Alligatoridae: Difference between revisions

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The [[family (biology)|family]] '''Alligatoridae''' of [[crocodylia]]ns includes [[alligator]]s, [[caiman]]s and their extinct relatives.
The [[Family (taxonomy)|family]] '''Alligatoridae''' of [[crocodilia]]ns includes [[alligator]]s, [[caiman]]s and their extinct relatives.


==Phylogeny==
==Phylogeny==
Line 18: Line 18:
The superfamily [[Alligatoroidea]] includes all crocodilians (fossil and extant) that are more closely related to the American alligator than to either the [[Nile crocodile]] or the [[gharial]].<ref>{{cite journal |last=Brochu |first=Christopher A. |title=Phylogenetic approaches toward crocodylian history |journal=Annual Review of Earth and Planetary Sciences |volume=31 |year=2003 |pages=357–97 |doi=10.1146/annurev.earth.31.100901.141308 }}</ref> This is a [[stem-based taxon|stem-based]] definition for [[alligators]], and is more inclusive than the [[crown group]] Alligatoridae.<ref name="LeeYates2018">{{cite journal | author=Michael S. Y. Lee |author2=Adam M. Yates |date=27 June 2018 |title=Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil |journal=Proceedings of the Royal Society B: Biological Sciences |volume=285 |issue=1881 |pmid=30051855| doi=10.1098/rspb.2018.1071 |pmc=6030529 |doi-access=free}}</ref>  As a crown group, Alligatoridae only includes the [[last common ancestor]] of all [[extant taxon|extant]] (living) alligators, caimans, and their descendants (living or [[extinct]]), whereas Alligatoroidea, as a stem-based group, also includes more [[basal (phylogenetics)|basal]] extinct alligator ancestors that are more closely related to living alligators than to [[crocodiles]] or [[gavialids]]. When considering only living taxa ([[neontology]]), Alligatoroidea and Alligatoridae contain the same species.
The superfamily [[Alligatoroidea]] includes all crocodilians (fossil and extant) that are more closely related to the American alligator than to either the [[Nile crocodile]] or the [[gharial]].<ref>{{cite journal |last=Brochu |first=Christopher A. |title=Phylogenetic approaches toward crocodylian history |journal=Annual Review of Earth and Planetary Sciences |volume=31 |year=2003 |pages=357–97 |doi=10.1146/annurev.earth.31.100901.141308 }}</ref> This is a [[stem-based taxon|stem-based]] definition for [[alligators]], and is more inclusive than the [[crown group]] Alligatoridae.<ref name="LeeYates2018">{{cite journal | author=Michael S. Y. Lee |author2=Adam M. Yates |date=27 June 2018 |title=Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil |journal=Proceedings of the Royal Society B: Biological Sciences |volume=285 |issue=1881 |pmid=30051855| doi=10.1098/rspb.2018.1071 |pmc=6030529 |doi-access=free}}</ref>  As a crown group, Alligatoridae only includes the [[last common ancestor]] of all [[extant taxon|extant]] (living) alligators, caimans, and their descendants (living or [[extinct]]), whereas Alligatoroidea, as a stem-based group, also includes more [[basal (phylogenetics)|basal]] extinct alligator ancestors that are more closely related to living alligators than to [[crocodiles]] or [[gavialids]]. When considering only living taxa ([[neontology]]), Alligatoroidea and Alligatoridae contain the same species.


