Tomistoma

Superregnum: Eukaryota
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Cladus: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Infraclassis: Archosauromorpha
Cladus: Crurotarsi
Divisio: Archosauria
Subdivisio: Pseudosuchia
Superordo: Crocodylomorpha
Ordo: Crocodilia
Subordo: Eusuchia

Familia: Gavialidae
Subfamilia: Tomistominae
Genus: Tomistoma
Species: T. schlegelii – †T. taiwanicus – †T. tandoni
Name

Tomistoma Müller, 1846
References

S. Müller: Ueber den Character der Thierwelt auf den Inseln des indischen Archipels, ein Beitrag zur zoologischen Geographie. Archiv für Naturgeschichte 12(1): 109–128. (1846)

Vernacular names
English: False Gharial
latviešu: Gaviālkrokodili
ไทย: ตะโขง

Tomistoma is a genus of gavialid crocodylians. They are noted for their long narrow snouts used to catch fish, similar to the gharial. Tomistoma contains one extant (living) member, the False gharial (Tomistoma schlegelii), as well as potentially several extinct species: T. cairense, T. lusitanicum, T. taiwanicus, T. coppensi, and T. dowsoni. However, these species may need to be reclassified to different genera as studies have shown them to be paraphyletic.[2][3]

Unlike the gharial, the false gharial's snout broadens considerably towards the base and so is more similar to those of true crocodiles than the gharial, whose osteology indicated a distinct lineage from all other living crocodilians.[4] However, although more morphologically similar to Crocodylidae based on skeletal features, recent molecular studies using DNA sequencing consistently indicate that the false gharial and by inference other related extinct forms traditionally viewed as belonging to the crocodylian subfamily Tomistominae actually belong to Gavialoidea and Gavialidae.[5][6][7][8][9][10][2][11]
Fossil dorsal plates of "Tomistoma" calaritanus

Fossils of extinct Tomistoma species have been found in deposits of Paleogene, Neogene, and Quaternary ages in Taiwan, Uganda, Italy, Portugal, Egypt and India, but nearly all of them are likely to be distinct genera due to older age compared to the false gharial.[12]

The below cladogram of the major living crocodile groups is based on molecular studies and shows the false gharial's close relationships:[6][9][10][2][11]

Crocodilia

Alligatoridae Caimaninae     Caiman     Melanosuchus       Paleosuchus     Alligatorinae Alligator     Longirostres Crocodylidae   Crocodylus       Mecistops     Osteolaemus       Gavialidae   Gavialis     Tomistoma

 
 

Here is a more detailed cladogram from a 2018 tip dating study by Lee & Yates simultaneously using morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data that shows the false gharial's proposed placement within Gavialidae, including extinct members:[2]

Gavialoidea

Gavialidae                 Gavialis gangeticus Gharial     Gavialis bengawanicus†       Gavialis browni†       Gryposuchus colombianus†       Ikanogavialis†         Gryposuchus pachakamue†     Piscogavialis†         Harpacochampsa†           Toyotamaphimeia†     Penghusuchus†       Gavialosuchus†           Tomistoma lusitanica†     Tomistoma schlegelii False gharial     (crown group)   Tomistoma cairense†       Dollosuchoides†         Maroccosuchus†     Paratomistoma†         Kentisuchus†

(stem-based group)

References

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.
Lee, M. S. Y.; Yates, A. M. (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. PMC 6030529. PMID 30051855.
Iijima, M.; Momohara, A.; Kobayashi, Y.; Hayashi, S.; Ikeda, T.; Taruno, H.; Watanabe, K.; Tanimoto, M.; Furui, S. (2018). "Toyotamaphimeia cf. machikanensis (Crocodylia, Tomistominae) from the Middle Pleistocene of Osaka, Japan, and crocodylian survivorship through the Pliocene-Pleistocene climatic oscillations". Palaeogeography, Palaeoclimatology, Palaeoecology. 496: 346–360. Bibcode:2018PPP...496..346I. doi:10.1016/j.palaeo.2018.02.002.
Piras, P., Colangelo, P., Adams, D. C., Buscalioni, A., Cubo, J., Kotsakis, T., & Raia, P. (2010). The Gavialis–Tomistoma debate: the contribution of skull ontogenetic allometry and growth trajectories to the study of crocodylian relationships. Evolution & development, 12(6): 568−579.
Densmore, L. D.; Owen, R. D. (1989). "Molecular Systematics of the Order Crocodilia". American Zoologist. 29 (3): 831–841. doi:10.1093/icb/29.3.831.
Harshman, J.; Huddleston, C. J.; Bollback, J. P.; Parsons, T. J.; Braun, M. J. (2003). "True and false gharials: A nuclear gene phylogeny of crocodylia". Systematic Biology. 52 (3): 386–402. doi:10.1080/10635150309323. PMID 12775527.
Gatesy, J.; Amato, G.; Norell, M.; DeSalle, R.; H. C. (2003). "Combined support for wholesale taxic atavism in gavialine crocodylians". Systematic Biology. 52 (3): 403–422. doi:10.1080/10635150309329. PMID 12775528.
Willis, R. E.; McAliley, L. R.; Neeley, E. D.; Densmore Ld, L. D. (2007). "Evidence for placing the false gharial (Tomistoma schlegelii) into the family Gavialidae: Inferences from nuclear gene sequences". Molecular Phylogenetics and Evolution. 43 (3): 787–794. doi:10.1016/j.ympev.2007.02.005. PMID 17433721.
Gatesy, J.; Amato, G. (2008). "The rapid accumulation of consistent molecular support for intergeneric crocodylian relationships". Molecular Phylogenetics and Evolution. 48 (3): 1232–1237. doi:10.1016/j.ympev.2008.02.009. PMID 18372192.
Erickson, G. M.; Gignac, P. M.; Steppan, S. J.; Lappin, A. K.; Vliet, K. A.; Brueggen, J. A.; Inouye, B. D.; Kledzik, D. & Webb, G. J. W. (2012). "Insights into the ecology and evolutionary success of crocodilians revealed through bite-force and tooth-pressure experimentation". PLOS ONE. 7 (3): e31781. Bibcode:2012PLoSO...731781E. doi:10.1371/journal.pone.0031781. PMC 3303775. PMID 22431965.
Hekkala, E.; Gatesy, J.; Narechania, A.; Meredith, R.; Russello, M.; Aardema, M. L.; Jensen, E.; Montanari, S.; Brochu, C.; Norell, M.; Amato, G. (2021). "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. PMC 8079395. PMID 33907305.
"Fossilworks: Tomistoma". fossilworks.org.