic dinosaurs, notably the duck-like Halszkaraptor. The team found that none of them had dense, penguin-like bones. However, this does not preclude these animals from a life with ties to the water. Plenty of modern dinosaurs that live around water, such as ducks, geese, and other waterfowl, don’t have penguin-like bone densities.
One of the study’s biggest surprises comes from another spinosaurid species: Unlike Spinosaurus and Baryonyx, a spinosaurid found in Niger called Suchomimus does not have dense, ballast-like bones, despite that animal’s otherwise close resemblance to Baryonyx.
Scott Hartmann's Spinosaurus model with a Tripodal or Bear like 'rearing' position
“One would expect in a group that is not necessarily 100-percent committed to aquatic life the possibility of evolution moving back and forth,” says Holtz. The overall findings underscore just how odd spinosaurids were in the grand scheme of evolutionary history. In most other cases where terrestrial animals adapted to life in the water, the pioneering species tended to have small bodies. According to Holtz, the first mosasaurs ~ a group of ancient, non-dinosaur marine reptiles ~ were no bigger than four to five feet long, about the size of modern Nile monitors. But the progenitors of Baryonyx and Spinosaurus were likely giants.
Paleontologist Kiersten Formoso, a Ph.D. candidate at the University of Southern California, says that while Spinosaurus has dense bones like other land animals that evolved to return to the water, it also “bucks some of the common paths,” evolutionarily speaking.
And then there’s one of Spinosaurus’s hallmark traits: its, enlarged six-foot-tall uncertainly referred as '' dorsal '' Sail.
“I think this animal was perfectly happy chilling and foraging in shallow water with its feet to the bottom in [most] instances,” Formoso says, though in her opinion, Spinosaurus “would have had a difficult time aquatically pursuing prey.”
Still, it’s possible that Spinosaurus’s unique habitat gave the dinosaur an easier time with aquatic hunting. The rock layers that preserved the Morocco Spinosaurus also bear fossils of large, slow-moving prehistoric fish. “Those are the kinds of things that Spinosaurus would have been going after—we’re obviously not talking about going after prey dolphin-style,” Ibrahim says.
3D model and rendering reconstruction of Spinosaurus. Organ placement, anatomical festures and skeletal model indicates that Spinosaurus likely being a wader generalist; not an efficient swimmer or underwater diver as previously thought.
On the other hand the study itself presented criticism; “I don’t doubt that Spinosaurus has very dense bones … [but] is it adding enough mass to help the animals sink?” asks Don Henderson, a paleontologist at Canada’s Royal Tyrrell Museum of Palaeontology whose 2018 study of Spinosaurus suggested that the animal would have been very buoyant.
“If you watch penguins swimming, as soon as they stop flapping their wings, they start to bob up to the surface,” Henderson says. “I just cannot see how Spinosaurus can stay underwater without extreme effort.”
Spinosaurus and Suchomimus skulls comparission. S. aegyptiacus skull noted being more robust compared to Suchomimus by Handerson et.al.
Not every animal with dense bones lives an aquatic or even partially aquatic lifestyle. Elephants and extinct sauropod dinosaurs, for example, have dense limb bones to support their large weights.
However, these weight-bearing “graviportal” bone structures visibly differ from the “osteosclerotic” ones that penguins and other diving creatures have. Highly dense bones can give animals a unique edge when it comes to staying in the water for extended periods without eliminating their ability to navigate dry terrain.[39][40][41][42][43]
Confirmed Spinosaurus specimen's Locations; range from Northernmost areas of Africa to the Central Africa. Note: Several remains detected in far - inland Areas, as well as other locations that are quite away from any major bodies of Water.
The debate continued in the same year with Sereno et al. arguing (also agreeing with the points of Henderson, Dr Hone & Dr Holtz) that it was far too buoyant to dive, an ineffective even slower swimmer and generally unsuitable for aquatic life; also adding the fact that there are several Spinosaurus fossils that have been extracted from the inland Africa; farthest distance from any known deltas, rivers; seas and the oceans.[44][45][46]
The team's developed Spinosaurus model
Additionally the extended tail vertebrae which was also present within neoceratopsians; could presumably serve a similar purpose with the tail appendices of the Basilisk lizards and the Sailfin lizards.