The simplified [[cladogram]] below shows Alligatoridae's relationships to other [[extant taxon|extant]] (living) crocodilians.<ref name="LeeYates2018"/><ref name="Rio2021">{{cite journal |last1=Rio |first1=Jonathan P. |last2=Mannion |first2=Philip D. |date=6 September 2021 |title=Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem |journal=[[PeerJ]] |volume=9 |page=e12094 |doi=10.7717/peerj.12094 |pmid=34567843 |pmc=8428266 |doi-access=free}}</ref><ref name="Hekkala2021">{{Cite journal |last1=Hekkala |first1=E. |last2=Gatesy |first2=J. |last3=Narechania |first3=A. |last4=Meredith |first4=R. |last5=Russello |first5=M. |last6=Aardema |first6=M. L. |last7=Jensen |first7=E. |last8=Montanari |first8=S. |last9=Brochu |first9=C. |last10=Norell |first10=M. |last11=Amato |first11=G. |date=2021-04-27 |title=Paleogenomics illuminates the evolutionary history of the extinct Holocene "horned" crocodile of Madagascar, ''Voay robustus'' |journal=[[Communications Biology]] |language=en |volume=4 |issue=1 |page=505 |doi=10.1038/s42003-021-02017-0 |pmid=33907305 |pmc=8079395 |issn=2399-3642 |doi-access=free}}</ref>
The simplified [[cladogram]] below shows Alligatoridae's relationships to other [[extant taxon|extant]] (living) crocodilians.<ref name="LeeYates2018"/><ref name="Rio2021">{{cite journal |last1=Rio |first1=Jonathan P. |last2=Mannion |first2=Philip D. |date=6 September 2021 |title=Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem |journal=[[PeerJ]] |volume=9 |article-number=e12094 |doi=10.7717/peerj.12094 |pmid=34567843 |pmc=8428266 |doi-access=free}}</ref><ref name="Hekkala2021">{{Cite journal |last1=Hekkala |first1=E. |last2=Gatesy |first2=J. |last3=Narechania |first3=A. |last4=Meredith |first4=R. |last5=Russello |first5=M. |last6=Aardema |first6=M. L. |last7=Jensen |first7=E. |last8=Montanari |first8=S. |last9=Brochu |first9=C. |last10=Norell |first10=M. |last11=Amato |first11=G. |date=2021-04-27 |title=Paleogenomics illuminates the evolutionary history of the extinct Holocene "horned" crocodile of Madagascar, ''Voay robustus'' |journal=[[Communications Biology]] |language=en |volume=4 |issue=1 |page=505 |doi=10.1038/s42003-021-02017-0 |pmid=33907305 |pmc=8079395 |issn=2399-3642 |doi-access=free}}</ref>
{{clade| style=font-size:85%;line-height:85%
{{clade| style=font-size:85%;line-height:85%
|label1='''[[Crocodylia]]'''
|label1='''[[Crocodylia]]'''
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     |2=''[[Tomistoma]]'' [[File:Tomistoma schlegelii. white background.JPG|90 px]] }} }} }} }} }} }}
     |2=''[[Tomistoma]]'' [[File:Tomistoma schlegelii. white background.JPG|90 px]] }} }} }} }} }} }}


Alligatoridae contains eight living species: two alligators within [[Alligatorinae]], and the six caimans of [[Caimaninae]]. [[Phylogenetic]] studies using molecular DNA consistently resolve their relationships as follows:<ref>{{Cite journal |last1=Bittencourt |first1=Pedro Senna |last2=Campos |first2=Zilca |last3=Muniz |first3=Fabio de Lima |last4=Marioni |first4=Boris |last5=Souza |first5=Bruno Campos |last6=Da Silveira |first6=Ronis |last7=de Thoisy |first7=Benoit |last8=Hrbek |first8=Tomas |last9=Farias |first9=Izeni Pires |date=22 March 2019 |title=Evidence of cryptic lineages within a small South American crocodilian: the Schneider’s dwarf caiman ''Paleosuchus trigonatus'' (Alligatoridae: Caimaninae) |journal=[[PeerJ]] |volume=7 |page=e6580 |doi=10.7717/peerj.6580 |pmid=30931177 |pmc=6433001 |doi-access=free }}</ref>
Alligatoridae contains eight living species: two alligators within [[Alligatorinae]], and the six caimans of [[Caimaninae]]. [[Phylogenetic]] studies using molecular DNA consistently resolve their relationships as follows:<ref>{{Cite journal |last1=Bittencourt |first1=Pedro Senna |last2=Campos |first2=Zilca |last3=Muniz |first3=Fabio de Lima |last4=Marioni |first4=Boris |last5=Souza |first5=Bruno Campos |last6=Da Silveira |first6=Ronis |last7=de Thoisy |first7=Benoit |last8=Hrbek |first8=Tomas |last9=Farias |first9=Izeni Pires |date=22 March 2019 |title=Evidence of cryptic lineages within a small South American crocodilian: the Schneider's dwarf caiman ''Paleosuchus trigonatus'' (Alligatoridae: Caimaninae) |journal=[[PeerJ]] |volume=7 |article-number=e6580 |doi=10.7717/peerj.6580 |pmid=30931177 |pmc=6433001 |doi-access=free }}</ref>
{{clade
{{clade
  |label1='''Alligatoridae'''
  |label1='''Alligatoridae'''
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   |1={{clade
   |1={{clade
     |1=''Paleosuchus palpebrosus'' [[Cuvier's dwarf caiman]]
     |1=''Paleosuchus palpebrosus'' [[Cuvier's dwarf caiman]]
     |2=''Paleosuchus trigonatus'' [[Schneider's dwarf caiman]] }}
     |2=''Paleosuchus trigonatus'' [[Smooth-fronted caiman]] }}
   |label2=[[Jacarea]]
   |label2=[[Jacarea]]
   |2={{clade
   |2={{clade
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   |2=''Alligator mississippiensis'' [[American alligator]] }} }} }}
   |2=''Alligator mississippiensis'' [[American alligator]] }} }} }}


