View source for Hyposaurus

{{Short description|Extinct genus of reptiles}}
{{Automatic taxobox
| taxon = Hyposaurus
| fossil_range = [[Maastrichtian]]–[[Paleocene]]<br />~{{Fossil range|earliest=Campanian|67|60}}
| authority = [[Richard Owen|Owen]], 1849
| subdivision_ranks = [[Species]]
| subdivision = 
* {{extinct}}''H. derbianus'' {{small|[[Edward Drinker Cope|Cope]] 1886}}
* {{extinct}}''H. nopcsai'' {{small|Swinton 1930}}
* {{extinct}}''H. paucidens'' {{small|Arambourg 1952}}
* {{extinct}}''H. rogersii'' {{small|[[Richard Owen|Owen]] 1849}}
* {{extinct}}''H. wilsoni'' {{small|Swinton 1930}}
| type_species = '''''Hyposaurus rogersii'''''
| type_species_authority = [[Richard Owen|Owen]], 1849
}}

'''''Hyposaurus''''' is a [[genus]] of [[extinct]] marine [[Dyrosauridae|dyrosaurid]] [[crocodyliform]]. Fossils have been found in [[Paleocene]] aged rocks of the [[Iullemmeden Basin]] in [[West Africa]],<ref name=SJ07>{{Cite journal |last=Jouve |first=S. |title=Taxonomic revision of the dyrosaurid assemblage (Crocodyliformes: Mesoeucrocodylia) from the Paleocene of the Iullemmeden Basin, West Africa |journal=Journal of Paleontology |volume=81 |issue=1 |pages=163–175 |year=2007 |doi=10.1666/0022-3360(2007)81[163:TROTDA]2.0.CO;2|s2cid=86329623 }}</ref> [[Campanian]]–[[Maastrichtian]] ([[Late Cretaceous|Late]] [[Cretaceous]]) [[Shendi Formation]] of [[Sudan]]<ref name="SALIH">{{Cite journal |author1=Khalaf Allah O. Salih |author2=David C. Evans |author3=Robert Bussert |author4=Nicole Klein |author5=Mutwakil Nafi |author6=Johannes Müller |title=First record of ''Hyposaurus'' (Dyrosauridae, Crocodyliformes) from the Upper Cretaceous Shendi Formation of Sudan |journal=Journal of Vertebrate Paleontology |volume=36 |issue=1 |pages=e1115408 |year=2016 |doi=10.1080/02724634.2016.1115408 |s2cid=86299028 }}</ref> and [[Maastrichtian]] (Late Cretaceous) through [[Danian]] (Early [[Paleocene]]) strata in [[New Jersey]], [[Alabama]] and [[South Carolina]]. With an Indeterminate species from the [[Selandian|Mid]] to [[Thanetian|Late]] [[Paleocene|Palaeocene]] [[Teberemt Formation]] of [[Mali]].<ref>{{Cite web |title=PBDB Collection |url=https://paleobiodb.org/classic/displayCollResults?collection_no=83314 |access-date=2025-03-07 |website=paleobiodb.org}}</ref> Isolated [[teeth]] comparable to ''Hyposaurus'' have also been found in [[Thanetian]] (Late Paleocene) strata of [[Virginia]].<ref name=ELT25>{{Cite journal |author=Troxell, E.L. |title=''Hyposaurus'', a marine crocodilian |journal=American Journal of Science |series=Series 5 |volume=9 |pages=489–514 |year=1925 |issue=54 |doi=10.2475/ajs.s5-9.54.489 |bibcode=1925AmJS....9..489T |url=http://www.ajsonline.org/cgi/content/abstract/s5-9/54/489|url-access=subscription }}</ref><ref name=Dentonetal>Denton Jr., R. K., Dobie, J. L. and D. C. Parris, 1997. The Marine Crocodilian ''Hyposaurus'' in North America. from Ancient Marine Reptiles, editors J. M. Callaway and E. L. Nicholls, Academic Press.</ref> It was related to ''[[Dyrosaurus]]''. The priority of the [[species]] ''H. rogersii'' has been debated,<ref>Parris, D. C. 1986, Biostratigraphy of the fossil crocodile ''Hyposaurus'' Owen from New Jersey. Investigations of the New Jersey State Museum 4:1-16</ref><ref>Norell, M. A. and G. W. Storrs. 1989. Catalogue and review of the type fossil crocodilians in the Yale Peabody Museum. Postilla 203:1-28</ref> however there is no sound basis for the recognition of more than one species from North America. The other [[North American]] species (i.e. ''H. fraterculus'', ''H. ferox'' and ''H. natator'') are therefore considered ''[[Nomen vanum|nomina vana]]'' (i.e. empty names).<ref name=Dentonetal />

