View source for Diplocynodon

{{Short description|Extinct genus of reptiles}}
{{Automatic taxobox
| taxon = Diplocynodon
| display_parents = 3
| image = Diplocynodon ratelii.JPG
| image_caption = ''Diplocynodon ratelii''
| fossil_range = [[Paleocene]] - [[Middle Miocene]], {{fossil range|59.2|13.8|ref=<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 |pages=e12094 |doi=10.7717/peerj.12094 |pmid=34567843 |pmc=8428266 |doi-access=free}}</ref>}}
| authority = Pomel, 1847
| parent_authority = Brochu, 1999
| subdivision_ranks = Species
| subdivision = 
*{{extinct}}''D.moraviensis''
*{{extinct}}''D. darwini'' <small>(Ludvig, 1877)</small>
*{{extinct}}''D. deponiae'' <small>(Frey, Laemmert & Riess, 1987)</small><ref name=Rossman>{{cite journal | last1 = Rossmann | first1 = T. | last2 = Blume | first2 = M. | year = 1999 | title = Die Krokodil-Fauna der Fossillagerstätte Grube Messel | journal = Ein aktueller Überblick., Natur und Museum, Frankfurt am Main | volume = 129 | issue = 9| pages = 261–270 }}</ref><ref name=Baryphracta>{{cite journal |author1=Massimo Delfino |author2=Thierry Smith |year=2012 |title=Reappraisal of the morphology and phylogenetic relationships of the middle Eocene alligatoroid ''Diplocynodon deponiae'' (Frey, Laemmert, and Riess, 1987) based on a three-dimensional specimen |journal=Journal of Vertebrate Paleontology |volume=32 |issue=6 |pages=1358–1369 |doi=10.1080/02724634.2012.699484 |bibcode=2012JVPal..32.1358D |s2cid=84977303 }}</ref>
*{{extinct}}''D. elavericus'' <small>Martin, [[2010 in paleontology|2010]]</small>
*{{extinct}}''D. gervaisi''
*{{extinct}}''D. hantoniensis'' <small>(Wood, 1846)</small>
*{{extinct}}''D. levantinicum'' <small>Huene & Nikoloff, 1963</small>
*{{extinct}}''D. kochi'' <small>(Venczel & Codrea, 2022)</small><ref>{{Cite journal|vauthors=Venczel M, Codrea VA |title=A new late Eocene alligatoroid crocodyliform from Transylvania |journal=Comptes Rendus Palevol |year=2022 |volume=21 |issue=20 |pages=411–429 |doi=10.5852/cr-palevol2022v21a20 |s2cid=248879850 |doi-access=free }}</ref>
*{{extinct}}''D. muelleri'' <small>(Kälin, 1936)</small><ref name=Hispanochampsa>{{cite journal |author1=Paolo Pirasa |author2=Angela D. Buscalionib |year=2006 |title=''Diplocynodon muelleri'' comb. nov., an Oligocene diplocynodontine alligatoroid from Catalonia (Ebro Basin, Lleida Province, Spain) |journal=Journal of Vertebrate Paleontology |volume=26 |issue=3 |pages=608–620 |doi=10.1671/0272-4634(2006)26[608:DMCNAO]2.0.CO;2 |s2cid=86181419 |url=http://doc.rero.ch/record/15681/files/PAL_E1171.pdf }}</ref>
*{{extinct}}''D. ratelii'' <small>Pomel, 1847 ([[type species|type]])</small>
*{{extinct}}''D. tormis''
*{{extinct}}''D. ungeri'' <small>(Prangner, 1845)</small>
| synonyms = * ''Baryphracta'' <small>Frey, Laemmert & Riess, 1987</small><ref name=Rossman/><ref name=Baryphracta/>
* ''Enneodon'' <small>Pranger, 1845</small>
* ''Hispanochampsa'' <small>Kälin, 1936</small><ref>{{Cite journal | last1 = Kälin | first1 = J. A. | year = 1936 | title = ''Hispanochampsa mülleri'' nov. gen. nov. sp. | journal = Abh. Schweizer. Palaeontol. Gesellschaft | volume = 58 | pages = 1–39 }}</ref><ref name=Hispanochampsa/>
* ''Saurocainus''
}}