The below detailed cladogram shows one proposal for the internal relationships within Alligatoridae including fossil species, based on [[morphology (biology)|morphological]] analysis<ref name="Bona2018">{{Cite journal|author1=Paula Bona |author2=Martín D. Ezcurra |author3=Francisco Barrios |author4=María V. Fernandez Blanco |year=2018 |title=A new Palaeocene crocodylian from southern Argentina sheds light on the early history of caimanines |journal=Proceedings of the Royal Society B: Biological Sciences |volume=285 |issue=1885 |page=20180843 |doi=10.1098/rspb.2018.0843 |pmid=30135152 |pmc=6125902 }}</ref> (although the exact alligatoroid phylogeny is still disputed).
The below detailed cladogram shows one proposal for the internal relationships within Alligatoridae including fossil species, based on [[morphology (biology)|morphological]] analysis<ref name="Bona2018">{{Cite journal|author1=Paula Bona |author2=Martín D. Ezcurra |author3=Francisco Barrios |author4=María V. Fernandez Blanco |year=2018 |title=A new Palaeocene crocodylian from southern Argentina sheds light on the early history of caimanines |journal=Proceedings of the Royal Society B: Biological Sciences |volume=285 |issue=1885 |article-number=20180843 |doi=10.1098/rspb.2018.0843 |pmid=30135152 |pmc=6125902 }}</ref> (although the exact alligatoroid phylogeny is still disputed).
{{clade| style=font-size:85%;line-height:85%
{{clade| style=font-size:85%;line-height:85%
|label1='''[[Alligatoroidea]]'''
|label1='''[[Alligatoroidea]]'''
Line 172: Line 172:


==Evolution==
==Evolution==
The superfamily [[Alligatoroidea]] is thought to have split from the crocodile-gharial lineage in the [[late Cretaceous]], about 87 million years ago.<ref name="Oaks2011" /><ref name="Pan2020" /> ''[[Leidyosuchus]]'' of [[Alberta]] is among the earliest known genera. Fossil alligatoroids have been found throughout Eurasia as land bridges across both the North Atlantic and the [[Bering Strait]] have connected North America to Eurasia during the Cretaceous, [[Paleogene]], and [[Neogene]] periods. Alligators and caimans split in North America during the early Tertiary or late Cretaceous (about 53 million<ref name="Pan2020">{{cite journal|last10= Wu|first10=X.-B.|last9= Zhang|first9=B.-W.|last8= Deng|first8=Y.-P.|last7= Ouyang|first7=J.-H.|last6= Jiang|first6=X.-Y.|last5= Lee|first5=P.-S.|last4= Yan|first4=P.|last3= Zhang|first3=H.-B.|last2= Miao|first2=J.-S.|last1= Pan|first1=T.|title= Near-complete phylogeny of extant Crocodylia (Reptilia) using mitogenome-based data|journal= Zoological Journal of the Linnean Society |year= 2020|volume=191|issue=4|pages=1075–1089|doi= 10.1093/zoolinnean/zlaa074}}</ref> to about 65 million years ago<ref name="Oaks2011">{{cite journal|last1= Oaks|first1= J.R.|title=A time-calibrated species tree of Crocodylia reveals a recent radiation of the true crocodiles |journal= Evolution |volume= 65|issue= 11|year= 2011|pages= 3285–3297|doi= 10.1111/j.1558-5646.2011.01373.x|pmid= 22023592|s2cid= 7254442|doi-access= free}}</ref>) and the latter reached South America by the Paleogene, before the closure of the [[Isthmus of Panama]] during the Neogene period. The Chinese alligator split from the American alligator about 33 million years ago<ref name="Pan2020" /> and likely descended from a lineage that crossed [[Beringia|the Bering land bridge]] during the Neogene. The modern American alligator is well represented in the fossil record of the [[Pleistocene]].<ref>{{cite journal|doi= 10.2307/3889340|title= Phylogenetics, Taxonomy, and Historical Biogeography of Alligatoroidea|last=Brochu|first=Christopher A.|journal=Society of Vertebrate Paleontology Memoir|volume=6|year=1999|pages=9–100|jstor=3889340}}</ref> The alligator's full [[mitochondrial genome]] was sequenced in the 1990s.<ref>{{cite journal|author1=Janke, A. |author2=Arnason, U. |year=1997|title=The complete mitochondrial genome of Alligator mississippiensis and the separation between recent archosauria (birds and crocodiles)|journal=Molecular Biology and Evolution|volume= 14|issue= 12|pages= 1266–72|pmid= 9402737|doi= 10.1093/oxfordjournals.molbev.a025736|doi-access= free}}</ref> The full [[genome]], published in 2014, suggests that the alligator evolved much more slowly than mammals and birds.<ref>{{cite journal |vauthors=Green RE, Braun EL, Armstrong J, Earl D, Nguyen N, Hickey G, Vandewege MW, St John JA, Capella-Gutiérrez S, Castoe TA, Kern C, Fujita MK, Opazo JC, Jurka J, Kojima KK, Caballero J, Hubley RM, Smit AF, Platt RN, Lavoie CA, Ramakodi MP, Finger JW, Suh A, Isberg SR, Miles L, Chong AY, Jaratlerdsiri W, Gongora J, Moran C, Iriarte A, McCormack J, Burgess SC, Edwards SV, Lyons E, Williams C, Breen M, Howard JT, Gresham CR, Peterson DG, Schmitz J, Pollock DD, Haussler D, Triplett EW, Zhang G, Irie N, Jarvis ED, Brochu CA, Schmidt CJ, McCarthy FM, Faircloth BC, Hoffmann FG, Glenn TC, Gabaldón T, Paten B, Ray DA |title=Three crocodilian genomes reveal ancestral patterns of evolution among archosaurs |journal=Science |volume=346 |issue=6215 |page=1254449 |year=2014 |pmid=25504731 |pmc=4386873 |doi=10.1126/science.1254449 }}</ref>
