Spinosaurus

Credit: PaleoGeek on the Wikimedia Commons.

*Spinosaurus* is an extinct genus of large spinosaurid theropod dinosaur that lived in North Africa from the Early to Middle Cretaceous, and possibly to the Late Cretaceous.

## History

    BSP 1912 VIII 19, the holotype, was described by Stromer (1915) from the Bahariya Formation. It consists of right and left dentaries, splenials, a straight maxillary fragment (which was not illustrated), 20 teeth, 2 cervicals, 7 dorsals, 3 sacrals, 1 caudal, 4 thoracics and gastralia. The mandible was 75 centimeters (30 inches) long, and the longest neural spine was 1.65 meters (5.4 feet) long. Stromer claimed an early Cenomanian age. "During the night of 24/25 April 1944 in a British bombing raid of Munich", the Paläontologisches Museum München was struck and the holotype specimen was destroyed. However, illustrations and photos remain, and Stromer's son donated his father's archives to the museum in 1995. Smith et al. analyzed 2 photographs, and found that the original illustrations were slightly inaccurate based on a photo of the mandible and entire specimen mounted. Rauhut (2003) suggested that it was a chimera consisting of some carcharodontosaurid vertebrae and neural spines cf. *Acrocanthosaurus* and a *Baryonyx*/*Suchomimus* mandible. This was soon rejected. The name *Spinosaurus* means spine lizard in Latin. A documentary by National Geographic briefly shows pictures of the holotypic crania and postcrania that differ from known images.

## Description

    The holotype is roughly 3 meters tall and 9.96-10.5 meters long, being at the lower end of the spinosaurine range. The skull was narrow with straight conical teeth, with 6-7 on each side of the premaxilla and 12 in the both maxillae. The 2nd and 3rd teeth are longer, creating a space between them and the maxillary teeth. The premaxilla was expanded. Using spinosaurine rostra (including the holotype), the skull was likely around 1.6-1.68 meters long, but this is variable in spinosaurids and specimens included in the estimation may be from other taxa. The neck was long, muscular and sigmoid. The large hooked claws were on heavy fingered arms. The thumb was the largest. The neural spines were very large, and no consensus has been reached on their arrangement (and thus sail shape) in life. These spines are constructed differently than other sail-backed animals. The tail was likely also sail-backed.

## Paleobiology

### Diet

    Its unspecified that if the *Spinosaurus* was whether a highly derived, specialized piscivore or a generalist carnivore. All known evidence for Spinosaurinae dietary preferences, directly comes from the relative Spinosauridae species, for example; *Baryonyx* had shown clear indication for generalist behavior, as one specimen's fossilized stomach contained a juvenile *Iguanodon* ; as well as specimens from İberian peninsula has also associated with *Iguanodon* teeth. A Spinosaurinae, a closer relative to *Spinosaurus*, *Irritator* that either attacked, or ate a large pterosaur. *Irritator* had been suspected to be the apex predator of its environment . As well as the aforementioned fossil specimens, there has been another recent discovery of another Spinosaurinae, a south Asian spinosaurid known as *Siamosaurus*, that has been directly consumed sauropods. It is uncertain that if this event was a scavenging situation or a true hunting behaviours . There is also another discover that could be directly linked to the Spinosauridae generalism. In 2016, Spanish palaeontologist Aleandro 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. The tooth is oval in cross section, is recurved, and bears small serrations, as well as strong fluting that does not reach the tip of the crown. Thus indicating the generalist carnivorous behavior might be prevalent through the Spinosauridae family from their very beginning. Based on these paleontological discoveries, *Spinosaurus* could have been a generalist predator that hunted variety of animals such as the massive multi-ton fish, like *Mawsonia* and *Onchopristis*, aquatic semi-aquatic and terrestrial crocodylimorphs, as well as animals such as larger pterosaurs and small-to-medium sized dinosaurs. Information published by Holtz and Hone in 2021 cites numerous anatomical intricacies as evidence for *Spinosaurus* acting like a generalist wading avians, like shoebills, pelicans, skuas or giant petrels rather than aquatic species of mammals, or crocodilians such as gharials. A vertebrae of Carcharodontosaurus have confirmed to have *Spinosaurus* bites and even an inlaid *Spinosaurus* teeth is also known. If this fossil is actually validated, it proves that the *Spinosaurus* did eat and/or attacked other dinosaurs, even other theropods.

