Tomistoma

Tomistoma Temporal range: Eocene - Recent, 47.8–0 Ma[1] PreꞒ Ꞓ O S D C P T J K Pg N
False gharial (Tomistoma schlegelii)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauromorpha
Clade:	Archosauriformes
Order:	Crocodilia
Family:	Gavialidae
Subfamily:	Tomistominae
Genus:	Tomistoma S. Müller, 1846
Species
Tomistoma schlegelii †Tomistoma cairense †Tomistoma coppensi †Tomistoma dowsoni †Tomistoma lusitanicum

Tomistoma is a genus of gavialid crocodilians. 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. coppensi, and T. dowsoni. However, these species may need to be reclassified to different genera as studies have shown them to be paraphyletic, for example: previously assigned species T. taiwanicus from Taiwan, is reclassified to the genus Toyotamaphimeia, and T. dowsoni should be excluded from Tomistoma based on phylogenetic analysis.^{[2][3][4][5][6]}

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.^[7] 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.^{[8][9][10][11][12][13][2][14]}

Fossils of extinct Tomistoma species have been found in deposits of Paleogene, Neogene, and Quaternary ages in 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.^[15]

The below cladogram of the major living crocodile groups is based on molecular studies and shows the false gharial's close relationships:^{[9][12][13][2][14]}

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]

References

This page was last edited on 23 February 2024, at 12:10