The superfamily [[Alligatoroidea]] is thought to have split from the crocodile-gharial lineage in the [[late Cretaceous]], about 87 million years ago.<ref name="Oaks2011" /><ref name="Pan2020" /> ''[[Leidyosuchus]]'' of [[Alberta]] is among the earliest known genera. Fossil alligatoroids have been found throughout Eurasia as land bridges across both the North Atlantic and the [[Bering Strait]] have connected North America to Eurasia during the Cretaceous, [[Paleogene]], and [[Neogene]] periods. Alligators and caimans split in North America during the early Tertiary or late Cretaceous (about 53 million<ref name="Pan2020">{{cite journal|last10= Wu|first10=X.-B.|last9= Zhang|first9=B.-W.|last8= Deng|first8=Y.-P.|last7= Ouyang|first7=J.-H.|last6= Jiang|first6=X.-Y.|last5= Lee|first5=P.-S.|last4= Yan|first4=P.|last3= Zhang|first3=H.-B.|last2= Miao|first2=J.-S.|last1= Pan|first1=T.|title= Near-complete phylogeny of extant Crocodylia (Reptilia) using mitogenome-based data|journal= Zoological Journal of the Linnean Society |year= 2020|volume=191|issue=4|pages=1075–1089|doi= 10.1093/zoolinnean/zlaa074}}</ref> to about 65 million years ago<ref name="Oaks2011">{{cite journal|last1= Oaks|first1= J.R.|title=A time-calibrated species tree of Crocodylia reveals a recent radiation of the true crocodiles |journal= Evolution |volume= 65|issue= 11|year= 2011|pages= 3285–3297|doi= 10.1111/j.1558-5646.2011.01373.x|pmid= 22023592|s2cid= 7254442|doi-access= free}}</ref>) and the latter reached South America by the Paleogene, before the closure of the [[Isthmus of Panama]] during the Neogene period. The Chinese alligator split from the American alligator about 33 million years ago<ref name="Pan2020" /> and likely descended from a lineage that crossed [[Beringia|the Bering land bridge]] during the Neogene. The modern American alligator is well represented in the fossil record of the [[Pleistocene]].<ref>{{cite journal|doi= 10.2307/3889340|title= Phylogenetics, Taxonomy, and Historical Biogeography of Alligatoroidea|last=Brochu|first=Christopher A.|journal=Society of Vertebrate Paleontology Memoir|volume=6|year=1999|pages=9–100|jstor=3889340}}</ref> The alligator's full [[mitochondrial genome]] was sequenced in the 1990s.<ref>{{cite journal|author1=Janke, A. |author2=Arnason, U. |year=1997|title=The complete mitochondrial genome of Alligator mississippiensis and the separation between recent archosauria (birds and crocodiles)|journal=Molecular Biology and Evolution|volume= 14|issue= 12|pages= 1266–72|pmid= 9402737|doi= 10.1093/oxfordjournals.molbev.a025736|doi-access= free}}</ref> The full [[genome]], published in 2014, suggests that the alligator evolved much more slowly than mammals and birds.<ref>{{cite journal |vauthors=Green RE, Braun EL, Armstrong J, Earl D, Nguyen N, Hickey G, Vandewege MW, St John JA, Capella-Gutiérrez S, Castoe TA, Kern C, Fujita MK, Opazo JC, Jurka J, Kojima KK, Caballero J, Hubley RM, Smit AF, Platt RN, Lavoie CA, Ramakodi MP, Finger JW, Suh A, Isberg SR, Miles L, Chong AY, Jaratlerdsiri W, Gongora J, Moran C, Iriarte A, McCormack J, Burgess SC, Edwards SV, Lyons E, Williams C, Breen M, Howard JT, Gresham CR, Peterson DG, Schmitz J, Pollock DD, Haussler D, Triplett EW, Zhang G, Irie N, Jarvis ED, Brochu CA, Schmidt CJ, McCarthy FM, Faircloth BC, Hoffmann FG, Glenn TC, Gabaldón T, Paten B, Ray DA |title=Three crocodilian genomes reveal ancestral patterns of evolution among archosaurs |journal=Science |volume=346 |issue=6215 |article-number=1254449 |year=2014 |pmid=25504731 |pmc=4386873 |doi=10.1126/science.1254449 }}</ref>