'''''Diplocynodon''''' is an [[extinct]] [[genus]] of [[eusuchian]], either an [[Alligatoroidea|alligatoroid]] [[Crocodilia|crocodilian]] or a stem-group crocodilian, that lived during the [[Paleocene]] to [[Middle Miocene]] in [[Europe]]. Some species may have reached lengths of {{Convert|3|m|ft}},<ref name=":0">{{Cite journal |last1=Massonne |first1=Tobias |last2=Böhme |first2=Madelaine |date=2022-11-09 |title=Re-evaluation of the morphology and phylogeny of Diplocynodon levantinicum Huene & Nikoloff, 1963 and the stratigraphic age of the West Maritsa coal field (Upper Thrace Basin, Bulgaria) |journal=PeerJ |language=en |volume=10 |pages=e14167 |doi=10.7717/peerj.14167 |pmid=36389401 |issn=2167-8359|pmc=9653056 |doi-access=free }}</ref> while others probably did not exceed {{Convert|1|m|ft}}.<ref>{{Cite journal |last1=Delfino |first1=Massimo |last2=Smith |first2=Thierry |date=November 2012 |title=Reappraisal of the morphology and phylogenetic relationships of the middle Eocene alligatoroid Diplocynodon deponiae (Frey, Laemmert, and Riess, 1987) based on a three-dimensional specimen |url=http://www.tandfonline.com/doi/abs/10.1080/02724634.2012.699484 |journal=Journal of Vertebrate Paleontology |language=en |volume=32 |issue=6 |pages=1358–1369 |doi=10.1080/02724634.2012.699484 |bibcode=2012JVPal..32.1358D |s2cid=84977303 |issn=0272-4634|url-access=subscription }}</ref> They are almost exclusively found in freshwater environments.<ref>Sabău I, Venczel M, Codrea VA, Bordeianu M. 2021. ''Diplocynodon'': a salt water eocene crocodile from Transylvania? ''North-Western Journal of Zoology'' 17(1):117-121</ref> The various species are thought to have been opportunistic aquatic predators.<ref>{{Cite journal |last1=Tütken |first1=Thomas |last2=Absolon |first2=Julia |date=March 2015 |title=Late Oligocene ambient temperatures reconstructed by stable isotope analysis of terrestrial and aquatic vertebrate fossils of Enspel, Germany |url=http://link.springer.com/10.1007/s12549-014-0183-7 |journal=Palaeobiodiversity and Palaeoenvironments |language=en |volume=95 |issue=1 |pages=17–31 |doi=10.1007/s12549-014-0183-7 |bibcode=2015PdPe...95...17T |s2cid=129654808 |issn=1867-1594|url-access=subscription }}</ref>

In the nineteenth century, ''D. steineri'' was named from [[Styria]], [[Austria]] and ''D. styriacus'' was named from [[Austria]] and [[France]]. A third Austrian species, ''Enneodon ungeri'', was placed in its own genus. The Austrian and French species of ''Diplocynodon'' were [[Synonym (taxonomy)|synonymized]] with ''E. ungeri'' in 2011, and because the name ''Diplocynodon'' has priority over ''Enneodon'', the species is now called ''D. ungeri''.<ref name=Enneodon>{{cite journal |author1=Jeremy E. Martin |author2=Martin Gross |year=2011 |title=Taxonomic clarification of ''Diplocynodon'' Pomel, 1847 (Crocodilia) from the Miocene of Styria, Austria |journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen |volume=261 |issue=2 |pages=177–193 |doi=10.1127/0077-7749/2011/0159 }}</ref> Other [[genera]] have recently been found to be [[Synonym (taxonomy)|synonymous]] with ''Diplocynodon''. ''Hispanochampsa muelleri'' of Spain was determined to be synonymous with ''Diplocynodon'' in 2006,<ref name=Hispanochampsa/> and ''Baryphracta deponaie'' of Germany was confirmed to be synonymous with ''Diplocynodon'' in 2012.<ref name=Baryphracta/>