== Introduction ==
''Hyposaurus'' is an extinct [[reptile]] whose fossils are found in [[Sea|marine]] sediments from the Maastrichtian (latest Cretaceous age) to the Danian (earliest Paleocene age).<ref name=Dentonetal />  It is a mesosuchian crocodyliform in the family Dyrosauridae.<ref name= Dentonetal /> It is closely related to dyrosaurs and congosaurs (Schwarz-Wings). The earliest fossils were found in [[North America]], and they were later discovered in [[Africa]] and [[South America]].<ref name= Dentonetal /> The [[genus]] is believed to have originated in Africa.<ref name=HAST11>{{Cite journal |author1=Alexander K. Hastings |author2=Jonathan I. Bloch |author3=Carlos A. Jaramillo |title = A New Longirostrine Dyrosaurid (Crocodylomorpha, Mesoeucrocodylia) From the Paleocene of North-Eastern Colombia: Biogeographic and Behavioural Implications for New-World Dyrosauridae |journal= Palaeontology |volume=54 |issue=5 |pages=1095–1116 |year=2011|doi=10.1111/j.1475-4983.2011.01092.x |doi-access= }}</ref><ref name="SALIH"/> ''Hyposaurus'' lived in a shallow, near shore marine environment and has many aquatic adaptations <ref name= Dentonetal /> In 2009, the disorganized phylogeny of crocodyliforms was treated and reliable diagnostic traits established, but remaining questions are unanswered.<ref name=SCH09>{{Cite journal |author1=Daniela Schwarz |author2=Eberhard Frey |author3=Thomas Martin |title = Reconstruction of the Bracing System of the Trunk and Tail in Hyposaurine Dyrosaurids (Crocodylomorpha; Mesoeucrocodylia) |journal=[[Journal of Vertebrate Paleontology]] |volume=29 |issue=2 |pages=453–472 |year=2009|doi=10.1671/039.029.0228 |s2cid=84850546 }}</ref>

== Early discoveries ==
Owen first recognized the genus in 1849.<ref name=OWEN>{{Cite journal |first=Richard |last=[[Richard Owen|Owen]] |title=Notes on the remains of a fossil reptile discovered by professor Henry Rogers of Pennsylvania, United States, in greensand formations of New Jersey |journal=[[Proceedings of the Geological Society of London]] |volume=5 |pages=380–383 |year=1849}}</ref> This first fossil was two amphicoelous vertebrae, vertebrae with two concave sides of the centrum, discovered by Professor Henry Roger. It was found in the greensand beds in New Jersey.<ref name=OWEN /> The different greensand beds of New Jersey represent a complete record from the Cretaceous to the Paleocene. They are estimated to cover {{convert|10000|sqmi|km2}} of sea floor but are limited on land to coastal environments.<ref name=CLARK>{{cite journal |last1=Clark |first1=William Bullock |title=Origin and Classification of the Greensands of New Jersey |journal=The Journal of Geology |date=1894 |volume=2 |issue=2 |pages=161–177 |doi=10.1086/606910 |jstor=30054487|bibcode=1894JG......2..161C |s2cid=129701440 }}</ref> In honor of professor Roger, Owen named this new fossil ''Hyposaurus rogersii''.<ref name=OWEN /> The genus name is meant to describe the unique "hypapophyseal keel extended on the ventral surface of the centrum".<ref name=Dentonetal /> This is an extension of the vertebrae centrum which point down towards the belly, similar to a boat [[keel]].
The second fossil find was by Cope in 1886.<ref name=COPE>{{Cite journal |first=E. D. |last=[[Edward Drinker Cope|Cope]] |title=A Contribution to the Vertebrate Paleontology of Brazil. |url=https://archive.org/details/jstor-982910 |journal=[[Proceedings of the American Philosophical Society]] |year=1886 |volume=23 |issue=121 |pages=1–21 |jstor=982910 }}</ref> This fossil was found in Brazil and comprises a left molar, [[quadratojugal bone]], a lower jaw, many vertebrae from the middle to posterior parts of the column, a [[humerus]], a [[coracoid]] bone, teeth, and several other bones.<ref name=COPE /> It had been hypothesized ''Hyposaurus'' was related to ''Teleosaurus'' and this fossil evidence allowed Cope to propose ''Hyposaurus'' was part of the family [[Teleosauridae]].<ref name=Dentonetal /><ref name=COPE /> The differences between ''Hyposaurus'' and ''Teleosaurus'' are described as "the robust size and vertical direction" of the teeth of ''Hyposaurus'', as well as ''Hyposaurus'' had hypapophyses{{clarify|date=March 2020}} on more dorsal vertebrae than ''Teleosaurus'', which only has these on the first and second dorsal vertebrae.<ref name=COPE /> Cope remarks the characteristics of ''H. rogersii'' and his new specimen are very similar, but the articular faces of the centrum are less concave than ''H. rogersii''.<ref name=COPE /> The species was named ''Hyposaurus derbianus'' after professor [[Orville Derby]], the director of the department of Geology at the [[National Museum of Brazil]].<ref name=COPE />

