Sigilmassasaurus
Name:
Sigilmassasaurus
(Sijilmassa lizard).
Phonetic: Se-jil-mas-sa-sor-us.
Named By: Dale Russel - 1996.
Synonyms: Spinosaurus maroccanus?
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Spinosauridae.
Species: S. brevicollis
(type).
Diet: Carnivore/Piscivore.
Size: Uncertain due to lack of remains.
Known locations: Morocco - Kem Kem Formation.
Time period: Cenomanian of the Cretaceous.
Fossil representation: Cervical (neck) vertebrae.
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 Muséum National d’Histoire
Naturelle, Paris, Série 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
Schröder-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.
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