Well preserved specimens have been found in the [[Messel Pit]] and the [[Geiseltal]] [[lignite]] deposit in [[Germany]]. Most articulated ''Diplocynodon'' specimens from these localities contain [[gastroliths]]. In the [[Eocene]] epoch, the German sites were either a swampy freshwater lake (Messel Pit) or a peat bog swamp (Geiseltal). 
{{clear left}}

==Species==
{| class="wikitable sortable" border="1"
|-
! colspan="6" align="center" |'''Species'''
|- 
! Species
! Age
! Location
! Unit
! Notes
! Images
|-
|
''D. darwini''
|
[[Lutetian]]
|
{{Flag|Germany}}
|
[[Messel pit]]
|
All specimens are from [[Messel pit]] of Germany. Synonyms are: ''D. ebertsi'' and ''D. hallense''.
| rowspan="11" |[[File:Diplocynodon darwini 2011-07-09 gasometer 37.jpg|thumb|150px|center|''D. darwini'' from [[Messel pit]], [[Hesse]], [[Germany]], 48 million years old]]
[[File:Skull of a Diplocynodon hantoniensis at the Natural History Museum, London 02.JPG|thumb|150px|center|Skull of ''D. hantoniensis'']]
[[File:Diplocynodon cf rateli.JPG|thumb|150px|center|''Diplocynodon cf. ratelii'']]
|-
| 
''D. deponaie''<ref name=Rossman/><ref name=Baryphracta/>
|
[[Middle Eocene]]
| 
{{Flag|Germany}}
| 
[[Messel pit]]
|
Synonyms are: ''Baryphracta deponaie''.
|-
| 
''D. elavericus''<ref name=D.elavericus>{{cite journal |author=Jeremy E. Martin |year=2010 |title=A new species of ''Diplocynodon'' (Crocodylia, Alligatoroidea) from the Late Eocene of the Massif Central, France, and the evolution of the genus in the climatic context of the Late Palaeogene |journal=Geological Magazine |volume=147 |issue=4 |pages=596–610 |doi=10.1017/S0016756809990161 |bibcode=2010GeoM..147..596M |s2cid=140593139 }}</ref>
|
Middle [[Priabonian]]
| 
{{Flag|France}}
| 
[[Domérat]]
| 
All specimens came from [[Allier]], [[Massif Central]] of France.
|-
| 
''D. gervaisi''
|
Earliest [[Rupelian]]
| 
{{Flag|France}}
|
[[Ronzon, France|Ronzon]]
| 
Synonyms are: ''Saurocainus gervaisi''.
|-
| 
''D. hantoniensis''
|
Early [[Priabonian]]
| 
{{Flag|United Kingdom}}
| 
[[Headon Hill Formation]]
|
All specimens came from [[Hordwell]], southern [[England]]. ''D. cf. hantoniensis'' is known from the [[Oligocene]] of [[Dordogne]], France.
|-
|''D. levantinicum<ref name=":0" />''
|[[Oligocene]] ([[Chattian]])
|{{Flag|Bulgaria}}
|[[Maritsa Formation]]
|
|-
|
''D. kochi''
|
Eocene ([[Priabonian]])
|
{{Flag|Romania}}
|
[[Cluj Limestone Formation]]
|
|-
| 
''D. muelleri''<ref name=Hispanochampsa/>
|
Middle [[Rupelian]]
|
{{flag|Spain}}
|
[[El Talladell]]
|
More than 100 are known, all from [[Lleida Province]], Catalonia. Synonyms are: ''[[Hispanochampsa]] muelleri'', ''D. guerini'' and ''D. marini''.
|-
| 
''D. ratelii''
|
* Middle [[Aquitanian (stage)|Aquitanian]]*
* [[Late Eocene]] to [[Early Miocene]]
| 
{{Flag|France}}
| 
[[Saint-Gérand-le-Puy]]*
| 
''D. ratelii'' is the [[type species]] of ''Diplocynodon''. Most of the specimens came from Allier, Massif Central of France. Synonyms are: ''D. gracile''.
|-
| 
''D. tormis''
|
Late [[Bartonian]]
| 
{{Flag|Spain}}
| 
[[Salamanca]]
| 
|-
| 
''D. ungeri''<ref name=Enneodon/>
|
Middle Miocene
| 
* {{Flag|Austria}}*
* {{Flag|France}}
| 
* [[Pannonian Basin]]*
* [[Paris Basin]]
| 
Synonyms are: ''Enneodon ungeri'', ''D. steineri'', and ''D. styriacus'' (see text).
|-
|}
<small>*Locality and/or horizon of the type specimen.</small>