== True alligators ==
== True alligators ==
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**** † ''[[Alligator prenasalis]]''
**** † ''[[Alligator prenasalis]]''
**** ''Alligator sinensis'', [[Chinese alligator]]
**** ''Alligator sinensis'', [[Chinese alligator]]
**** † ''[[Alligator munensis]]''
**** † ''[[Alligator thomsoni]]''
**** † ''[[Alligator thomsoni]]''
*** Genus † ''[[Allognathosuchus]]''
*** Genus † ''[[Allognathosuchus]]''

Latest revision as of 12:44, 20 May 2026

Alligatoridae
File:Florida Alligator.jpg
American alligator (Alligator mississippiensis)
Scientific classification e
Missing taxonomy template (fix): Alligatoridae
Subfamilies

Template:Taxonbar/candidate

The family Alligatoridae of crocodilians includes alligators, caimans and their extinct relatives.

Phylogeny

File:Alligator olseni.jpg
A. olseni fore limb
File:Alligator prenasalis.JPG
Alligator prenasalis fossil

The superfamily Alligatoroidea includes all crocodilians (fossil and extant) that are more closely related to the American alligator than to either the Nile crocodile or the gharial.[1] This is a stem-based definition for alligators, and is more inclusive than the crown group Alligatoridae.[2] As a crown group, Alligatoridae only includes the last common ancestor of all extant (living) alligators, caimans, and their descendants (living or extinct), whereas Alligatoroidea, as a stem-based group, also includes more basal extinct alligator ancestors that are more closely related to living alligators than to crocodiles or gavialids. When considering only living taxa (neontology), Alligatoroidea and Alligatoridae contain the same species.

The simplified cladogram below shows Alligatoridae's relationships to other extant (living) crocodilians.[2][3][4]

Crocodylia
Alligatoroidea
 

LeidyosuchusTemplate:Extinct

 
 
DiplocynodontinaeTemplate:Extinct

DiplocynodonTemplate:Extinct

 
Globidonta
 

extinct basal Alligatoroid GlobidontansTemplate:Extinct

 
Alligatoridae
Caimaninae
 
 

Caiman File:Caiman crocodilus llanos white background.JPG

 
 

Melanosuchus File:Melanosuchus niger white background.jpg

 
 
 

Paleosuchus File:Dwarf Caiman white background.jpg

 
(stem-based group)
Alligatorinae

Alligator File:Alligator white background.jpg

(stem-based group)
(crown group)
(stem-based group)
 
(stem-based group)
 
 

extinct basal CrocodiliansTemplate:Extinct (possibly including MekosuchinaeTemplate:Extinct)

 
Longirostres
Crocodyloidea
 

extinct basal crocodilesTemplate:Extinct

 
 

Crocodylidae (crown group) File:Siamese Crocodile white background.jpg

 
(stem-based group)
Gavialoidea
 

extinct basal GavialoidsTemplate:Extinct

 
Gavialidae
 

Gavialis File:Gavialis gangeticus (Gharial, Gavial) white background.jpg

 
 

Tomistoma File:Tomistoma schlegelii. white background.JPG

 
(crown group)
(stem-based group)
(crown group)
 
(crown group)

Alligatoridae contains eight living species: two alligators within Alligatorinae, and the six caimans of Caimaninae. Phylogenetic studies using molecular DNA consistently resolve their relationships as follows:[5]

Alligatoridae
Caimaninae
 
 

Paleosuchus palpebrosus Cuvier's dwarf caiman

 
 

Paleosuchus trigonatus Smooth-fronted caiman

 
 
Jacarea
 
 
 

Caiman crocodilus Spectacled caiman

 
 

Caiman yacare Yacare caiman

 
 
 

Caiman latirostris Broad-snouted caiman

 
 
 

Melanosuchus niger Black caiman

 
 
 
Alligatorinae
 

Alligator sinensis Chinese alligator

 
 

Alligator mississippiensis American alligator

 
 
 

The below detailed cladogram shows one proposal for the internal relationships within Alligatoridae including fossil species, based on morphological analysis[6] (although the exact alligatoroid phylogeny is still disputed).

Alligatoroidea
 

LeidyosuchusTemplate:Extinct

 
 
 

DiplocynodonTemplate:Extinct

 
Alligatoridae
Alligatorinae
 

CeratosuchusTemplate:Extinct

 
 

AllognathosuchusTemplate:Extinct

 
 

NavajosuchusTemplate:Extinct

 
 

ArambourgiaTemplate:Extinct

 
 

ProcaimanoideaTemplate:Extinct

 
 
 

WannaganosuchusTemplate:Extinct

 
 
 

Alligator prenasalisTemplate:Extinct

 
 
 

Alligator mcgrewiTemplate:Extinct

 
 
 

Alligator olseniTemplate:Extinct

 
 
 

Alligator sinensis Chinese alligator

 
 
 

CulebrasuchusTemplate:Extinct

 
 
 

Alligator mississippiensis American alligator

 
 