Further adding to the Hone & Holtz, Mr. Handerson's argument; there is another study conducted by Nathan P. Myhrvold, Paul C. Sereno & co. that goes in depth to the theory and the sample analysis published by Nizar et. al. and explains The noticeable errors of using bone compactness and the pFDA for enunciating an entire lifestyle for a clade of Theropods, the Spinosaurids in general.[47][48][49]
Spinosauridae; Carcharodontosauridae and Abelisauridae habitat preferences. Study credits: The “χ” of the Matter: Testing the Relationship between Paleoenvironments and Three Theropod Clades
In addition, correlation and further support with earlier studies; a new study conducted by Stephanie Baumgart et. al. in 2023; found out that the overall evidence isn't strong enough for Spinosurus swimming submerged and diving entirely throughout underwater. Spinosaurus more likely mostly hanged out on the shore. They concluded this study by triying plotting their data points of non-flying non-diving animals & non-flying diving animals, the team has noticed that the 2 groups had lots of overlap. It wouldn’t be easy to draw a line splitting them without a lot of mistaken classifications. [50][4]
Their team has concluded LDA wasn’t the best match for that dataset with so much overlap. But what goes into making the groups in the 1st place? Classifying animals into groups based on behavior may seem simple enough on the surface, but this challenge has plagued scientists for ages. The team's paper asks the : “where do you draw the line between aquatic, semi-aquatic & land animals?” Ex, Camel: spindly limbs, huge foot pads for walking on sand, lives in the desert. Not aquatic. Whale: huge flippers, 100% in water, dies on land, probably hates sand. Aquatic. They wanted to look at something harder: a penguin. Bird people say “aquatic,” it gave up flight to turn its wings into flippers, hunts in water, travels in water.
Although penguins also come up on land to breed, lay eggs, & raise their young. They also travel on land, waddling or sledding. Their team wanted to add spinosaur specimens to the dataset, to see how a wider range of specimens impact the 2022 results. They focused on bone compactness (Cg) of a cross-sectional slice of bone, the ratio of bone area in the slice to the total area of the slice. They used the CT data, bone presence/absence is marked by how radiodense the bone material is. Black in a scan is low density material like air. White is the densest thing in the view, like the densest part of the bone. But lots of variation in density – where to draw the line? [51]
The paper's co-authors and Ms. Stephanie wanted to get a bone compactness (Cg) value of this Spinosaurus bone from CMN, so I sat down with the scan. The trouble was, she wasn’t sure where to set the threshold. She came up with 3 options, all of which looked reasonable, but had a huge range; and then, how much variation is there going to be within an individual? Within species? Between species?
Spinosaurus and Suchomimus bone comparission and review.
We looked at Suchomimus and Spinosaurus leg bones and found quite the range. Which is most representative?
Far too much and too divergent variation is present. Ultimately, given amount of immense variation in specimens and in data collection techniques, they have concluded that previous attributed 'evidence' is not strong enough to put Spinosaurus swimming and diving submerged. Spinosaurus still more likely mostly hung out on shore.[52][53][4]
Several Spinosaurus displaying. Credit: Witton
Dave Hone et. al. additionally pointed out as; there are loads of little things that don't match up well with the idea of it swimming well (and some big ones) and lots of little things that better fit the wading hypothesis and this is one of them. There's rarely a magic bullet of data for stuff like this (though obviously a 4 - 6 ton theropod can't fly etc.) but it should all converge on a point if there's a real ecological signal there and that data simply doesn't converge on swimming. This is more vindication of that point.[54]
Additionally isotopes being rationed and researched; as earlier with the original isotope study; that they found out that it's a key thing that the pro-swimming side keep ignoring. While most of the signatures do point to croc / turtle etc. lifestyles, some have a fully terrestrial one that's inseparable from other regular genuses and species of theropods.[55][32]
Direct Spinosaurid; Baryonychinae Diet Evidence presented by research. Credit: A new theropod dinosaur from the early cretaceous (Barremian) of Cabo Espichel, Portugal: Implications for spinosaurid evolution
So some were spending months at a time on land (estimated tooth turn over of at least 60 days) with a terrestrial food source.[56]
Diet[]
Baryonyx dietary explaination. Credit: Natural History Museum
Direct fossil evidence clearly shows that spinosaurids ate a wide variety of available prey items; both terrestrial and aquatic.
