Spinosaurus based on the proposed tripod stance and pelican like posture.
Basic info on Spinosaurus: Length: 49ft (15 meters) Weight: 6-7 tons Height: around 20ft Name meaning: Spine lizard Location found: Bahariya formation, Western Egypt
Spinosaurs has gained quite an uprising in popularity since it was discovered, however despite how well known it is, the remains we have of this animal are in scarcity. Nonetheless as we begin to discover more remains of this dinosaur it's exact appearance becomes stranger and stranger and in recent years it has become a bit of a paleontological oddity(more so than previously). Previous reconstructions had originally portrayed Spinosaurus as a large long legged bipedal predator, but in 2014 new remains gave Spinosaurs a complete makeover. The study found that in relation to its body, Spinoisaurus had surprisingly short legs and slightly more irregular shaped sail, as opposed to previous reconstructions that portrayed Spinosaurus with a semi-circular sail. Furthermore to add with this unusual and striking discovery was an equally odd (and controversial) proposal on the animal's locomotion. Based on the new leg estimates it was first proposed that Spinosaurus may have been a quadruped, using its robust arms to support its massive girth, however this proposal soon came under harsh criticism. The main issues with the quadrupedal theory was that theropod hands (especially the wrist) were not flexible enough to bend to the extent that would be needed for Spinosaurus to hold a quadrupedal ("knuckle-walking")stance, nor were the arms well suited enough to support the weight of the 6-7 ton animal. For these reasons the quadruped theory's credibility has been highly doubted, as no direct remains of the arms showed specialization for a qaudrupedal posture. The exact locomotion of this animal is uncertain and since then many other theories have been proposed from belly sliding to even awkwardly “waddling” on land. Other proposed forms of locomotion are that Spinosaurus may have had to use its tail as a counter-balance(or a more upright stance) in order to maintain its center of gravity, hold its neck in an almost “pelican” like posture, or that the bird-like air sacs within its body would've helped it balance. Nevertheless aside from locomotion on land the most interesting attribute of Spinosaurus was its semi-aquatic lifestyle, making it one of the first known dinosaurs to posses such clear adaptations for it . Unlike most other theropods, Spinosaurus was perfectly suited for life in the water, using its short yet robust legs to swim through the wetlands and rivers it inhabited. In striking contrastment to Spinosaurus enabling the ability of swimming, its been recently proposed that because of the sheer density of its bones swimming may have been unlikely. With this it’s become likely spinosaurus may have moved through the water similar to modern hippos (which themselves lack the ability to properly swim and stay afloat) and may have instead treaded along the riverbed and used its legs to thrust itself through the water. Additionally Spinosaurus was clear and almost exclusive fish hunter, sticking its enormous jaws into the water in hopes of snagging any fish passing by. Analysis of the premaxilla of Spinosaurus shows an arrangement of holes similar to those seen on modern day crocodiles, which were likely pressure sensors, which helped spinosaurus sense the slightest of vibrations in the water and detect the presence of fish or other suitable prey items. Another great mystery concerning Spinosaurus has been its iconic sail, previously it was thought to aid in controlling body temperature, however the neural spines lack any indications of condensed blood vessels that would be needed if the sail served such a purpose. As well other paleontologist have said the sail was likely a fatty hump, but just like the temperature control hypothesis the sail lacks any bone textures that would be made by ligaments if the sail had been used for storing fat, the exact use of the sail is yet another mystery to Spinosaurus and up to debate. Now the biggest question is why would such an animal have all these strange features and adaptations? The simplest answer is that Spinosaurus may adapted to a more aquatic lifestyle in order to avoid direct competition with the other theropods that it shared its environment with or take advantage of the abundance in marine prey. At the time Spinosaurus lived, Africa had a surprisingly large variety of large theropods, from Carcharadontosaurus to Bahariasaurus, yet very little prey animals in comparison. Since there was very little prey on land Spinosaurus instead specialized itself to a more crocodilian/ bear niche, where it could prey on the surplus of large fish and marine life, while avoiding any conflict or direct competition with the more land-based theropods.