== Description ==
In 2006, Schwarz and colleagues,<ref name=SCHWARZ/> described the postcranial skeletons of new specimens of ''Hyposaurus'', focusing mostly on the vertebrae. From partial skeletons a [[proatlas]], [[atlas]], [[Axis (anatomy)|axis]], a third to ninth [[cervical vertebrae]], and at least 16 dorsal, two sacral, and 45 caudal vertebrae have been reconstructed.<ref name=SCHWARZ /> The vertebrae are weakly amphicoelous, meaning both sides of the centrum are concave. The dorsal shield is made of two columns of paravertebral [[osteoderm]]s and two lateral columns of accessory osteoderms. At least 12 horizontal rows of these make up the shield.<ref name=SCHWARZ />

The three main differences between the axial skeletons of ''Hyposaurus'' and modern crocodylians are the tall neural spines, vertically oriented thoracic ribs and osteoderm which lack external keels.<ref name=SCH09 /> This indicates that they also have a different epiaxial musculature (muscles above the axial skeleton).<ref name=SCH09 /> Along with the specialized osteoderm morphology, ''Hyposaurus'' probably had a specialized trunk bracing system which suggests that individuals with low body mass could have only high walked or galloped.<ref name=SCH09 />

== Distribution ==
{{Location map+ | World
| AlternativeMap=Land shallow topo 2048.jpg
| relief  = 1
| width   = 500
| float   = right
| caption = Locations of ''Hyposaurus'' fossil discoveries<br>[[File:Orange ff8040 pog.svg|10px]] [[Thanetian]]/[[Clarkforkian]]<br>[[File:Orange pog.svg|10px]] [[Paleocene|Early Paleocene]]<br>[[File:Lightgreen pog.svg|10px]] [[Maastrichtian]]<br>[[File:Green pog.svg|10px]] [[Campanian]]
| places  =
<!--(Early) Paleocene-->
  {{Location map~ | World
  | lat_deg = 39.8
  | lon_deg = -75.1
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  {{Location map~ | World
  | lat_deg = 32.1
  | lon_deg = -87.3
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  {{Location map~ | World
  | lat_deg = -7.9<!--Brazil-->
  | lon_deg = -34.9
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<!--Late Paleocene-->
  {{Location map~ | World
  | lat_deg = 38.3
  | lon_deg = -77.3
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  {{Location map~ | World
  | lat_deg = 33.4
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{{Location map~ | World
  | lat_deg = 17.4
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<!--Campanian-->
  {{Location map~ | World
  | lat_deg = 16.7 <!--Sudan-->
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  {{Location map~ | World
  | lat_deg = 39.5
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<!--Maastrichtian-->
  {{Location map~ | World
  | lat_deg = 39.7
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}}
Fossils of ''Hyposaurus'' have been found in North and South America and Africa.<ref name=COPE/><ref name=OWEN/><ref name=Dentonetal/><ref name="SALIH"/> There is evidence supporting presence of the genus ''Hyposaurus'' in Africa where the [[Dryosauridae]] originated.<ref name="SALIH"/><ref name=HASTINGS>{{Cite journal |author1=Alexander K. Hastings |author2=Jonathan I. Bloch |author3=Edwin A. Cadena |author4=Carlos A. Jaramillo |title= A new small short-snouted dyrosaurid (Crocodylomorpha, Mesoeucrocodylia) from the Paleocene of northeastern Colombia. |journal=Journal of Vertebrate Paleontology |volume=30 |issue=1 |pages=139–162 |year=2010|doi=10.1080/02724630903409204 |s2cid=84705605 |url=https://repository.urosario.edu.co/handle/10336/27642 |doi-access=free }}</ref> Dispersal into the New World is hypothesized to have taken place during the Late Cretaceous or Early Paleocene.<ref name=HASTINGS /> Hastings proposed three independent dispersal events of the dyrosaurid clade.<ref name=HAST11 /> These findings show a clear Atlantic focus in fossil distribution. ''Hyposaurus'' is believed to have been the only amphicoelous crocodylian in North America.<ref name=ELT25 /> It lasted long enough to live alongside the modern procoelous crocodylians which most other amphicoelous crocodylians did not.<ref name=ELT25 />