A Baryonyx model and explanation about its generalist carnivorous dietary preferences. Credit: weeklydinosaurs
A Baryonyx specimen was found with scales of the prehistoric fish, most likely Scheenstia, and Bones of a young Iguanodontid in its body cavity.
More Evidence for Spinosauridae generalist carnivorous behavior. Study credits: The “χ” of the Matter: Testing the Relationship between Paleoenvironments and Three Theropod Clades
Moreover, there is another 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. Indicating south american Spinosaurinae were quite similar to their cousins Baryonychinae in terms of dietary preferences.
The case of Siamosaurus feeding on Sauropods gives a more reasonable evidence for the generalist feeding habits and dietary behavior of Spinosaurids and Spinosaurinae subgroup.
Additionally, there has been even more evidence that concluded the spinosauridae as carnivores; such as the Siamosaurus remains been found with direct association with several sauropod remains [57]
The Case of Irritator clearly adds more identifiable evidence to the generalistic and carnivorous behavior of spinosaurid species.
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.
An explaination about the Baryonyx and likely Baryonychinae subfamilies; perhaps all Spinosauridae specimens dietary generalism and behavior. Credit: kirkby teaching
The researchers have proposed that spinosaurines from the formation may have also; opportunistically preyed on terrestrial and aquatic crocodyliforms, same-species juveniles, large turtles, and small to medium-sized dinosaurs. This would have made spinosaurines amongst the top apex predators within the ecosystem.[58]
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.
More official and formal dietary explainations of Spinosaurids
Coincidentally; they also reported that the documented Portuguese Baryonychidae ( formerly identified as iberian Baryonyx now re-established as The Iberospinus ) fossils were found directly associated with several instances of isolated Iguanodon teeth. This situation is noted and than listed as; along with many other such documented associations as another direct support for opportunistic and generalist, carnivorous feeding behaviour in spinosaurs.[59]
The description of the Japanese Spinosaurid (an unclarified species and genus of Spinosaurid ) hunting and subduing a crocodylimorph. Artwork done by artist Palaeotaku
Another direct and well documented evidence, has been discovered at 2016. The 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 direct 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 vague Ostafrikasaurus. If this identification is correct, The MUPE HB-87 specimen represents the oldest known evidence of spinosaurids in the fossil record. Along with presenting the oldest record for generalist carnivorous behavior in the whole genera of Spinosauridae. Based on this specimen, the authors proposed a new evolutionary model for the transition between "normal" theropod teeth, to those of spinosaurid features.[1][60] However; similar to Ostafrikasaurus; this specimens overall attributions remains unclear; as some other studies connected the teeth remains to the wider general of Megalosauridae.[61][62]
Private Carcharodontosaurus vertabrae showing several bitemarks directly attributed to Spinosaurus
Additionally there is a ( potential of being highly illicitly manipulated ) private collection fossil; a large vertabrae; belonging to aCarcharodontosaurid ( not Carcharodontosaurus itself as no vertebrae can be reliably assigned to this genus so far) showing signs of being consumed by what appears to be a Spinosaurus. The vertabrae showing several bitemarks amd even inlaid teeth. Its unknown if this represent an interspecies conflict, aggression; scavenging or else.
Although it should be mentioned that those do not appear to be regular fossilized "pathologies" as these carves look rather fresh, therefore these effects could possibly have the potential of being carved into the bone on purpose, which is not an unusual practice in the fossil black market. Further research is; quite unfortunately; highly unlikely because of the aforementioned specimen is no longer viable for public and has been bought. The spinosaurinae could be a Sigilmassasaurus either; albeit its more unlikely due indeterminate size of this theropod compared to Carcharodontosaurus.
Bite Force[]
Spinosaurus life sized skull reconstruction
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 theropods maximum size.[63]
a comparission of Spinosaurus skull to a crocodilian ( An Alligator in this specific case )
Another study referred to as, Feeding Mechanics in Spinosaurid Theropods and Extant Crocodilians; indicates that the Spinosaurids have had a noticeable bite force. The researches have concluded that the bite force of Suchomimus may have been comparable to alligators, thus demonstrating that the Spinosaurids were likely able to capture terrestrial animals[64]
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 small to medium sized prey with the rosette of teeth at the front of the jaws, and finished it by shaking it.
The '' Megatheropods '' size comparission (Credit: Randomdinos, Dan Folkes).
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.[65] Thus this feature would enable the theropod to subdue its potential prey.
