Mekosuchinae

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Cladus: Sarcopterygii
Cladus: Rhipidistia
Cladus: Tetrapodomorpha
Cladus: Eotetrapodiformes
Cladus: Elpistostegalia
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Infraclassis: Archosauromorpha
Cladus: Crurotarsi
Divisio: Archosauria
Subsectio: Pseudosuchia
Cladus: Suchia
Cladus: Paracrocodylomorpha
Cladus: Loricata
Superordo: Crocodylomorpha
Ordo: Crocodilia
Cladus: Mesoeucrocodylia
Cladus: Neosuchia
Subordo: Eusuchia

Familia: Crocodylidae
Subfamilia: †Mekosuchinae
Genera (8): Australosuchus – Baru – Kambara – Mekosuchus – Pallimnarchus – Quinkana – Trilophosuchus – Volia
Name

Mekosuchinae Balouet & Buffetaut, 1987
References

Balouet J.C. & Buffetaut E., 1987. Mekosuchus inexpectatus, ng, n. sp., crocodilien nouveau de l’holocène de Nouvelle Calédonie. Comptes rendus de l'Académie des sciences. Série 2, Mécanique, Physique, Chimie, Sciences de l'univers, Sciences de la Terre. Reference page.

Mekosuchinae is an extinct clade of crocodilians from the Cenozoic of Australasia. They first appear in the fossil record in the Eocene in Australia, and survived until the arrival of humans: in the Pleistocene in Australia and within the Holocene in the Pacific islands of Fiji, New Caledonia and Vanuatu.

Mekosuchine crocodiles are a diverse group. One of the last species, Mekosuchus inexpectatus from Holocene New Caledonia, may have been arboreal.[1] The early Miocene species Harpacochampsa camfieldensis may have resembled a false gharial. Another mekosuchine fossil, currently undescribed, has been found in Miocene deposits from New Zealand. One genus, Mekosuchus, managed to spread to the islands of the Pacific; it is believed to have island-hopped across the Coral Sea, moving first to a now submerged island known as Greater Chesterfield Island, then New Caledonia and onwards. In the Pleistocene, Quinkana was one of the top terrestrial predators of the Australian continent.

Mekosuchines underwent a drastic decline in post-Miocene Australia, with all genera, except for Quinkana and Paludirex (both perishing during the Quaternary extinction event) becoming extinct in Australia by the end of the Pliocene. After the demise of Quinkana and Pallimnarchus, the group survived on Vanuatu and New Caledonia until the arrival of humans, who are presumed to have driven them to extinction.
Phylogeny
Mekosuchus inexpectatus

Mekosuchinae is cladistically defined as a node-based taxon composed of the last common ancestor of Kambara implexidens, Mekosuchus inexpectatus, and all of its descendants.[2]

Mekosuchinae is traditionally thought to be included as a basal member Crocodyloidea,[3] although this is disputed.[4] A 2018 tip dating study by Lee & Yates simultaneously using morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data established the inter-relationships within Crocodilia,[4] which was expanded upon in 2021 by Hekkala et al. using paleogenomics by extracting DNA from the extinct Voay.[5]

The below cladogram shows the results of the latest studies, which placed Mekosuchinae outside of Crocodyloidea, as more basal than Longirostres (the combined group of crocodiles and gavialids).[4]

Crocodylia

Alligatoroidea       Prodiplocynodon†       Asiatosuchus†       "Crocodylus" affinis†       "Crocodylus" depressifrons†         "Crocodylus" acer†     Brachyuranochampsa†       Mekosuchinae   Australosuchus†         Kambara taraina†     Kambara implexidens†         Kambara murgonensis†           Kalthifrons†     ‘Pallimnarchus’†         Baru wickeni†       Baru darrowi†     Baru Alcoota†               Bullock Creek taxon†     Baru huberi†         Volia†       Mekosuchus†       Trilophosuchus†     Quinkana†                   Longirostres Crocodyloidea   "Crocodylus" megarhinus†     Crocodylidae     Gavialoidea   extinct basal Gavialoids†   Gavialidae   Gavialis     Tomistoma

 
 
References

Naish, Darren (13 May 2009). "The small, recently extinct, island-dwelling crocodilians of the south Pacific". Tetrapod Zoology. ScienceBlogs. Retrieved 27 November 2010.
Rio, Jonathan P.; Mannion, Philip D. (6 September 2021). "Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem". PeerJ. 9: e12094. doi:10.7717/peerj.12094. PMC 8428266. PMID 34567843.
Stein, Michael D.; Yates, Adam; Hand, Suzanne J.; Archer, Michael (2017). "Variation in the pelvic and pectoral girdles of Australian Oligo–Miocene mekosuchine crocodiles with implications for locomotion and habitus". PeerJ. 5: e3501. doi:10.7717/peerj.3501. PMC 5494174. PMID 28674657.
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. 285 (1881). doi:10.1098/rspb.2018.1071.

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): 1–11. doi:10.1038/s42003-021-02017-0. ISSN 2399-3642. PMC 8079395.

Mead, J. I.; Steadman, D. W.; Bedford, S. H.; Bell, C. J.; Spriggs, M. (August 2002). Guyer, C. (ed.). "New extinct mekosuchine crocodile from Vanuatu, South Pacific". Copeia. 3 (3): 632–641. doi:10.1643/0045-8511(2002)002[0632:NEMCFV]2.0.CO;2.