==Phylogeny==
''Diplocynodon'' is one of the [[basal (phylogenetics)|basal]]-most members of the [[superfamily (zoology)|superfamily]] [[Alligatoroidea]]. ''Diplocynodon's'' placement within Alligatoroidea can be shown in the [[cladogram]] below, based on a 2018 [[tip dating]] study by Lee & Yates that simultaneously used [[morphology (biology)|morphological]], molecular ([[DNA sequencing]]), and [[stratigraphic]] ([[fossil]] age) data.<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]] |volume=285 |issue=1881 |doi=10.1098/rspb.2018.1071 |pmid=30051855 |pmc=6030529 |doi-access=free}}</ref>
{{clade| style=font-size:85%;line-height:85%
|label1='''[[Crocodylia]]'''
|1={{clade
 |label1=[[Alligatoroidea]]
 |1={{clade
  |1=''[[Leidyosuchus]]''{{extinct}}
  |2={{clade
   |label1=Diplocynodontinae{{extinct}}
   |1='''''Diplocynodon'''''{{extinct}}
   |label2=[[Globidonta]]
   |2={{clade
    |1={{clade
     |1=''[[Stangerochampsa]]''{{extinct}}
     |2=''[[Brachychampsa]]''{{extinct}} }}
    |2={{clade
     |1=''[[Navajosuchus]]''{{extinct}}
     |label2=[[Alligatoridae]]
     |2={{clade
      |label1=[[Caimaninae]]
      |1={{clade
       |1={{clade
        |1=''[[Caiman (genus)|Caiman]]'' [[File:Caiman crocodilus llanos white background.JPG|90 px]]
        |2=''[[Melanosuchus]]'' [[File:Melanosuchus niger white background.jpg|120 px]] }}
       |2=''[[Paleosuchus]]'' [[File:Dwarf Caiman white background.jpg|90 px]] }}
      |label2=[[Alligatorinae]]
      |2=''[[Alligator]]'' [[File:Alligator white background.jpg|100 px]] }} }} }} }} }}
 |2={{clade
  |1=extinct [[basal (phylogenetics)|basal]] Crocodilians{{extinct}} (including [[Mekosuchinae]]{{extinct}})
  |label2=[[Longirostres]]
  |2={{clade
   |label1=[[Crocodyloidea]]
   |1={{clade
    |1=extinct [[basal (phylogenetics)|basal]] crocodiles{{extinct}}
    |label2=[[Crocodylidae]]
    |2={{clade
     |1=''[[Crocodylus]]'' [[File:Siamese Crocodile white background.jpg|90 px]]
     |2={{clade
      |1=''[[Mecistops]]'' [[File:Crocodylus cataphractus faux-gavial d'Afrique2 white background.JPG|90 px]]
      |2=''[[Osteolaemus]]'' [[File:Bristol.zoo.westafrican.dwarf.croc.arp. white background.jpg|90 px]] }} }} }}
   |label2=[[Gavialoidea]]
   |2={{clade
    |1=extinct [[basal (phylogenetics)|basal]] Gavialoids{{extinct}}
    |label2=[[Gavialidae]]
    |2={{clade
     |1=''[[Gavialis]]'' [[File:Gavialis gangeticus (Gharial, Gavial) white background.jpg|110 px]]
     |2=''[[Tomistoma]]'' [[File:Tomistoma schlegelii. white background.JPG|90 px]] }} }} }} }} }} }}