Up-to-date studies confirm that spinosaurids had a rather weak bite force compared to other theropods. Rowe and Snively (2021) estimated a bite force of 4.037 Newton for Suchomimus tenerensis, which is half as strong as the significantly smaller Allosaurus fragilis (9.389 Newton; Sakamoto 2022). Spinosaurus aegyptiacus bite force was estimated 11.936 Newton (Sakamoto 2022), which is also weaker than theropods of comparable size, such as Giganotosaurus carolinii (24.977 Newton; Rowe et al. 2021).
Despite the biteforce is weaker than anticipated; it would still be more than enough to subdue any viable prey items as there are several predatory and opportunistic animals today; with much more weaker bite force that hunt various prey items. Although study concluded that Spinosaurus biteforce is still more compotent; especially when compared to the likes of some medium to larger sized theropods such as Allosaurus, Xuanhanosaurus, Ceratosaurus, Majungasaurus, Metriacanthosaurus, Sinraptor, Megalosaurus, Rajasaurus, Aucasaurus, Megaraptor, Chilantaisaurus, Deltadromeus, Rapator, Raptorex and many other such theropods that were certainly predatory carnivores.
Artist's Interpretation Irritator hunting, by unhinging its jaws.
A new study establishes a case for the Irritator; and presumably Spinosaurinae members or presumably all Spinosaurids; could be able to 'unhinge' their jaws to a structure similar to Pelicans; or some modern snake species.[66] If this anatomical feature is validified; this would allow spinosaurids to shallow a wide variety of prey items; both aquatic and terrestrial. Similar to how several predatory wader avians do it. Such as Skuas, Seagulls; Pelicans; petrels, jaegers as well as several species of literal snakes; including larger boid snakes perform a similar strategy for prey capture. Meanwhile this discovery often portrayed as a revelation for a directly piscivorous lifestyle; many proclaimers often forget about the fact that most modern animals that has such jaw extensive capabilities are rather voracious and gluttonous generalists and are certainly not picky when it comes to their viable prey items. For example that the pelicans are rather notorious generalists[67][68][69][70][71][72][73][74] Additionally; several species of middle to larger sized seagulls show clear preference for overt generalism; as well. Experts even calling hunting seagulls a regular even normal occurance on habitats.[75][76][77] The other aforementioned animals and avians; with jaw unhinging or extending abilities are well recorded predators; such as skuas, petrels; Largest boid and variant snake species; as well as The opportunistic and kleptoparasitic jaegers.[78][79][80][81][82][83][84][85]
A further Study also concluded that there is not evidence that the Spinosaurids were neither obligate piscivores nor exclusively confined to aquatic prey. Scientist team observed the craniodental morphology of Spinosauridae and compare it to modern Crocodilia.
They measured from spinosaurid and crocodilian skeletal material the area of alveoli as a proxy for tooth size to determine size-heterodonty. Geometric morphometrics were also conducted on tooth crowns and tooth bearing regions of the skull. The team also look at the Spinosaurids craniodental morphology and compare it to modern Crocodilia. They measured from spinosaurid and crocodilian skeletal material the area of alveoli as a proxy for tooth size to determine size-heterodonty. Geometric morphometrics were also conducted on tooth crowns and tooth bearing regions of the skull. Spinosaurids overall had relatively large alveoli, and both they, and crocodylians, had isolated regions of enlarged alveoli. Spinosaurines also had enlarged alveoli along the caudal dentary that baryonychines lacked, which instead had numerous additional caudal tooth positions.
The Size-heterodonty was positively allometric, and spinosaurids overlapped with generalist/macro-generalist crocodilians of similar sizes. Spinosaurid crown shape morphologies overlapped with certain slender-longirostrine crocodilians, yet lacked molariform distal crowns typical of most crocodilians. Spinosaurid rostra and mandibles were relatively deep with undulating margins correlating with local tooth sizes, which may indicate a developmental constraint.
