Larger even than some Tyrannosaurus and Giganotosaurus, this fellow weighed up to 21,000 kg and with all that mass was still an accomplished swimmer.
The genus was known first from Egyptian remains discovered in 1912 and described by German palaeontologist Ernst Stromer in 1915.
The original remains were destroyed in World War II, but additional material came to light in the early 21st century. It is unclear whether one or two species are represented in the fossils reported in the scientific literature. The best known species is S. aegyptiacus from Egypt, although a potential second species, S. maroccanus, has been recovered from Morocco.
The contemporary spinosaurid genus Sigilmassasaurus has also been synonymized by some authors with S. aegyptiacus, though other researchers propose it to be a distinct taxon.