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'''''Cristatusaurus''''' (meaning "crested lizard") is a [[genus]] of [[spinosaurid]] [[theropod]] [[dinosaur]] which lived during the Early [[Cretaceous]] Period of what is now [[West Africa]].
'''''Cristatusaurus''''' (meaning "crested lizard") is a [[genus]] of [[spinosaurid]] [[theropod]] [[dinosaur]] which lived during the Early [[Cretaceous]] Period of what is now [[West Africa]]. There is some debate over the identity of this creature, in that some argue that it is probably the same dinosaur as ''[[Suchomimus]],'' which has also been found in Niger, in the same sediment layers. In that case the name ''Cristatusaurus'' would have [[Scientific priority|priority]]. Others have concluded, however, that ''Cristatusaurus'' is a ''[[nomen dubium]]'', considering it indistinguishable from both ''Suchomimus'' and ''Baryonyx''.


== Discovery and naming ==
== Discovery and naming ==
[[File:Cristatusaurus claw.jpg|thumb|left|Claw fossil, [[Muséum national d'Histoire naturelle]], Paris]]
[[File:Cristatusaurus claw.jpg|thumb|left|Claw fossil, [[Muséum national d'Histoire naturelle]], Paris]]


Its [[Fossil|fossils]] were discovered in 1973 by French [[paleontologist]] [[Philippe Taquet]] at Gadoufaoua, a locality within the [[Elrhaz Formation]] in [[Niger]]. The [[holotype]], MNHN GDF 366, was found in the [[Tegema Beds]] dating from late [[Aptian]]. The material consists of two [[disarticulated]] [[praemaxilla|premaxilla]]e, a partial right [[maxilla]], and a lower jaw fragment. Several [[paratype]]s have been assigned: MNHN GDF 365, a snout of two articulated premaxillae; as well as MNHN GDF 357, 358, 359 and 361, four dorsal [[Vertebra|vertebrae]]. These fossils share a similarity to those of ''[[Baryonyx]]'' and ''[[Suchomimus]]''.<ref name="TaquetRussell" />
Its [[Fossil|fossils]] were discovered in 1973 by French [[paleontologist]] [[Philippe Taquet]] at Gadoufaoua, a locality within the [[Elrhaz Formation]] in [[Niger]]. The [[holotype]], MNHN GDF 366, was found in the [[Tegema Beds]] dating from late [[Aptian]]. The material consists of two [[disarticulated]] [[praemaxilla|premaxilla]]e, a partial right [[maxilla]], and a lower jaw fragment. Several [[paratype]]s have been assigned: MNHN GDF 365, a snout of two articulated premaxillae; as well as MNHN GDF 357, 358, 359 and 361, four dorsal [[Vertebra|vertebrae]].<ref name="TaquetRussell" />


In [[1998 in paleontology|1998]] the [[type species]], ''Cristatusaurus lapparenti'', was formally described by Taquet and American [[geologist]] [[Dale Russell]]. The generic name, originating from the [[Latin]] ''crista'' (for "crest"), refers to a [[sagittal crest]] on the snout. The [[specific name (zoology)|specific name]] honors the late French paleontologist [[Albert-Félix de Lapparent]].<ref name="TaquetRussell">Taquet, P. and Russell, D.A. (1998). "New data on spinosaurid dinosaurs from the Early Cretaceous of the Sahara". ''Comptes Rendus de l'Académie des Sciences à Paris, Sciences de la Terre et des Planètes'' 327: 347-353</ref>
In [[1998 in paleontology|1998]] the [[type species]], ''Cristatusaurus lapparenti'', was formally described by Taquet and American [[geologist]] [[Dale Russell]]. The generic name, originating from the [[Latin]] ''crista'' (for "crest"), refers to a [[sagittal crest]] on the snout. The [[specific name (zoology)|specific name]] honors the late French paleontologist [[Albert-Félix de Lapparent]]. In the same paper, several skull and vertebral fossils were referred to a new species of ''[[Spinosaurus]]'' called ''S. maroccanus,'' which was described and compared to ''Cristatusaurus''.<ref name="TaquetRussell">Taquet, P. and Russell, D.A. (1998). "New data on spinosaurid dinosaurs from the Early Cretaceous of the Sahara". ''Comptes Rendus de l'Académie des Sciences à Paris, Sciences de la Terre et des Planètes'' 327: 347-353</ref> Another spinosaurid from the Elrhaz, ''[[Suchomimus]]'', was named less than a month after ''Cristatusaurus''; the material (a partial skeleton) was described by [[Paul Sereno]] and colleagues.''<ref name="serenoetal98">{{cite journal|last1=Sereno|first1=P.C.|last2=Beck|first2=A.L.|last3=Dutheuil|first3=D.B.|last4=Gado|first4=B.|last5=Larsson|first5=H.C.|last6=Lyon|first6=G.H.|last7=Marcot|first7=J.D.|last8=Rauhut|first8=O.W.M.|last9=Sadleir|first9=R.W.|year=1998|title=A long-snouted predatory dinosaur from Africa and the evolution of spinosaurids|url=|journal=Science|volume=282|issue=5392|pages=1298–1302|bibcode=1998Sci...282.1298S|doi=10.1126/science.282.5392.1298|pmid=9812890|last10=Sidor|first10=C.A.|last11=Varricchio|first11=D.J.|last12=Wilson|first12=G.P.|last13=Wilson|first13=J.A.}}</ref>''


