Sigilmassaurus: Did it exist or was it a bigger Spinosaurus?

Sigilmassasaurus, was found in 1996 in the and was named Sigilmassasaurus ‬brevicollis which means '"short neck". Two years late, in 1998, Sereno et al classified Sigilmassasaurus to be synonymous with Carcharodontosaurus(shark toothed lizard), a member of the carcharodontosaurid family, which also consists of Giganotosaurus(giant southern lizard), Acrocanthosaurus(high-spined lizard) and others. The reason for this was due to similarities with a Carcharodontosaurus skull described in 1996. Another fossil that was labeled "Spinosaurus B" was also declared synonymous with Carcharodontosaurus.

However, later studies revealed big differences between the fossils and that meant that Sigilmassasaurus was no longer synonymous with Carcharodontosaurus. A report in 2005 by Novas et al detailed this and also declared tail vertebrae first thought to be of Sigilmassasaurus to be of iguanodont origin. Another report was also made in 2013 by McFeeters et al.

One year later after the report by McFeeters et al, Ibrahim et al that "Spinosaurus B" and Sigilmassasaurus were actually fossils of Spinosaurus(spined lizard). Sigilmassasaurus was specifically classified as S. aegyptiacus. However the reconstruction was based on isolated remains which led to countless doubts, questions and hot debate especially among researchers. 2015 and Evers et al classified Spinosaurus and Sigilmassasaurus as separate species and not as one genus. It went one step further to say that S. maroccanus‭, was possibily a synonym to Sigilmassasaurus. This stuck for five long years until 2020 came. That was when Symth et al conducted a study with the conclusion of Sigilmassasaurus being synonymous to Spinosaurus aegyptiacus. 

Until further research, for now all I can say is that it was synonymous with Spinosaurus.

References:

https://www.prehistoric-wildlife.com/species/s/sigilmassasaurus.html