{| class="wikitable sortable"
! Age !! Formation !! Location !! Refs
|-
| style="background-color: {{period color|thanetian}};" | [[Clarkforkian]] || [[Williamsburg Formation]] || [[South Carolina]] || align=center | <ref>[http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=36596&max_interval=Paleocene&country=United%20States&state=South%20Carolina&is_real_user=1&basic=yes&type=view&match_subgenera=1 Fossilworks]{{dead link|date=November 2024|bot=medic}}{{cbignore|bot=medic}}</ref>
|-
| style="background-color: {{period color|thanetian}};" | [[Thanetian]] || [[Aquia Formation]] || [[Virginia]] || align=center | <ref>[http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=36596&max_interval=Paleocene&country=United%20States&state=Virginia&is_real_user=1&basic=yes&type=view&match_subgenera=1 Fossilworks]{{dead link|date=November 2024|bot=medic}}{{cbignore|bot=medic}}</ref>
|-
| style="background-color: {{period color|thanetian}};" | [[Thanetian]] || [[Teberemt Formation]] || [[Mali]] || align=center | <ref>{{Cite web |title=PBDB Collection |url=https://paleobiodb.org/classic/displayCollResults?collection_no=83314 |access-date=2025-03-07 |website=paleobiodb.org}}</ref>
|-
| style="background-color: {{period color|danian}};" | [[Danian]] || [[Clayton Formation]] || [[Alabama]] || align=center | <ref>[https://web.archive.org/web/20250119212044/http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=36596&max_interval=Paleocene&country=United%20States&state=Alabama&is_real_user=1&basic=yes&type=view&match_subgenera=1 Fossilworks]</ref>
|-
| style="background-color: {{period color|danian}};" | [[Danian]] || [[Hornerstown Formation]] || [[New Jersey]] || align=center | <ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=26820 Fossilworks]</ref>
|-
| style="background-color: {{period color|danian}};" | [[Danian]] || [[Maria Farinha Formation]] || [[Brazil]] || align=center | <ref>[http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=36596&max_interval=Paleocene&country=Brazil&is_real_user=1&basic=yes&type=view&match_subgenera=1 Fossilworks]{{dead link|date=November 2024|bot=medic}}{{cbignore|bot=medic}}</ref>
|-
| style="background-color: {{period color|paleocene}};" | [[Paleocene]] || [[Teberemt Formation]] || [[Mali]] || align=center | <ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=83314 Fossilworks]</ref>
|-
| style="background-color: {{period color|paleocene}};" | [[Paleocene]] || [[Dange Formation]] || [[Nigeria]] || align=center | <ref>[https://web.archive.org/web/20241126213401/http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=36596&max_interval=Paleocene&country=Nigeria&is_real_user=1&basic=yes&type=view&match_subgenera=1 Fossilworks]</ref>
|-
| style="background-color: {{period color|paleocene}};" | [[Paleocene]] || [[Schistes papyraces Formation]] || [[Niger]] || align=center | <ref>[http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=36596&max_interval=Paleocene&country=Niger&is_real_user=1&basic=yes&type=view&match_subgenera=1 Fossilworks]{{dead link|date=November 2024|bot=medic}}{{cbignore|bot=medic}}</ref>
|-
| style="background-color: {{period color|paleocene}};" | [[Paleocene]] || [[Umm Himar Formation]] || [[Saudi Arabia]] || align=center | <ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=140961 Fossilworks]</ref>
|-
| style="background-color: {{period color|maastrichtian}};" | [[Maastrichtian|Late Maastrichtian]] || [[Hornerstown Formation]] || [[New Jersey]] || align=center | <ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=167780 Fossilworks]</ref>
|-
| style="background-color: {{period color|maastrichtian}};" | [[Maastrichtian|Late Maastrichtian]] || [[New Egypt Formation]] || [[New Jersey]] || align=center | <ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=48570 Fossilworks]</ref>
|-
| style="background-color: {{period color|campanian}};" | [[Campanian]] || [[Shendi Formation]] || [[Sudan]] || align=center | <ref>[https://web.archive.org/web/20241126204114/http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=36596&max_interval=Cretaceous&country=Sudan&is_real_user=1&basic=yes&type=view&match_subgenera=1 Fossilworks]</ref>
|-
| style="background-color: {{period color|campanian}};" | [[Campanian]] || [[Monmouth Group]] || [[Maryland]] || align=center | <ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=127195 Fossilworks]</ref>
|-
|}