Below is a more detailed [[cladogram]] of ''Diplocynodon'':<ref name="Massonne2019">{{cite journal |author1=Tobias Massonne |author2=Davit Vasilyan |author3=Márton Rabi |author4=Madelaine Böhme |year=2019 |title=A new alligatoroid from the Eocene of Vietnam highlights an extinct Asian clade independent from extant ''Alligator sinensis'' |journal=PeerJ |volume=7 |pages=e7562 |doi=10.7717/peerj.7562 |pmid=31720094 |pmc=6839522 |doi-access=free }}</ref>
{{clade| style=font-size:100%;line-height:100%
 |label1=''Diplocynodon'' 
 |1={{clade
  |1=''Diplocynodon deponiae''
  |2=''Diplocynodon darwini''
  |3=''Diplocynodon hantoniensis''
  |4={{clade
   |1=''Diplocynodon ratelii''
   |2={{clade
    |1=''Diplocynodon tormis''
    |2=''Diplocynodon muelleri'' }} }} }} }}

In a 2025 study, Jules D. Walter and colleagues argue that many character states previously thought to be diagnostic for alligatoroids were actually much more widespread. In their analysis several genera traditionally viewed as basal alligatoroids, among them ''Diplocynodon'', were found to not only fall outside of Alligatoroidea but to not even be true crocodilians, instead representing derived non-crocodilian eusuchians.<ref name=W25>{{Cite journal |last1=Walter |first1=J. D. |last2=Massonne |first2=T. |last3=Paiva |first3=A. L. S. |last4=Martin |first4=J. E. |last5=Delfino |first5=M. |last6=Rabi |first6=M. |title=Expanded phylogeny elucidates ''Deinosuchus relationships'', crocodylian osmoregulation and body-size evolution |year=2025 |journal=Communications Biology |volume=8 |at=611 |doi=10.1038/s42003-025-07653-4 |doi-access=free |pmc=12018936 }}</ref>

== Palaeobiology ==
Osteohistological analysis of ''D. hantoniensis'' suggests that it had a similar pattern of growth to the modern [[American alligator]], exhibiting a determinate, seasonally-controlled rate of growth. Additionally, ''D. hantoniensis'' was allometrically very similar to American alligators, with the femoral length and femoral circumference scaling in a similar fashion in both species.<ref>{{Cite journal |last1=Hoffman |first1=D. K. |last2=Goldsmith |first2=E. R. |last3=Houssaye |first3=A. |last4=Maidment |first4=S. C. R. |last5=Felice |first5=R. N. |last6=Mannion |first6=Philip D. |date=9 February 2025 |title=Evolution of growth strategy in alligators and caimans informed by osteohistology of the late Eocene early-diverging alligatoroid crocodylian Diplocynodon hantoniensis |journal=[[Journal of Anatomy]] |language=en |doi=10.1111/joa.14231 |issn=0021-8782 |doi-access=free |pmid=39924872 }}</ref>

[[CT scan|CT scans]] of ''D. tormis'' reconstruct internal structures of its snout and a portion of its brain, with implications for its sensory and cognitive capabilities. The relative sizes of the [[Olfactory bulb|olfactory bulbs]] overlap with alligatoroids and fall short of true crocodiles, adding to anatomical evidence for a closer relationship to alligatoroids. The [[Superior colliculus|optic lobes]] and [[reptile encephalization quotient]] are proportionally smaller than other medium-sized crocodilians, though this could be influenced by incomplete preservation at the back of the skull.<ref>{{Cite journal |last1=Serrano-Martínez |first1=Alejandro |last2=Luján |first2=Àngel H. |last3=García-Pérez |first3=Ángel |last4=Fortuny |first4=Josep |date=2025-02-24 |title=New data on the inner skull cavities of Diplocynodon tormis (Crocodylia, Diplocynodontinae) from the Duero Basin (Iberian Peninsula, Spain) |url=https://fr.pensoft.net/article/133743/ |journal=Fossil Record |language=en |volume=28 |issue=1 |pages=67–77 |doi=10.3897/fr.28.133743 |doi-access=free |issn=2193-0074}}</ref>