== Description and classification ==
== Description and classification ==
⚫
[[File:Cristatusaurus.jpg|thumb|Alternate views of the jaw pieces]]


''Cristatusaurus'' has closely spaced teeth and a short premaxilla that gets deeper towards the rear.<ref name="TaquetRussell" /> It has a dorsal sagittal crest on its snout, a feature also present in ''[[Baryonyx]], [[Suchomimus]]'', and very prominent in ''Angaturama''.<ref name=":0">{{Cite journal|last=Sales|first=Marcos A. F.|last2=Schultz|first2=Cesar L.|date=2017-11-06|title=Spinosaur taxonomy and evolution of craniodental features: Evidence from Brazil|journal=PLOS ONE|language=en|volume=12|issue=11|pages=e0187070|doi=10.1371/journal.pone.0187070|issn=1932-6203|pmc=5673194|pmid=29107966|bibcode=2017PLoSO..1287070S}}</ref> The type material is probably from a juvenile individual, based on the lack of fused [[Skull suture|sutures]] on the premaxillae. Taquet and Russel diagnosed ''Cristatusaurus'' as separate from ''Baryonyx'' on the basis of a more reduced snout, and from ''Irritator'' and ''Angaturama'' due to the presence of serrations. <ref name="TaquetRussell" />
''Cristatusaurus'' has a short premaxilla that gets deeper towards the rear.<ref name="TaquetRussell" /> There is a dorsal sagittal crest on its [[Rostrum (anatomy)|rostrum]] (snout), a feature also seen in ''[[Baryonyx]], [[Suchomimus]]'', and to a greater extent in ''Angaturama'' (a possible synonym of ''[[Irritator]]'').<ref name=":0">{{Cite journal|last=Sales|first=Marcos A. F.|last2=Schultz|first2=Cesar L.|date=2017-11-06|title=Spinosaur taxonomy and evolution of craniodental features: Evidence from Brazil|journal=PLOS ONE|language=en|volume=12|issue=11|pages=e0187070|doi=10.1371/journal.pone.0187070|issn=1932-6203|pmc=5673194|pmid=29107966|bibcode=2017PLoSO..1287070S}}</ref> There are seven [[Dental alveolus|alveoli]] (tooth sockets) on either side of the premaxillae, as seen The type material is probably from a juvenile individual, based on the lack of fused [[Skull suture|sutures]] on the premaxillae.<ref name="TaquetRussell" /> ''Spinosaurus maroccanus'' is now considered by most scientists either a [[dubious name]],''<ref name="dalsassoetal05">{{cite journal|last=dal Sasso|first=C.|author2=Maganuco, S.|author3=Buffetaut, E.|author4=Mendez, M.A.|year=2005|title=New information on the skull of the enigmatic theropod ''Spinosaurus'', with remarks on its sizes and affinities|url=http://www.bioone.org/doi/10.1671/0272-4634%282005%29025%5B0888%3ANIOTSO%5D2.0.CO%3B2|format=Submitted manuscript|journal=Journal of Vertebrate Paleontology|volume=25|issue=4|pages=888–896|doi=10.1671/0272-4634(2005)025[0888:NIOTSO]2.0.CO;2|issn=0272-4634}}</ref><ref name="BufOua02">{{cite journal|author1=Buffetaut, E.|author2=Ouaja, M.|last-author-amp=yes|year=2002|title=A new specimen of ''Spinosaurus'' (Dinosauria, Theropoda) from the Lower Cretaceous of Tunisia, with remarks on the evolutionary history of the Spinosauridae|url=http://documents.irevues.inist.fr/bitstream/handle/2042/216/04.pdf|journal=Bulletin de la Société Géologique de France|volume=173|issue=5|pages=415–421|doi=10.2113/173.5.415}}</ref><ref name="Rauhut03">{{cite journal|author=Rauhut, O.W.M.|year=2003|title=The interrelationships and evolution of basal theropod dinosaurs|journal=Special Papers in Palaeontology|volume=69|pages=1–213|isbn=978-0-901702-79-1}}</ref>'' or a synonym of ''S. aegyptiacus.<ref name="serenoetal98" />''