== Taxonomy ==
{{cladogram
|cladogram=
{{clade
|1={{clade
 |label=[[Crocodyliforms]]
 |1={{clade
  |label1=[[Protosuchia]]
  |label2=[[Mesoeucrocodylia]]
  |1=''[[Orthosuchus]]''
  |2={{clade
   |1=''[[Protosuchus]]''
   |2=''[[Hemiprotosuchus]]''
   }}
  |3={{clade
   |1=''[[Gobiosuchus]]''
   |2={{clade
    |1=''[[Shantungosuchus]]''
    |2=''[[Sichuanosuchus]]''
    }}
   }}
  }}
  |2={{clade
   |1=''[[Hsisosuchus]]''
   |2={{clade
    |1=''[[Baurusuchus]]''
    |2={{clade
     |1=''[[Sebecus]]''
     |2={{clade
      |1={{clade
       |1={{clade
        |1=''[[Pelagosaurus]]''
        |2={{clade
         |1=[[Teleosauridae]]
         |2=[[Metriorhynchidae]]
         }}
        }}
        |2=''[[Pholidosaurus]]''
        |3={{clade
         |1=''[[Terminonaris]]''
         |label2=[[Dyrosauridae]]
          |2={{clade
           |1=''[[Dyrosaurus]]''
           |2='''''Hyposaurus'''''
           }}
          }}
}}}}}}}}}}}}}}}}
''Hyposaurus'' was a mesosuchian crocodyliform reptile and a member of the family Dyrosauridae (Denton,.<ref name=HAST11 /> There is a disputed phylogeny with many interpretations. Some{{who|date=March 2020}} paleontologists interpret that Dyrosaurids, ''Congosaurus'', and ''Acherontisuchus'' are sister [[taxa]] of ''Hyposaurus''.<ref name=HAST11 />

== Paleobiology and paleoecology ==
''Hyposaurus'' probably lived in marine environments, mostly in shallow water and in near-shore environments.<ref name=HAST11 /><ref name=Dentonetal /> ''Hyposaurus'' had many aquatic adaptations, including pelvic and tail propulsion and light scute [[armor]].<ref name=Dentonetal /> In addition, its tail was long, both eyes were on the side of the head, and the snout was long with many{{how many|date=March 2020}} uniform teeth.<ref name=ELT25 /> The feet were not paddle-formed, a trait rather similar to modern crocodiles.<ref name=ELT25 /> The short transverse process on the caudal vertebrae implies the tail did not move vertically, indicating that ''Hyposaurus'' was not a diving animal.<ref name=ELT25 /> Moreover, Dyrosaurids generally are hypothesized to have pitch correction where the pleural cavity is pushed towards the back side to produce a more horizontal stance while submerged in water.<ref name=HAST11 /> ''Hyposaurus'' foraged in their marine environments and used the protection of the water column.<ref name=ELT25 /> [[Éric Buffetaut|Buffetaut]] proposed Dyrosaurids laid their eggs on land and only after they have fully grown moved to coastal waters.<ref name=BUFF>{{Cite journal |last=[[Éric Buffetaut|Buffetaut]] |first=Éric |title=Crocodilian remains from the Eocene of Pakistan |journal=[[Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen]] |volume=156 |pages=263–283 |year=1978}}</ref> Under this hypothesis, the young would live on land or in shallow fresh water environments. This could explain the fossil finds of smaller dyrosaurid specimens in [[Pakistan]] in [[freshwater]] sediments.<ref name=BUFF /> This ''Hyposaurus'' hypothesis has been debated as there is still a significant amount of variation among the Pakistani Dyrosaurid specimens.<ref name=HAST11 /><ref name=BUFF />