## Paleoecology

The Bahariya Formation carried other predatory megatheropods, such as *Bahariasaurus*, *Carcharodontosaurus* and *Deltadromeus*. *Paralititan* and *Aegyptosaurus*, crocodylomorphs, bony and cartilaginous fish, turtles, lizards and plesiosaurs are also known. Pterosaurs were likely preyed on in the dry season. Similar to the Morrison Formation, niche partitioning made large megatheropods compatible in the same region, to a degree similar to the modern African savanna.

## Notable Specimens

* "EMB1MORO": A specimen which has been suggested to be a *Spinosaurus* embryo, given the informal name "S. dorsojuvencus" by C.E. Goo, who is known for the Petrified Embryology series. The author suggests cervical scutes are present. However, the specimen, collected in Morocco, is likely not a Spinosaurus, and probably not even animal remains at all. Most paleontologists dismiss these, as they appear to be a product of pareidolia rather than genuine fossils.
* NMC 41852 or NMC 42852 : a humerus, claimed by Cau et. al to be comparable to *Limaysaurus* and placed it as a a rebbachisaur, later determined by Ibrahim et al. (2014) to be a spinosaur affinity. If its assignment to *Spinosaurus* is confirmed, it would extend the weight limit of the theropod even more, 10+ tons.

## Gallery

### Reconstructions

*Spinosaurus* attacking a crocodylomorph.
**Credit: Batavotyrannus.****Credit: Fred Wierum.****Credit: Lindsey Wakefield.****Credit: HypotheticalGabe.****Credit: Patrik Oberstar.****Credit: DinoEsculturas.****Credit: Miles1314520.****Credit: SmallMicroraptor on DeviantArt.**
### Fossils and Skeletons

A vertebrae of *Carcharodontosaurus* have inlaid *Spinosaurus* teeth.A vertebrae of *Carcharodontosaurus* have inlaid *Spinosaurus* teeth.
### Diagrams

NMC 41852.**Credit: SpinoInWonderland.***Spinosaurus* compared to *Baryonyx* skull.**Credit: Vimmemoriaeuniversum.***S. aegyptiacus* holotype.
**Credit: Olof Moleman.**

## References

1. ↑ https://archive.org/details/g.s.paul2016theprincetonfieldguidetodinosaurs/page/n87/mode/2up
2. ↑ 2.0 2.1 2.2 https://twitter.com/Manu\_MB13/status/1599396971474694145
3. ↑ https://onlinelibrary.wiley.com/doi/abs/10.1111/1475-4983.00181
4. ↑ 4.0 4.1 4.2 https://en.wikipedia.org/wiki/Spinosaurus
5. ↑ https://twitter.com/TheBioBob/status/1476634976321998856
6. ↑ https://www.nhm.ac.uk/discover/how-did-baryonyx-change-what-we-knew-about-spinosaurs.html
7. ↑ https://www.nature.com/articles/430033a
8. ↑ https://paleorxiv.org/mjt95/
9. ↑ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4734717/
10. ↑ 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
11. ↑ https://twitter.com/ivankay17/status/1354002825219624960
12. ↑ https://ancient-life.quora.com/Carcharodontosaurus-vertebra-with-bite-marks-Theropod-Pathology
13. ↑ https://lzcuflsmugrezuex.quora.com/Ive-heard-about-a-Spinosaurus-tooth-being-embedded-in-a-Carcharodontosaurus-vertebra-is-it-true-If-it-is-can-I-see-a
14. ↑ https://petrifiedembryology.wordpress.com/petrified-embryology-volume-3-the-frozen-baby-dinosaurs-spinosaurus-dorsojuvencus/
15. ↑ https://www.science.org/doi/abs/10.1126/science.1258750