Spinosaurus

***Spinosaurus aegyptiacus (spin·o·saur·us/pronounced SPINE-oh-SORE-us)*** ("spine lizard") is a species of large spinosaurid theropod dinosaur, that inhabited the early to middle Cretaceous northern Africa (about 112 mya - 93.5 mya). It is one of the largest known theropod dinosaurs.

## Description

Spinosaurus was a large species of theropod that has belonged to the family of Spinosauridae. The current estimations for Spinosaurus suggest a length estimation between 15 to 16 meters long, 5 to 7 meters tall and weighted between 6.5 to 7.5 tonnes. The most well known anatomical feature of this animal is the elongated spines on its back. The theropod had a crocodylian like elongated face, large arms; long body, and, possibly; elongated and dense tail.

## Paleobiology

The main scientific consensus for Spinosaurus, establishes that this theropod was likely a semi aquatic animal. This conclusion has been established by the 2014 fossil discoveries that gave Spinosaurus highly differentiated anatomical features [2], this conclusion has been bolstered by recent discovery as a highly elongated and dense tail, that might, potentially; helped animal to swim against the current of the Rivers.

In addition; there are conducted research that refutes the semi-aquatic thesis for Spinosaurus, such as; a 2018 research, done by paleobiologist Donald Henderson, the research has studying the buoyancy in lungs of crocodilians and comparing it to the lung placement in Spinosaurus, it was discovered that Spinosaurus could not sink or dive below the water surface. It was also capable of keeping its entire head above the water surface while floating, much like other non-aquatic theropods. Furthermore, the study found that Spinosaurus had to continually paddle its hind legs to prevent itself from tipping over onto its side, something that extant semi-aquatic animals do not need to perform. The research conducted that Spinosaurus probably did not hunt completely submerged in water as previously hypothesized, but instead would have spent majority of its life on land or around water [4][5][6] however; these studies of the tail vertebrae of Spinosaurus refute Henderson's proposal that Spinosaurus mainly inhabited areas of land near and in shallow water and was too buoyant to submerge. Studies of the tail, specimens recovered and analyzed by Ibrahim, Pierce, Lauder, and Sereno, in 2018 indicate that Spinosaurus had a keeled tail that was well adapted to propelling the animal through water. The elongated neural spines, which run to the end of the tail on both dorsal and ventral sides, indicate that Spinosaurus was able to swim in a similar manner to modern crocodilians. Through experimentation by Lauder and Pierce, the tail of Spinosaurus was found to have eight times as much forward thrust as the tails of terrestrial theropods like Coelophysis and Allosaurus, as well as being twice as efficient at achieving forward thrust. This discovery indicates that Spinosaurus may have had a lifestyle comparable to modern alligators and crocodiles, that this animal might have capable of remaining in water for long periods of time while hunting. [7] In addition; there is also the research conducted at 2010, the scientists directly looked to the oxygen isotope ratios of spinosaurid bones, by comparing 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. However; Siamosaurus specimens tended to have the largest difference from the ratios of other theropods. Spinosaurus tended to have the least difference, this strongly suggests that the different species of Spinosaurids have had differentiated preferences for their habitats. Spinosaurus specimens show similar isotope ratios to other terrestrial theropods. This meant different species of spinosaurids have had differentiated habitat preferences

Additionally there are a number of counter thesis against the extended tail spines usage for propolsion, and in water; as well

The debate whether that the Spinosaurus was entirely aquatic, terrestrial or amphibious, switched between both habitats, will continue to be a matter of debate.