== Later research ==
In 2006 Schwarz and colleagues,<ref name=SCHWARZ>{{Cite journal |author1= Daniela Schwarz |author2=Eberhard Frey |author3=Thomas Martin |title= The Postcranial Skeleton of the Hyposaurinae (Dyrosauridae; Crocodyliformes) |journal=[[Palaeontology (journal)|Palaeontology]] |volume=49 |issue=4 |pages=695–718 |year=2006|doi=10.1111/j.1475-4983.2006.00563.x |s2cid=140648778 |url=http://doc.rero.ch/record/15208/files/PAL_E2484.pdf }}</ref> described the postcranial skeletons of new specimens of ''Hyposaurus'', focusing mostly on the vertebrae. From partial skeletons, a proatlas, atlas, axis, a third to ninth cervical vertebrae, and at least 16 dorsal, two sacral, and 45 caudal vertebrae have been reconstructed.<ref name=SCHWARZ /> The vertebrae are weakly amphicoelous, meaning both sides of the centrum are concave. The dorsal shield is made of two columns of paravertebral osteoderms and two lateral columns of accessory osteoderms. At least 12 horizontal rows of these make up the shield.<ref name=SCHWARZ />

Citing vague distinctions, Jove and colleagues,<ref name=SJ07 /> attempted to reclassify the genus ''Hyposaurus'' based on diagnostic characteristics and sort of taxonomic troubles. Flattening of the mandibular symphysis{{clarify|date=March 2020}}, used previously to distinguish between species, is not confirmed and only can be used to distinguish between ''Hyposaurus'' and ''[[Congosaurus]]''.<ref name=SJ07 /> Currently, width height ratio of teeth in different positions are being used to distinguish between species. The little variation between the species ''Hyposaurus wilsoni'' and ''Hyposaurus nopcsai'', means one of the two is a [[nomen dubium]] ([[Latin]]: "doubtful name"), although fossil evidence does suggest two species.<ref name=SJ07 /> The paper focuses on the at least 5 species of ''Hyposaurus'' or ''Congosaurus'' known from the Paleocene of the [[Iullemmeden Basin]] of Western Africa ([[Mali]], [[Niger]], [[Nigeria]]). The authors suggest using skull characteristics instead of mandibular characteristics for taxonomic distinctions because skulls are usually better preserved.<ref name=SJ07 />

A paper by Hastings and colleagues described a new skull of a dyrosaurid crocodyliform, found in the [[Cerrejón Formation]] of northern Colombia.<ref name=HASTINGS /> They used mandibular and cranial characteristics to map it onto a [[cladogram]] with ''Hyposaurus'' and other taxa. Analysis supports an African origin to Dyrosauridae, with dispersal and radiation in South America in the [[Late Cretaceous]] or very early Paleocene.<ref name=HASTINGS /> This specimen of dyrosaurid is the smallest of the family Dyrosauridae found to date, with ''Hyposaurus rogersii'' being a contender for the next smallest.<ref name=HASTINGS />

In 2016, Salih and colleagues reported the first ''Hyposaurus'' fossil found in the [[Campanian]] to [[Maastrichtian]] [[Shendi Formation]] of Sudan. It was identified as a ''Hyposaurus'' based on the flat shape of the mandible (lower jawbone) and the elliptical shape of the mandibular symphysis (median line ridge of mandible). The African member occurs in the Late Cretaceous, which supports the idea that ''Hyposaurus'' originated in Africa.<ref name="SALIH"/> This fossil is different from other specimens of ''Hyposaurus'' because it has a larger eighth alveolus (bony socket for tooth root), smaller interveolar space between the ninth and tenth alveoli, and a ridge along the dorsal side of the mandible.<ref name="SALIH"/>

== References ==
{{Portal|Paleontology}}
{{reflist}}

{{Neosuchia|N.}}
{{Taxonbar|from1=Q3495890}}

[[Category:Dyrosauridae]]
[[Category:Prehistoric pseudosuchian genera]]
[[Category:Prehistoric marine crocodylomorphs]]
[[Category:Paleocene crocodylomorphs]]
[[Category:Maastrichtian genus first appearances]]
[[Category:Paleocene genus extinctions]]
[[Category:Cretaceous–Paleogene boundary]]
[[Category:Late Cretaceous crocodylomorphs of North America]]
[[Category:Late Cretaceous crocodylomorphs of Africa]]
[[Category:Paleocene reptiles of North America]]
[[Category:Fossils of New Jersey]]
[[Category:Fossils of South Carolina]]
[[Category:Paleocene reptiles of Africa]]
[[Category:Paleocene reptiles of South America]]
[[Category:Paleogene Brazil]]
[[Category:Itaboraian]]
[[Category:Fossils of Brazil]]
[[Category:Fossil taxa described in 1849]]
[[Category:Taxa named by Richard Owen]]