Alligator mefferdiTemplate:Extinct

 
 

Alligator thomsoniTemplate:Extinct

 
 
 
 
 
 
 
 
(stem-based group)
Caimaninae
 
 

StangerochampsaTemplate:Extinct

 
 

AlbertochampsaTemplate:Extinct

 
 

BrachychampsaTemplate:Extinct

 
 
 
 

ProtocaimanTemplate:Extinct

 
 
 

GnatusuchusTemplate:Extinct

 
 
 

GlobidentosuchusTemplate:Extinct

 
 
 
 

EocaimanTemplate:Extinct

 
 

NotocaimanTemplate:Extinct

 
 
 
 

KuttanacaimanTemplate:Extinct

 
 
 
 

PurussaurusTemplate:Extinct

 
 

MourasuchusTemplate:Extinct

 
 
 
 
 

NecrosuchusTemplate:Extinct

 
 

TsoabichiTemplate:Extinct

 
 
 

Paleosuchus trigonatus Smooth-fronted caiman

 
 

Paleosuchus palpebrosus Cuvier's dwarf caiman

 
 
 
 
 

CentenariosuchusTemplate:Extinct

 
 
 
 

Caiman latirostris Broad-snouted caiman

 
 

Melanosuchus niger Black caiman

 
 
 
 
 

Caiman yacare Yacare caiman

 
 

Caiman crocodilus Spectacled caiman

 
 
 
 

Caiman brevirostrisTemplate:Extinct

 
 
 

La Venta CaimanTemplate:Extinct

 
 

Caiman wannlangstoniTemplate:Extinct

 
 
 
 
 
 
 
 
 
 
 
 
 
(stem-based group)
(crown group)
 
(stem-based group)

Evolution

The superfamily Alligatoroidea is thought to have split from the crocodile-gharial lineage in the late Cretaceous, about 87 million years ago.[7][8] Leidyosuchus of Alberta is among the earliest known genera. Fossil alligatoroids have been found throughout Eurasia as land bridges across both the North Atlantic and the Bering Strait have connected North America to Eurasia during the Cretaceous, Paleogene, and Neogene periods. Alligators and caimans split in North America during the early Tertiary or late Cretaceous (about 53 million[8] to about 65 million years ago[7]) and the latter reached South America by the Paleogene, before the closure of the Isthmus of Panama during the Neogene period. The Chinese alligator split from the American alligator about 33 million years ago[8] and likely descended from a lineage that crossed the Bering land bridge during the Neogene. The modern American alligator is well represented in the fossil record of the Pleistocene.[9] The alligator's full mitochondrial genome was sequenced in the 1990s.[10] The full genome, published in 2014, suggests that the alligator evolved much more slowly than mammals and birds.[11]

True alligators

The lineage including alligators proper (Alligatorinae) occurs in the fluvial deposits of the age of the Upper Chalk in Europe, where they died out in the Pliocene age. The true alligators are today represented by two species, A. mississippiensis in the southeastern United States which can grow to 15.6 feet (4.8 m) and weigh 1,000 pounds (450 kg),[12] with unverified sizes of up to 19.2 feet (5.9 m), and the small A. sinensis in the Yangtze River, China, which grows to an average of 5 feet (1.5 m). Their name derives from the Spanish el lagarto, which means "the lizard".

Caimans

File:Caiman crocodilus Tropicario 2.JPG
C. crocodilus at the Helsinki Tropicario Zoo aquarium in Helsinki, Finland in 2010

In Central and South America, the alligator family is represented by six species of the subfamily Caimaninae, which differ from the alligator by the absence of a bony septum between the nostrils, and having ventral armour composed of overlapping bony scutes, each of which is formed of two parts united by a suture. Besides the three species in Caiman, the smooth-fronted caimans in genus Paleosuchus and the black caiman in Melanosuchus are described. Caimans tend to be more agile and crocodile-like in their movements, and have longer, sharper teeth than alligators.[13]

C. crocodilus, the spectacled caiman, has the widest distribution, from southern Mexico to the northern half of Argentina, and grows to a modest size of about 2.2 m (7.2 ft). The largest is the near-threatened Melanosuchus niger, the jacaré-açu or large or black caiman of the Amazon River basin. Black caimans grow to 4.4 m (14.5 ft), with the unverified size of up to 5.7 m (19 ft). The black caiman and American alligator are the only members of the alligator family that pose the same danger to humans as the larger species of the crocodile family.