British paleontologists [[Alan charig|Alan Charig]] and [[Angela Milner]] while describing ''Baryonyx walkeri'' in [[1997 in paleontology|1997]], did not observe any aspects distinguishing it from the specimens later attributed to ''Cristatusaurus lapparenti'', concluding that they represented an indeterminate ''Baryonyx'' species.<ref name="charigmilner1997">{{Cite journal|last=Charig|first=A. J.|last2=Milner|first2=A. C.|year=1997|title=''Baryonyx walkeri'', a fish-eating dinosaur from the Wealden of Surrey|url=http://biostor.org/reference/110558|journal=Bulletin of the Natural History Museum of London|series=|volume=53|pages=11–70}}</ref> When Russel used the bones to erect a new genus in 1998, he based ''Cristatusaurus''<nowiki/>'s separateness from ''Baryonyx'' on the former's "brevirostrine condition of premaxilla".<ref name="TaquetRussell" /> The meaning of this diagnosis has been considered obscure by subsequent authors, who describe the specimens as nearly identical to those of ''Baryonyx'' and ''Suchomimus.''<ref name=":1">{{Cite journal|last=Bertin|first=Tor|date=2010-12-08|title=A catalogue of material and review of the Spinosauridae|url=https://www.researchgate.net/publication/235679976_A_catalogue_of_material_and_review_of_the_Spinosauridae|journal=PalArch's Journal of Vertebrate Palaeontology|volume=7}}</ref> Some, like [[Paul Sereno]], propose that ''Cristatusaurus'' is a [[Nomen dubium|''nomen dubium'']];''<ref name="serenoetal98" />'' while others, such as [[Eric Buffetaut]] and Mohamed Ouaja, support it as a [[junior synonym]] of ''Baryonyx.<ref name="BufOua02" />'' [[Hans-Dieter Sues]] and colleagues regard both ''Cristatusaurus'' and ''Suchomimus'' as junior synonyms of ''Baryonyx,'' asserting that there is no fossil evidence indicating that more than one spinosaur taxon lived in the Elrhaz Formation.<ref>{{Cite journal|last=Sues|first=Hans-Dieter|last2=Frey|first2=Eberhard|last3=Martill|first3=David|last4=Scott|first4=Diane|date=2002-09-19|title=Irritator challengeri, a Spinosaurid (Dinosauria: Theropoda) from the Lower Cretaceous of Brazil|url=https://www.researchgate.net/publication/254314432_Irritator_challengeri_a_Spinosaurid_Dinosauria_Theropoda_from_the_Lower_Cretaceous_of_Brazil|journal=Journal of Vertebrate Paleontology - J VERTEBRATE PALEONTOL|volume=22|pages=535–547|doi=10.1671/0272-4634(2002)022[0535:ICASDT]2.0.CO;2}}</ref> Most researchers have retained ''Suchomimus'' and ''Baryonyx'' as distinct genera.<ref name="Mateus 2011">{{cite journal|last1=Mateus|first1=O.|last2=Araújo|first2=R.|last3=Natário|first3=C.|last4=Castanhinha|first4=R.|year=2011|title=A new specimen of the theropod dinosaur ''Baryonyx'' from the early Cretaceous of Portugal and taxonomic validity of ''Suchosaurus''|url=http://docentes.fct.unl.pt/sites/default/files/omateus/files/mateus_et_al_2011_a_new_specimen_of_the_theropod_dinosaur_baryonyx_from_the_early_cretaceous_of_portugal_and_taxonomic_validity_of_suchosaurus.pdf|journal=Zootaxa|series=2827|pages=54–68}}</ref><ref name="AXRK12">{{cite journal|last1=Allain|first1=R.|last2=Xaisanavong|first2=T.|last3=Richir|first3=P.|last4=Khentavong|first4=B.|year=2012|title=The first definitive Asian spinosaurid (Dinosauria: Theropoda) from the early cretaceous of Laos|journal=Naturwissenschaften|volume=99|issue=5|pages=369–377|bibcode=2012NW.....99..369A|doi=10.1007/s00114-012-0911-7|pmc=|pmid=22528021}}</ref><ref name="bensonetal2010">{{cite journal|last1=Benson|first1=R. B. J.|last2=Carrano|first2=M. T.|last3=Brusatte|first3=S. L.|year=2009|title=A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic|url=https://repository.si.edu/bitstream/handle/10088/8609/paleo_Benson_10.pdf;https://repository.si.edu/bitstream/handle/10088/8609/paleo_Benson_10_supplemental_data.pdf|format=Submitted manuscript|journal=Naturwissenschaften|volume=97|issue=1|pages=71–78|bibcode=2010NW.....97...71B|doi=10.1007/s00114-009-0614-x|pmid=19826771}}</ref><ref name=":2">{{Cite journal|last=HONE|first=David William Elliott|last2=HOLTZ|first2=Thomas Richard|date=2017|title=A Century of Spinosaurs - A Review and Revision of the Spinosauridae with Comments on Their Ecology|url=https://onlinelibrary.wiley.com/doi/epdf/10.1111/1755-6724.13328|journal=Acta Geologica Sinica - English Edition|language=en|volume=91|issue=3|pages=1120–1132|doi=10.1111/1755-6724.13328|issn=1000-9515|via=}}</ref> and some also retain ''Cristatusaurus'' as a valid taxon.<ref name=":3">{{Cite book|url=https://books.google.com/?id=vtZFDb_iw40C&pg=PA98&dq=cristatusaurus#v=onepage&q=cristatusaurus&f=false|title=The Dinosauria|last=Weishampel|first=David B.|last2=Dodson|first2=Peter|last3=Osmólska|first3=Halszka|date=2004-12-06|publisher=University of California Press|isbn=9780520941434|language=en}}</ref><ref name="DescOxalaia">{{cite journal|last=Kellner|first=Alexander W. A.|last2=Azevedo|first2=Sergio A. K.|last3=Machado|first3=Elaine B.|last4=Carvalho|first4=Luciana B.|last5=Henriques|first5=Deise D. R.|year=2011|title=A new dinosaur (Theropoda, Spinosauridae) from the Cretaceous (Cenomanian) Alcântara Formation, Cajual Island, Brazil|url=http://www.scielo.br/pdf/aabc/v83n1/v83n1a06.pdf|journal=Anais da Academia Brasileira de Ciências|volume=83|issue=1|pages=99–108|doi=10.1590/S0001-37652011000100006|issn=0001-3765}}</ref> Given that it was named first, ''Cristatusaurus lapparenti'' has [[Principle of Priority|priority]] over ''Suchomimus tenerensis'' in the case that they become synonymized.<ref name=":3" /> In light of the disagreement between various paleontologists on the subject, and the fragmentary nature of the type elements, some authors propose that the best assignment for ''Cristatusaurus'' is baryonychinae indet.<ref name=":1" /><ref>{{Cite journal|last=Carrano|first=Matthew T.|last2=Benson|first2=Roger B. J.|last3=Sampson|first3=Scott D.|date=2012-05-17|title=The phylogeny of Tetanurae (Dinosauria: Theropoda)|url=https://www.tandfonline.com/doi/abs/10.1080/14772019.2011.630927|journal=Journal of Systematic Palaeontology|language=en|volume=10|issue=2|pages=211–300|doi=10.1080/14772019.2011.630927|issn=1477-2019}}</ref>
⚫
[[File:Cristatusaurus.jpg|thumb|Alternate views of the jaw fragments]]


