Diplocynodon is an extinct genus of alligatoroid crocodilian that lived during the Paleocene to Middle Miocene in Europe. Some species may have reached lengths of 3m (10feet),[1] while others probably did not exceed 1m (03feet).[2] They are almost exclusively found in freshwater environments.[3] The various species are thought to have been opportunistic aquatic predators.[4]
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 synonymized with E. ungeri in 2011, and because the name Diplocynodon has priority over Enneodon, the species is now called D. ungeri.[5] Other genera have recently been found to be synonymous with Diplocynodon. Hispanochampsa muelleri of Spain was determined to be synonymous with Diplocynodon in 2006, and Baryphracta deponaie of Germany was confirmed to be synonymous with Diplocynodon in 2012.
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).
| Species | |||||
|---|---|---|---|---|---|
| Species | Age | Location | Unit | Notes | Images |
| D. dalpiazi | Late Rupelian | Monteviale | |||
| D. darwini | Lutetian | Messel pit | All specimens are from Messel pit of Germany. Synonyms are: D. ebertsi and D. hallense. | ||
| D. deponaie | Middle Eocene | Messel pit | Synonyms are: Baryphracta deponaie. | ||
| D. elavericus[6] | Middle Priabonian | Domérat | All specimens came from Allier, Massif Central of France. | ||
| D. gervaisi | Earliest Rupelian | Ronzon | Synonyms are: Saurocainus gervaisi. | ||
| D. hantoniensis | Early Priabonian | Headon Hill Formation | All specimens came from Hordwell, southern England. D. cf. hantoniensis is known from the Oligocene of Dordogne, France. | ||
| D. levantinicum | Oligocene (Chattian) | Maritsa Formation | |||
| D. kochi | Eocene (Priabonian) | Cluj Limestone Formation | |||
| D. muelleri | Middle Rupelian |  Spain | El Talladell | More than 100 are known, all from Lleida Province, Catalonia. Synonyms are: Hispanochampsa muelleri, D. guerini and D. marini. | |
| D. ratelii |
| 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 | Salamanca | |||
| D. ungeri | Middle Miocene |
| Synonyms are: Enneodon ungeri, D. steineri, and D. styriacus (see text). | ||
Diplocynodon is one of the basal-most members of the 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 morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data.[7]
Below is a more detailed cladogram of Diplocynodon:[8]