In Depth
Sigilmassasaurus has had a turbulent taxonomic history, at times being valid, other times being synonymous with other genera, to being valid again. It all began in 1996 when Dale Russel described a series of cervical vertebrae that were noted for being fairly short, hence the type species name S. brevicollis which mans ‘short neck’. In 1998 Sigilmassasaurus was declared synonymous with Carcharodontosaurus by Sereno et al upon the basis of similarities to a Carcharodontosaurus skull that they described in 1996. Also in 1996 Sereno et al declared fossils labelled as ‘Spinosaurus B’ as synonyms to Carcharodontosaurus upon the basis of similarities of the neck vertebrae.
However later studies of Sigilmassasaurus and ‘Spinosaurus B’ material have revealed stark differences between them and known Carcharodontosaurus fossils, meaning that they cannot be synonymous with Carcharodontosaurus. These conclusions were published in reports in 2005 (Novas et al) and 2013 (McFeeters et al). The 2005 report by Novas et al also revealed that additional caudal (tail) vertebrae assigned to Sigilmassasaurus by Russel actually belonged to iguanodont dinosaurs, making Sigilmassasaurus only known from cervical vertebrae.
The next big revision came with the 2014 re-description of Spinosaurus by Ibrahim et al which concluded that Sigilmassasaurus and ‘Spinosaurus B’ represented further material of the Spinosaurus type species S. aegyptiacus. The Ibrahim et al reconstruction however has been a controversial matter specifically for the reason that they reconstruction of Spinosaurus was based upon the isolated remains of many different individuals leading some researchers to question the validity of some of their claims. Indeed, it was only one year later in 2015 that a new study by Evers et al concluded that the Sigilmassasaurus fossil material was not synonymous with Spinosaurus but was indeed its own spinosaurid dinosaur genus. Further to this the study went on to suggest that a controversial species of Spinosaurus, S. maroccanus (often treated as synonymous with S. aegyptiacus) was a possible synonym to Sigilmassasaurus. Since this a later study in 2020 (Symth et al) suggested that Sigilmassasaurus is actually synonymous with Spinosaurus.
Further Reading
- Isolated dinosaur bones from the middle Cretaceous of the Tafilalt, Morocco. - Bulletin du Mus�um National d’Histoire Naturelle, Paris, S�rie 4 18: 349–402. - Dale Russel - 1996. - Predatory dinosaurs from the Sahara and Late Cretaceous faunal differentiation. - Science 272: 986-991. - P. C. Sereno, D. B. Dutheil, M. Iarochene , H. C. E. Larsson, G. E. Lyon, P. M. Magwene, C. A. Sidor, D. J. Varricchio & J. A. Wilson - 1996. - A long-snouted predatory dinosaur from Africa and the evolution of spinosaurids. - Science 282 (5392): 1298–1302. - P. C. Sereno, A. L. Beck, D. B. Dutheil, B. Gado, H. C. E. Larsson, G. H. Lyon, J. D. Marcot, O. W. M. Rauhut, R. W. Sadleir, C. A. Sidor, D. D. Varricchio, G. P. Wilson & J. A. Wilson - 1998. - New information on the skull of the enigmatic theropod Spinosaurus, with remarks on its sizes and affinities. - Journal of Vertebrate Paleontology 25 (4): 888–896. - C. dal Sasso, S. Maganuco, E. Buffetaut & M. A. Mendez - 2005. - A reevaluation of Sigilmassasaurus brevicollis (Dinosauria) from the Cretaceous of Morocco. - Canadian Journal of Earth Sciences doi: 10.1139/cjes-2012-0129. - Bradley McFeeters, Michael J. Ryan, Sanja Hinic-Frlog & Claudia Schr�der-Adams - 2013. - Semiaquatic adaptations in a giant predatory dinosaur - Science vol. 345, no.6204 - Nizar Ibrahim, Paul C. Sereno, Cristiano Dal Sasso, Simone Maganuco, Matteo Fabbri, David M. Martill, Samir Zouhri, Nathan Myhrvold & Dawid A. Iurino - 2014. - A reappraisal of the morphology and systematic position of the theropod dinosaur Sigilmassasaurus from the ‘middle’ Cretaceous of Morocco. - PeerJ 3: e1323. - S. W. Evers, O. W. M. Rauhut, A. C. Milner, B. McFeeters & R. Allain - 2015. – Sigilmassasaurus is Spinosaurus: a reappraisal of African spinosaurines. – Cretaceous Research. 114: 104520. – R. S. H. Symth, N. Ibrahim & D. M. Martilla – 2020.