Although the genus and species placement of ''Cristatusaurus lapparenti'' is disputed, the fossils certainly belong to a member of the baryonychinae [[subfamily]], because of the relatively larger first premaxillary teeth than in spinosaurines; and the presence of fine serrations, in contrast to spinosaurines lacking them entirely.<ref name=":0" /><ref name=":2" />
There is some debate over the identity of this creature, in that some argue that it is probably the same dinosaur as ''Suchomimus,'' which has also been found in Niger, in the same sediment layers. In that case the name ''Cristatusaurus'' would have [[Scientific priority|priority]]. Others have concluded, however, that ''Cristatusaurus'' is a ''[[nomen dubium]]'', considering it indistinguishable from both ''Suchomimus'' and ''Baryonyx''.<ref name="Rauhut">Rauhut, O.W.M. (2003). "The interrelationships and evolution of basal theropod dinosaurs". ''Special Papers in Palaeontology'' 69: 1-213.</ref> Given that it was named first, ''Cristatusaurus lapparenti'' has [[Principle of Priority|priority]] over ''Suchomimus tenerensis'' in the case that they become [[Synonym (taxonomy)|synonyms]].<ref>{{Cite book|url=https://books.google.com/?id=vtZFDb_iw40C&pg=PA98&dq=cristatusaurus#v=onepage&q=cristatusaurus&f=false|title=The Dinosauria|last=Weishampel|first=David B.|last2=Dodson|first2=Peter|last3=Osmólska|first3=Halszka|date=2004-12-06|publisher=University of California Press|isbn=9780520941434|language=en}}</ref>

