(CNN)Unlike most dinosaurs, it seems that spinosaurs liked the water.
This suggestion is based on the analysis of a well-preserved fossil tail of Spinosaurus aegyptiacus, published Wednesday in the journal Nature.
Spinosaurs were a unique group of large-bodied theropods historically interpreted as nearshore waders that fed on fish along the margins of bodies of water.
Bigger than both Tyrannosaurus rex and Giganotosaurus, they lived during the Cretaceous era -- between 145.5 and 65.5 million years ago. That was the last period of the Mesozoic Era following the Jurassic Era, ending with the extinction of dinosaurs (except for birds).
An almost complete tail from a subadult Spinosaurus was found in the 95-million-year-old Kem Kem Beds on the northwestern edge of the Sahara Desert in southeastern Morocco, the researchers said. The tail helped Spinosaurus to move through and hunt in water.
Historically, Spinosaurus was known only from incomplete fossils. The only other associated specimen to be discovered was destroyed during World War II.
Previous research on non-avian dinosaurs suggested these animals were restricted to dry land environments, and proposals that some groups lived in aquatic environments were considered controversial and were abandoned decades ago.
In a 2014 study, some of the same researchers identified a series of adaptations in the largest known spinosaurid, S. Aegyptiacus, that would have supported a semiaquatic lifestyle. They included reduced hind limbs, wide feet with large flat toe bones and long bones that were dense but good for buoyancy. What's more, S. Aegyptiacus had a suite of cranial features such as crocodile-like teeth and jaws, and a nose suited for diving.
How Spinosaurus moved through water was still unknown.
The discovery was, "in many ways, a dream come true, because as a scientist you're always hoping to make a discovery that is really going to change at a fundamental level how people think about a discipline -- in this case, paleontology," said lead author Nizar Ibrahim, an assistant professor of biology at the University of Detroit Mercy in Michigan.
Evidence lost to international warfare
Associated specimens of Spinosaurus were described in the early 20th century by pioneering and legendary German paleontologist Ernst Stromer. Stromer unearthed bones in a different part of the Sahara desert in Egypt, and had them on display at the Bavarian State Archaeological Collection in Munich, Germany.
"At the time, that was actually one of the best and largest natural history museums in all of Europe," Ibrahim said.