== Palaeoecology ==
Based on skull shape analysis of the crocodylians known from the [[Lutetian]] site of Geiseltal, ''Diplocynodon'' was a small generalist carnivore that partitioned its resources with the larger ''[[Asiatosuchus]]''.<ref>{{Cite journal |last1=Hastings |first1=Alexander K. |last2=Hellmund |first2=Meinolf |date=January 2017 |title=Evidence for prey preference partitioning in the middle Eocene high-diversity crocodylian assemblage of the Geiseltal-Fossillagerstätte, Germany utilizing skull shape analysis |url=https://www.cambridge.org/core/journals/geological-magazine/article/abs/evidence-for-prey-preference-partitioning-in-the-middle-eocene-highdiversity-crocodylian-assemblage-of-the-geiseltalfossillagerstatte-germany-utilizing-skull-shape-analysis/717771502180E87AA6FE3E8966955D72 |journal=[[Geological Magazine]] |language=en |volume=154 |issue=1 |pages=119–146 |doi=10.1017/S0016756815001041 |bibcode=2017GeoM..154..119H |issn=0016-7568 |access-date=19 February 2025 |via=Cambridge Core|url-access=subscription }}</ref> According to enamel [[Δ13C|δ<sup>13</sup>C]] values from specimens from the [[Chattian|Late Oligocene]] site of Enspel, the ''Diplocynodon'' living in the palaeoenvironment fed primarily on aquatic vertebrates.<ref>{{Cite journal |last1=Tütken |first1=Thomas |last2=Absolon |first2=Julia |date=12 February 2015 |title=Late Oligocene ambient temperatures reconstructed by stable isotope analysis of terrestrial and aquatic vertebrate fossils of Enspel, Germany |url=https://link.springer.com/article/10.1007/s12549-014-0183-7 |journal=Palaeobiodiversity and Palaeoenvironments |language=en |volume=95 |issue=1 |pages=17–31 |doi=10.1007/s12549-014-0183-7 |bibcode=2015PdPe...95...17T |issn=1867-1594 |access-date=23 December 2024 |via=Springer Nature Link|url-access=subscription }}</ref> 

==References==
{{Reflist}}
* ''Fossils'' (Smithsonian Handbooks) by David Ward (Page 243)

==External links==
{{Portal|Paleontology}}
*[http://www.tlzenterprises.com/Merchant5/merchant.mvc?Screen=PROD&Store_Code=100&Product_Code=REP-700&Category_Code=Reptiles Discover]
*[http://geolmag.geoscienceworld.org/cgi/content/abstract/147/4/596 Geo Science]

{{Extinct Crocodilia|A.}}
{{Taxonbar|from=Q13797209|from2=Q1254623|from3=Q41164376|from4=Q41164378|from5=Q41164384|from6=Q41164387|from7=Q41164391|from8=Q41164396|from9=Q20717785}}

[[Category:Alligatoroidea]]
[[Category:Paleocene crocodylomorphs]]
[[Category:Eocene crocodylomorphs]]
[[Category:Oligocene crocodylomorphs]]
[[Category:Miocene crocodylomorphs]]
[[Category:Miocene genus extinctions]]
[[Category:Paleocene reptiles of Europe]]
[[Category:Paleocene first appearances]]
[[Category:Eocene reptiles of Europe]]
[[Category:Oligocene reptiles of Europe]]
[[Category:Miocene reptiles of Europe]]
[[Category:Prehistoric pseudosuchian genera]]
[[Category:Fossils of Austria]]
[[Category:Fossil taxa described in 1847]]