[[File:Erlhaz_Formation.jpg|thumb|Restoration of ''Cristatusaurus'' in the [[Erlhaz Formation]] with ''[[Nigersaurus]]'']]


The following [[cladogram]] is from a phylogenetic analysis by Marcos Sales and Cesar Shultz in 2017:<ref name=":0" />
The following [[cladogram]] is from a phylogenetic analysis by Marcos Sales and Cesar Shultz in 2017:<ref name=":0" />
Line 40: Line 43:


== Paleoecology ==
== Paleoecology ==
The [[Early Cretaceous]] Elrhaz Formation, which has been interpreted as a habitat of vast [[Floodplain|floodplains]],<ref name="serenoetal2007">{{Cite journal|last1=Sereno|first1=P. C.|last2=Wilson|first2=J. A.|last3=Witmer|first3=L. M.|last4=Whitlock|first4=J. A.|last5=Maga|first5=A.|last6=Ide|first6=O.|last7=Rowe|first7=T. A.|year=2007|title=Structural extremes in a Cretaceous dinosaur|journal=PLoS ONE|volume=2|issue=11|pages=e1230|bibcode=2007PLoSO...2.1230S|doi=10.1371/journal.pone.0001230|pmc=2077925|pmid=18030355}}. {{open access}}</ref> was home to a large amount of fauna including dinosaurs, [[Pterosaur|pterosaurs]], [[chelonians]], fish, [[hybodont]] sharks, and freshwater bivalves.''<ref name="ecology">{{Cite journal|last1=Sereno|first1=P. C.|last2=Brusatte|first2=S. L.|year=2008|title=Basal abelisaurid and carcharodontosaurid theropods from the Lower Cretaceous Elrhaz Formation of Niger|journal=Acta Palaeontologica Polonica|volume=53|issue=1|pages=15–46|doi=10.4202/app.2008.0102|pmc=|pmid=}}</ref>'' Besides ''Cristatusaurus'' and ''Suchomimus,'' theropods such as ''[[Kryptops]]'', ''[[Eocarcharia]]'', and an unknown [[Noasauridae|noasaurid]] have been found. Herbivorous dinosaurs in the region included [[Iguanodontia|iguanodontians]] like ''[[Ouranosaurus]]'', ''[[Elrhazosaurus]], [[Lurdusaurus]],'' and the [[Sauropoda|sauropod]] <u>''[[Nigersaurus]]''</u>. [[Crocodylomorpha|Crocodylomorphs]] were abundant; represented by ''[[Sarcosuchus]]'', ''[[Anatosuchus]]'', ''[[Araripesuchus]]'', and ''[[Stolokrosuchus]].<ref name="ecology" />''
The [[Early Cretaceous]] Elrhaz Formation is dated to the late [[Aptian]] to early [[Albian]] [[Stage (geology)|stages]] (112 million years ago).<ref name="serenoetal2007" /><ref name="sereno_2001">{{cite journal|last=Sereno|first=Paul C.|author2=Larson, Hans C. E.|author3=Sidor, Christian A.|author4=Gado, Boubé|year=2001|title=The Giant Crocodyliform Sarcosuchus from the Cretaceous of Africa|journal=Science|volume=294|issue=5546|pages=1516–9|bibcode=2001Sci...294.1516S|doi=10.1126/science.1066521|pmid=11679634}}</ref> It has been interpreted as a tropical inland habitat of vast freshwater [[Floodplain|floodplains]],<ref name="serenoetal2007">{{Cite journal|last1=Sereno|first1=P. C.|last2=Wilson|first2=J. A.|last3=Witmer|first3=L. M.|last4=Whitlock|first4=J. A.|last5=Maga|first5=A.|last6=Ide|first6=O.|last7=Rowe|first7=T. A.|year=2007|title=Structural extremes in a Cretaceous dinosaur|journal=PLoS ONE|volume=2|issue=11|pages=e1230|bibcode=2007PLoSO...2.1230S|doi=10.1371/journal.pone.0001230|pmc=2077925|pmid=18030355}}. {{open access}}</ref> that was home to a large amount of fauna including dinosaurs, [[Pterosaur|pterosaurs]], [[chelonians]], fish, [[hybodont]] sharks, and freshwater bivalves.<ref name="sereno_2001" />''<ref name="ecology">{{Cite journal|last1=Sereno|first1=P. C.|last2=Brusatte|first2=S. L.|year=2008|title=Basal abelisaurid and carcharodontosaurid theropods from the Lower Cretaceous Elrhaz Formation of Niger|journal=Acta Palaeontologica Polonica|volume=53|issue=1|pages=15–46|doi=10.4202/app.2008.0102|pmc=|pmid=}}</ref>'' Besides ''Cristatusaurus'' and ''Suchomimus,'' theropods such as the [[Abelisauridae|abelisaurid]] ''[[Kryptops]]'', the [[Carcharodontosauridae|carcharodontosaurid]] ''[[Eocarcharia]]'', and an unknown [[Noasauridae|noasaurid]] have been found. Herbivorous dinosaurs in the region included [[Iguanodontia|iguanodontians]] like ''[[Ouranosaurus]]'', ''[[Elrhazosaurus]], [[Lurdusaurus]],'' and two [[Sauropoda|sauropods]]: ''[[Nigersaurus]]'' and an unnamed [[titanosaur]]. [[Crocodylomorpha|Crocodylomorphs]] were abundant; represented by ''[[Sarcosuchus]]'', ''[[Anatosuchus]]'', ''[[Araripesuchus]]'', and ''[[Stolokrosuchus]].<ref name="ecology" />''


