| Voay | |
|---|---|
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| Skull,American Museum of Natural History | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Archosauromorpha |
| Clade: | Archosauriformes |
| Order: | Crocodilia |
| Family: | Crocodylidae |
| Subfamily: | Crocodylinae |
| Genus: | †Voay Brochu, 2007 |
| Type species | |
| †Voay robustus (Grandidier & Vaillant, 1872) | |
| Synonyms | |
Crocodylus robustusGrandidier & Vaillant, 1872 | |
Voay is anextinctgenus ofcrocodile fromMadagascar that lived during theLate Pleistocene toHolocene, containing only one species,V. robustus. Numeroussubfossils have been found, including complete skulls, noted for their distinctive pair of horns on the posterior, as well as vertebrae andosteoderms from such places asAmbolisatra andAntsirabe. The genus is thought to have become extinct relatively recently. It has been suggested to have disappeared in theextinction event that wiped out much of the endemicmegafauna on Madagascar, such as theelephant bird andMalagasy hippo, following the arrival of humans to Madagascar around 2000 years ago.[2] Its name comes from theMalagasy word for crocodile.
One unusual feature ofV. robustus that distinguishes it from other crocodilians is the presence of prominent "horns" extending from the posterior portion of the skull. They are actually the posterolaterally extended corners of thesquamosal bone. Other related crocodilians such asAldabrachampsus also had similar bony projections, although inAldabrachampsus these projections were more like crests than horns.[3] Another diagnostic characteristic is the near-exclusion of thenasals from the external naris. It had a shorter and deeper snout than the extantCrocodylus niloticus, as well as relatively robust limbs. The osteoderms had tall keels and were dorsally symmetrical with curved lateral margins, running the entire length of the postcranial body.[4]
V. robustus would have measured around 3.5–4 m (11–13 ft) long and weighed about 170 kg (370 lb).[5][6] These estimates suggest thatV. robustus was the largest predator to have existed in Madagascar in recent times. Its size, stature, and presumed behavior is similar to the modernNile crocodile (Crocodylus niloticus). BecauseV. robustus shared so many similarities with the Nile crocodile there must have been a great deal of interspecies competition for resources between the two crocodile genera if they were to have coexisted with one another. It has recently been proposed that the Nile crocodile only migrated to the island from mainlandAfrica afterV. robustus had become extinct in Madagascar.[5] However, this was subsequently disproved after someCrocodylus specimens from Madagascar were found to be at least 7,500 years old and contemporaneous withVoay.[7]
WhenV. robustus was first described in 1872, it was originally assigned to the genusCrocodylus.[8] It was later found to morphologically have had more in common with the extantOsteolaemus, ordwarf crocodile, thanCrocodylus. Some features it shared withOsteolaemus include a depressed pterygoid surface that forms achoanal "neck" on the palate. Because it was not close enough to be placed in the same genus as the dwarf crocodile, it was assigned to the new genus in 2007. Before this reassignment, the species was considered by some to besynonymous withCrocodylus niloticus. However, this was most likely due to a misinterpretation of remains from the livingC. niloticus withV. robustus and the poor description of the original material from which the species was described.[9][10] In contrast to the morphological similarities withOsteolaemus, a 2021 study usingpaleogenomics foundVoay to be a sister group toCrocodylus, with both genera diverging in the mid-lateOligocene; this indicates that the apparent similarities withOsteolaemus are likely due toconvergent evolution.[11]
The belowcladogram shows the results of the latest study:[11]
| Crocodylidae |
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| (crown group) |
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