The Spinosaurines had a particularly long concavity caudal to their rosette of anterior cranial teeth, with a corresponding bulbous rostral dentary. The spinosaurid feeding apparatus was well suited for quickly striking and creating deep punctures, but not cutting flesh or durophagy. The jaws interlocked to secure prey and move it deeper into the mouth.[86]
The baryonychines probably did little oral processing, yet spinosaurines could have processed relatively large vertebrates. Overall, there is essentially no indication that spinosaurids were restricted to fish or small aquatic prey. They had relatively large alveoli, and both they, and crocodylians, had isolated regions of enlarged alveoli. Spinosaurines also had enlarged alveoli along the caudal dentary that baryonychines lacked, which instead had numerous additional caudal tooth positions. Size-heterodonty was positively allometric, and spinosaurids overlapped with generalist/macro-generalist crocodilians of similar sizes.[87][87]
Spinosaurid crown shape morphologies overlapped with certain slender-long crocodilians, yet lacked molariform distal crowns typical of most crocodylians. Spinosaurid rostra and mandibles were relatively deep with undulating margins correlating with local tooth sizes, which may indicate a developmental constraint. Spinosaurines had a particularly long concavity caudal to their rosette of anterior cranial teeth, with a corresponding bulbous rostral dentary.[88]
The spinosaurid feeding apparatus was well suited for quickly striking and creating deep punctures, but not cutting flesh or durophagy. The jaws interlocked to secure prey and move it deeper into the mouth. The baryonychines probably did little oral processing, yet spinosaurines could have processed relatively large vertebrates. Overall, there is essentially no indication that spinosaurids were restricted to fish or small aquatic prey.[89][90]
Interspecies Conflicts[]
Its unknown how the Spinosaurids have interacted with other spinosaurids; other theropods and crocodylimorphs as well as other animals. There are some fossil records however; that might indicate that interspecies conflicts have had occured.
Illustration of Irritator attacking and capturing a Pterosaur
In the case of Irritator. Its known that its teeth found directly embedded onto a large pterosaur. Although its unclear if it represents a true attacking event.[91]
In the case of Siamosaurus. The fossil remains found to be directly linked and embedded with sauropod remains. Its unclear if it represents a true predation event; scavenging or both.[92]
Baryonyx feeding on an Iguanodont. Creeditsy: simonmoberg
* In the case of Baryonyx; its body cavity contains both fish and remains belonged to subadult Iguanodonts.[93]
Furthermore Spanish Baryonychinae fossils; whether categorically belonged to Baryonyx or Iberospinus found directly associated with more Iguanadontid remains.[59]
The Presumably Spinosaurus sail injury featured in BBC's Planet Dinosaurs documentary
▪︎ In case of Spinosaurus; which its habitat ( Middle to Late cretaceous north and central Africa ) quite essentially referred as '' The most dangerous place on earth '' by paleontologists.[94][95][96][97][98]
The presumably injured Spinosaurus vertabrae in comparission to a regular sail vertabrae. Featured in: BBCs Planet dinosaurs
Because of sheer abundancy Carnivorous, Predatory animals. Such as small to medium sized - to absolutely gigantic Theropods; several species of large crocodylimorphs, as well as sauropods and several other species. There are instances of fossil remains that might potentially represent an interspecies conflict had occured.
A sample of Carcharodontosaurus vertabrae belonging to a Private Collection ~ Spinosaurus teeth directly embedded within it.
One highly noticeable example being a presumably damaged sail vertabrae that featured within BBC's Planet Dinosaur documentary series that suspected to be enacted by a Carcharodontosaurus. Althought it remains unclear if this; too was a scavenging event or direct aggression.
Another sample from a Carcharodontosaurus vertabrae belonging to a Private Collection; with Spinosaurus teeth embedded within the inner part of the specimen
Whereas another instance being a Carcharodontosaurid vertabrae which shows several bitemarks embedded onto it by a Spinosaur; even a Spinosaur teeth directly bedded within in. Albeit it remains unclear if these "pathologies" were carved into the bone on purpose; as it is not unusual to manipulate bones in private collections and black markets to gain more profit; or are actually legitemate.
Although these events are rather expected; regular even especially in relation to modern African habitats where several large carnivorous animals; such as several crocodile species ( Nile crocodiles being most commonplace ), several large felids ( cheetahs, lions; leopards ) additionally giant phythons, wild dogs; many larger avian species; as well as larger species of fish do indeed directly compete with each other.