==References==
==References==

Revision as of 04:05, 31 August 2018

Cristatusaurus
Temporal range: Early Cretaceous
Holotype (MNHN GDF 366), consisting of jaw fossils, Muséum national d'Histoire naturelle, Paris
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Spinosauridae
Genus: †Cristatusaurus
Species:
†C. lapparenti
Binomial name
†Cristatusaurus lapparenti
Taquet and Russell, 1998

Cristatusaurus (meaning "crested lizard") is a genus of spinosaurid theropod dinosaur which lived during the Early Cretaceous Period of what is now West Africa. There is some debate over the identity of this creature, in that some argue that it is probably the same dinosaur as Suchomimus, which has also been found in Niger, in the same sediment layers. In that case the name Cristatusaurus would have priority. Others have concluded, however, that Cristatusaurus is a nomen dubium, considering it indistinguishable from both Suchomimus and Baryonyx.

Discovery and naming

Claw fossil, Muséum national d'Histoire naturelle, Paris

Its fossils were discovered in 1973 by French paleontologist Philippe Taquet at Gadoufaoua, a locality within the Elrhaz Formation in Niger. The holotype, MNHN GDF 366, was found in the Tegema Beds dating from late Aptian. The material consists of two disarticulated premaxillae, a partial right maxilla, and a lower jaw fragment. Several paratypes have been assigned: MNHN GDF 365, a snout of two articulated premaxillae; as well as MNHN GDF 357, 358, 359 and 361, four dorsal vertebrae.[1]

In 1998 the type species, Cristatusaurus lapparenti, was formally described by Taquet and American geologist Dale Russell. The generic name, originating from the Latin crista (for "crest"), refers to a sagittal crest on the snout. The specific name honors the late French paleontologist Albert-Félix de Lapparent. In the same paper, several skull and vertebral fossils were referred to a new species of Spinosaurus called S. maroccanus, which was described and compared to Cristatusaurus.[1] Another spinosaurid from the Elrhaz, Suchomimus, was named less than a month after Cristatusaurus; the material (a partial skeleton) was described by Paul Sereno and colleagues.[2]

Description and classification

Alternate views of the jaw pieces

Cristatusaurus has a short premaxilla that gets deeper towards the rear.[1] There is a dorsal sagittal crest on its rostrum (snout), a feature also seen in Baryonyx, Suchomimus, and to a greater extent in Angaturama (a possible synonym of Irritator).[3] There are seven alveoli (tooth sockets) on either side of the premaxillae, as seen The type material is probably from a juvenile individual, based on the lack of fused sutures on the premaxillae.[1] Spinosaurus maroccanus is now considered by most scientists either a dubious name,[4][5][6] or a synonym of S. aegyptiacus.[2]