Although caimans have not been studied in depth, scientists have learned their mating cycles (previously thought to be spontaneous or year-round) are linked to the rainfall cycles and the river levels, which increases chances of survival for their offspring.

Taxonomy

See also: List of crocodilians

† = extinct

File:Crocnest.JPG
An alligator nest at Everglades National Park, Florida, United States
File:Spectacled caiman by Keven Law.jpg
Spectacled caiman head
File:Wikipedia-7744.jpg
Black caiman, Jauaperi River, Amazonia
File:Caïman de Schneider (Paleosuchus trigonatus).jpg
Head of smooth-fronted caiman

References

  1. ↑ Brochu, Christopher A. (2003). "Phylogenetic approaches toward crocodylian history". Annual Review of Earth and Planetary Sciences. 31: 357–97. doi:10.1146/annurev.earth.31.100901.141308.
  2. ↑ 2.0 2.1 Michael S. Y. Lee; Adam M. Yates (27 June 2018). "Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil". Proceedings of the Royal Society B: Biological Sciences. 285 (1881). doi:10.1098/rspb.2018.1071. PMC 6030529. PMID 30051855.
  3. ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
  4. ↑ Hekkala, E.; Gatesy, J.; Narechania, A.; Meredith, R.; Russello, M.; Aardema, M. L.; Jensen, E.; Montanari, S.; Brochu, C.; Norell, M.; Amato, G. (2021-04-27). "Paleogenomics illuminates the evolutionary history of the extinct Holocene "horned" crocodile of Madagascar, Voay robustus". Communications Biology. 4 (1): 505. doi:10.1038/s42003-021-02017-0. ISSN 2399-3642. PMC 8079395. PMID 33907305.
  5. ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
  6. ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
  7. ↑ 7.0 7.1 Oaks, J.R. (2011). "A time-calibrated species tree of Crocodylia reveals a recent radiation of the true crocodiles". Evolution. 65 (11): 3285–3297. doi:10.1111/j.1558-5646.2011.01373.x. PMID 22023592. S2CID 7254442.
  8. ↑ 8.0 8.1 8.2 Pan, T.; Miao, J.-S.; Zhang, H.-B.; Yan, P.; Lee, P.-S.; Jiang, X.-Y.; Ouyang, J.-H.; Deng, Y.-P.; Zhang, B.-W.; Wu, X.-B. (2020). "Near-complete phylogeny of extant Crocodylia (Reptilia) using mitogenome-based data". Zoological Journal of the Linnean Society. 191 (4): 1075–1089. doi:10.1093/zoolinnean/zlaa074.
  9. ↑ Brochu, Christopher A. (1999). "Phylogenetics, Taxonomy, and Historical Biogeography of Alligatoroidea". Society of Vertebrate Paleontology Memoir. 6: 9–100. doi:10.2307/3889340. JSTOR 3889340.
  10. ↑ Janke, A.; Arnason, U. (1997). "The complete mitochondrial genome of Alligator mississippiensis and the separation between recent archosauria (birds and crocodiles)". Molecular Biology and Evolution. 14 (12): 1266–72. doi:10.1093/oxfordjournals.molbev.a025736. PMID 9402737.
  11. ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
  12. ↑ "American alligator". animals.nationalgeographic.com. National Geographic Society.
  13. ↑ Guggisberg, C.A.W. (1972). Crocodiles: Their Natural History, Folklore, and Conservation. David & Charles. p. 195. ISBN 978-0-7153-5272-4.
  14. ↑ Adam P. Cossette (2020). "A new species of Bottosaurus (Alligatoroidea: Caimaninae) from the Black Peaks Formation (Palaeocene) of Texas indicates an early radiation of North American caimanines". Zoological Journal of the Linnean Society. 191: 276–301. doi:10.1093/zoolinnean/zlz178.

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