Interspecies conflict is a common occurance in modern habitats of Africa; even south America ( Which its climate was much closer to Middle - Late cretaceous of Africa ) thus a similar reasoning can be made about the habitat containing several species of large to giant theropods ( Carcharodontosaurus species, Deltadromeus; enigmatic Bahariasaurus; an unnamed species of 10.5 meters abelisaurid; Rugops; unnamed and unidentified dromaesaurids; enigmatic Sigilmassasaurus and such ) , larger species of Crocodylimorphs and many other large species of animals; including herbivorous sauropods.
Well known, Official Members of the Spinosauridae family: Spinosaurus, Oxalaia, Suchomimus, Baryonyx, Ichthyovenator, and Irritator. Artwork by: USIK
Some members of Spinosauridae family. In order smallest to largest: Vallibonavenatrix, Baryonyx, Riparovenator, Protathlitis, Suchomimus, Spinosaurus. Credit: CheeseCakeofPluto
3 'megatheropods' ( Credit: miyess dan folkes, serano )
Three Colossal theropods from the same formation: Spinosaurus; Bahariasaurus and Carcharodontosaurus
Depiction of interpreted Spinosaurid Jaw capabilities
Realistic Spinosaurus head Reconstruction
Spinosaurus reconstruction by: Ivan iofrida. Pictured with a Juvenile ( a claw fossil identified as a Spinosaurus juvenile )
Spinosaurus reconstruction by robertfabiani
The three infamous 'megatheropods' : Spinosaurus, Carcharodontosaurus and Tyrannosaurus
Spinosaurus reconstruction by HypotheticalGabe.jpg
Spinosaurus specimens ( MSNM-V & FSAC K-K Subadult") by Gabriel Ugueto
Another diagram of fhe large Theropods
Spinosaurus reconstructed on a Tripodal / rearing up posture similar to modern Ursids ( bears )
Up-to-date Spinosaurus model by PNSO
Modern Spinosaurus by Mark Witton
Suchomimus skeletal model by Dan Folkes
Icthyovenator by Joschua Knuppe
3D replica of S. aegyptiacus skull
Spinosaurus hunting ashore. Credit: unknown
Longer snouted crocodilian species bear some noticeable similiarities to Spinosauridae species
Suchomimus Skull
Sailfin lizard live model and skeleton. Bearing noticeable resemblance to Spinosaurinae enlarged tail vertabrae along with the Neoceratopsia tails
3D reconstruction of Spinosaurus skull
Spinosaurus skull 3D replication
Cast of Spinosaurus skull
Detailed inacriptions about Spinosaurus skull
Pre-2023 Spinosaurus render. Credit:
Serano's modern Spinosaurus models
Spinosaurus represented in BBC's Planet Dinosaur
Spinosaurus modern 3D model
Modern Spinosaurus model by Cisiopurple
Spinosaurus skull cast
Spinosaurus hunting throughout the Swamps
The Original Spinosaurus specimen
Spinosaurus standing in a river
Earlier Spinosaurus reconstruction represented in BBC's Planet Dinosaur
Spinosaurus sprinting
Spinosaurus wading throughout waterways/riverbed. Credit: durbed
Spinosaurus modern model
Spinosaurus modern model. Credit: Mario Lanzas
Spinosaurus sculpture
Spinosaurus reconstruction
Spinosaurus size diagram
Resting Spinosaurus. Credit: Joschua Knuppe
Vallibonavenatrix model / diagram
Vallibonavenatrix Reconstruction ( albeit it is unknown if it had extensive tail vertabrae similiar to distant Spinosaurinae/sailfin lizards/basilisk lizards/neoceratopsians )
Modern Reconstruction of Oxalaia
Baryonyx Reconstructions
Sigilmassasaurus model and render
Sigilmassasaurus model from known elements and attributions
Siamosaurus live-model
Kmown elements/remains of "Vectispinus" or White Rock Spinosaur . Original vertebrae are comperable to Spinosaurus itself.
Riprovenator and Ceratasuchops
Protathlitis reconstruction
Irritator Skull
BSP 1912 Holotype size comparission. Credit: Petite Paleoartist or Sauriazoicillus
Icthyovenator size comparission
"Vectispinus" or The White Rock Spinosaurid illustration
Spinosaurus aegyptiacus reconstruction by vimmemoriaeuniversum
Spinosaurus resting. Credit: Stievens art site
Spinosaurus in Bahariya habitat
South American Spinosaur; Specifically Spinosaurinae Specimens. Including Irritator and Angaturama Holotypes. The combination of these specimens might potentially represent a whole new genus on its own.
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