British paleontologists Alan Charig and Angela Milner while describing Baryonyx walkeri in 1997, did not observe any aspects distinguishing it from the specimens later attributed to Cristatusaurus lapparenti, concluding that they represented an indeterminate Baryonyx species.[7] When Russel used the bones to erect a new genus in 1998, he based Cristatusaurus's separateness from Baryonyx on the former's "brevirostrine condition of premaxilla".[1] The meaning of this diagnosis has been considered obscure by subsequent authors, who describe the specimens as nearly identical to those of Baryonyx and Suchomimus.[8] Some, like Paul Sereno, propose that Cristatusaurus is a nomen dubium;[2] while others, such as Eric Buffetaut and Mohamed Ouaja, support it as a junior synonym of Baryonyx.[5] Hans-Dieter Sues and colleagues regard both Cristatusaurus and Suchomimus as junior synonyms of Baryonyx, asserting that there is no fossil evidence indicating that more than one spinosaur taxon lived in the Elrhaz Formation.[9] Most researchers have retained Suchomimus and Baryonyx as distinct genera.[10][11][12][13] and some also retain Cristatusaurus as a valid taxon.[14][15] Given that it was named first, Cristatusaurus lapparenti has priority over Suchomimus tenerensis in the case that they become synonymized.[14] In light of the disagreement between various paleontologists on the subject, and the fragmentary nature of the type elements, some authors propose that the best assignment for Cristatusaurus is baryonychinae indet.[8][16]

Although the genus and species placement of Cristatusaurus lapparenti is disputed, the fossils certainly belong to a member of the baryonychinae subfamily, because of the relatively larger first premaxillary teeth than in spinosaurines; and the presence of fine serrations, in contrast to spinosaurines lacking them entirely.[3][13]

Restoration of Cristatusaurus in the Erlhaz Formation with Nigersaurus

The following cladogram is from a phylogenetic analysis by Marcos Sales and Cesar Shultz in 2017:[3]

Spinosauridae

Paleoecology

The Early Cretaceous Elrhaz Formation is dated to the late Aptian to early Albian stages (112 million years ago).[17][18] It has been interpreted as a tropical inland habitat of vast freshwater floodplains,[17] that was home to a large amount of fauna including dinosaurs, pterosaurs, chelonians, fish, hybodont sharks, and freshwater bivalves.[18][19] Besides Cristatusaurus and Suchomimus, theropods such as the abelisaurid Kryptops, the carcharodontosaurid Eocarcharia, and an unknown noasaurid have been found. Herbivorous dinosaurs in the region included iguanodontians like Ouranosaurus, Elrhazosaurus, Lurdusaurus, and two sauropods: Nigersaurus and an unnamed titanosaur. Crocodylomorphs were abundant; represented by Sarcosuchus, Anatosuchus, Araripesuchus, and Stolokrosuchus.[19]

References

  1. ^ a b c d e Taquet, P. and Russell, D.A. (1998). "New data on spinosaurid dinosaurs from the Early Cretaceous of the Sahara". Comptes Rendus de l'Académie des Sciences à Paris, Sciences de la Terre et des Planètes 327: 347-353
  2. ^ a b c Sereno, P.C.; Beck, A.L.; Dutheuil, D.B.; Gado, B.; Larsson, H.C.; Lyon, G.H.; Marcot, J.D.; Rauhut, O.W.M.; Sadleir, R.W.; Sidor, C.A.; Varricchio, D.J.; Wilson, G.P.; Wilson, J.A. (1998). "A long-snouted predatory dinosaur from Africa and the evolution of spinosaurids". Science. 282 (5392): 1298–1302. Bibcode:1998Sci...282.1298S. doi:10.1126/science.282.5392.1298. PMID 9812890.
  3. ^ a b c Sales, Marcos A. F.; Schultz, Cesar L. (2017-11-06). "Spinosaur taxonomy and evolution of craniodental features: Evidence from Brazil". PLOS ONE. 12 (11): e0187070. Bibcode:2017PLoSO..1287070S. doi:10.1371/journal.pone.0187070. ISSN 1932-6203. PMC 5673194. PMID 29107966.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  4. ^ dal Sasso, C.; Maganuco, S.; Buffetaut, E.; Mendez, M.A. (2005). "New information on the skull of the enigmatic theropod Spinosaurus, with remarks on its sizes and affinities" (Submitted manuscript). Journal of Vertebrate Paleontology. 25 (4): 888–896. doi:10.1671/0272-4634(2005)025[0888:NIOTSO]2.0.CO;2. ISSN 0272-4634.
  5. ^ a b Buffetaut, E.; Ouaja, M. (2002). "A new specimen of Spinosaurus (Dinosauria, Theropoda) from the Lower Cretaceous of Tunisia, with remarks on the evolutionary history of the Spinosauridae" (PDF). Bulletin de la Société Géologique de France. 173 (5): 415–421. doi:10.2113/173.5.415. {{cite journal}}: Unknown parameter |last-author-amp= ignored (|name-list-style= suggested) (help)
  6. ^ Rauhut, O.W.M. (2003). "The interrelationships and evolution of basal theropod dinosaurs". Special Papers in Palaeontology. 69: 1–213. ISBN 978-0-901702-79-1.
  7. ^ Charig, A. J.; Milner, A. C. (1997). "Baryonyx walkeri, a fish-eating dinosaur from the Wealden of Surrey". Bulletin of the Natural History Museum of London. 53: 11–70.
  8. ^ a b Bertin, Tor (2010-12-08). "A catalogue of material and review of the Spinosauridae". PalArch's Journal of Vertebrate Palaeontology. 7.
  9. ^ Sues, Hans-Dieter; Frey, Eberhard; Martill, David; Scott, Diane (2002-09-19). "Irritator challengeri, a Spinosaurid (Dinosauria: Theropoda) from the Lower Cretaceous of Brazil". Journal of Vertebrate Paleontology - J VERTEBRATE PALEONTOL. 22: 535–547. doi:10.1671/0272-4634(2002)022[0535:ICASDT]2.0.CO;2.
  10. ^ Mateus, O.; Araújo, R.; Natário, C.; Castanhinha, R. (2011). "A new specimen of the theropod dinosaur Baryonyx from the early Cretaceous of Portugal and taxonomic validity of Suchosaurus" (PDF). Zootaxa. 2827: 54–68.
  11. ^ Allain, R.; Xaisanavong, T.; Richir, P.; Khentavong, B. (2012). "The first definitive Asian spinosaurid (Dinosauria: Theropoda) from the early cretaceous of Laos". Naturwissenschaften. 99 (5): 369–377. Bibcode:2012NW.....99..369A. doi:10.1007/s00114-012-0911-7. PMID 22528021.
  12. ^ Benson, R. B. J.; Carrano, M. T.; Brusatte, S. L. (2009). "A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic" (Submitted manuscript). Naturwissenschaften. 97 (1): 71–78. Bibcode:2010NW.....97...71B. doi:10.1007/s00114-009-0614-x. PMID 19826771.
  13. ^ a b HONE, David William Elliott; HOLTZ, Thomas Richard (2017). "A Century of Spinosaurs - A Review and Revision of the Spinosauridae with Comments on Their Ecology". Acta Geologica Sinica - English Edition. 91 (3): 1120–1132. doi:10.1111/1755-6724.13328. ISSN 1000-9515.
  14. ^ a b Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (2004-12-06). The Dinosauria. University of California Press. ISBN 9780520941434.
  15. ^ Kellner, Alexander W. A.; Azevedo, Sergio A. K.; Machado, Elaine B.; Carvalho, Luciana B.; Henriques, Deise D. R. (2011). "A new dinosaur (Theropoda, Spinosauridae) from the Cretaceous (Cenomanian) Alcântara Formation, Cajual Island, Brazil" (PDF). Anais da Academia Brasileira de Ciências. 83 (1): 99–108. doi:10.1590/S0001-37652011000100006. ISSN 0001-3765.
  16. ^ Carrano, Matthew T.; Benson, Roger B. J.; Sampson, Scott D. (2012-05-17). "The phylogeny of Tetanurae (Dinosauria: Theropoda)". Journal of Systematic Palaeontology. 10 (2): 211–300. doi:10.1080/14772019.2011.630927. ISSN 1477-2019.
  17. ^ a b Sereno, P. C.; Wilson, J. A.; Witmer, L. M.; Whitlock, J. A.; Maga, A.; Ide, O.; Rowe, T. A. (2007). "Structural extremes in a Cretaceous dinosaur". PLoS ONE. 2 (11): e1230. Bibcode:2007PLoSO...2.1230S. doi:10.1371/journal.pone.0001230. PMC 2077925. PMID 18030355.{{cite journal}}: CS1 maint: unflagged free DOI (link). Open access icon
  18. ^ a b Sereno, Paul C.; Larson, Hans C. E.; Sidor, Christian A.; Gado, Boubé (2001). "The Giant Crocodyliform Sarcosuchus from the Cretaceous of Africa". Science. 294 (5546): 1516–9. Bibcode:2001Sci...294.1516S. doi:10.1126/science.1066521. PMID 11679634.
  19. ^ a b Sereno, P. C.; Brusatte, S. L. (2008). "Basal abelisaurid and carcharodontosaurid theropods from the Lower Cretaceous Elrhaz Formation of Niger". Acta Palaeontologica Polonica. 53 (1): 15–46. doi:10.4202/app.2008.0102.
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