Voay

Name: Voay.
Phonetic: Vo-ay.
Named By: C.‭ ‬A.‭ ‬Brochu‭ ‬-‭ ‬2007.
Synonyms: Crocodylus robustus.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Crocodylidae,‭ ‬Crocodylinae.
Species: V.‭ ‬robustus‭ (‬type‭)‬.
Diet: Carnivore.
Size: Estimated up to‭ ‬5‭ ‬meters long.
Known locations: Madagascar.
Time period: Holocene.
Fossil representation: Skulls,‭ ‬vertebrae,‭ ‬osteoderms.

       The remains of the crocodile Voay were first described as a species of Crocodylus‭ (‬C.‭ ‬robustus‭) ‬back in‭ ‬1872‭ ‬by Grandidier and Vaillant,‭ ‬however later study found that the remains were nearer to the dwarf crocodile Osteolaemus,‭ ‬although not close enough to be included with this genus either.‭ ‬For this reason C.‭ ‬A.‭ ‬Brochu created a new genus under the name Voay in‭ ‬2007,‭ ‬and in keeping with standard practices for naming new genera and species from existing classified material,‭ ‬the species name of robustus was retained to create a new type species of Voay robustus.
       The remains of Voay which include skulls,‭ ‬vertebrae and osteoderms‭ (‬the bony armour plates in the skin that are also sometimes called‭ ‘‬scutes‭’) ‬are classed as sub fossils which mean that they have not been completely fossilised.‭ ‬These remains are also dated to as recently as two thousand years ago,‭ ‬something that suggests that the genus went extinct with the arrival of the first humans upon Madagascar.‭ ‬This also coincides with the disappearance of other large animals from Madagascar at this time which has led to theory that human hunting may have been a factor in‭ ‬the‭ ‬disappearance of these animals.‭ ‬Although Voay is dated during the Holocene,‭ ‬a disappearance two thousand years ago would on paper suggest that the genus only lived ten thousand years.‭ ‬Realistically however,‭ ‬Voay probably also existed into the at least the late Pleistocene era,‭ ‬but further fossil remains from different time periods would be needed to establish and confirm a more complete temporal range for this genus.
       The Nile crocodile‭ (‬Crocodylus niloticus‭) ‬is also known from Madagascar,‭ ‬but there is some debate concerning‭ ‬whether the Nile crocodile and Voay co-existed in Madagascar at the same time,‭ ‬or if Nile crocodiles colonised Madagascar to fill a predatory void left behind by the disappearance of Voay.‭ ‬At this point either theory is plausible since although similarly sized,‭ ‬Voay is morphologically different to the C.‭ ‬niloticus.‭ ‬One key area is the more robust limbs,‭ ‬and since crocodiles usually rely upon their tails for swimming,‭ ‬the stronger limbs might suggest that Voay spent a greater amount of time on the land than C.‭ ‬niloticus.‭ ‬This could also mean a stronger disposition towards hunting and possibly even scavenging on land,‭ ‬which would infer different specialisation and behaviour to the C.‭ ‬niloticus.
       Voay also has a proportionately shorter and deeper snout than C.‭ ‬niloticus with nasal openings that are also reduced in size.‭ ‬This also infers a different prey specialisation to the longer and more slender snouted C.‭ ‬niloticus and if the two lived in the same habitats,‭ ‬it’s possible that they may have been able to coexist by adopting different lifestyles.‭ ‬A precedent could be established by looking at South American crocodiles of the Miocene.‭ ‬Here you had three giant crocodiles called Purussaurus,‭ ‬Gryposuchus and Mourasuchus.‭ ‬All three lived in the same approximate geographic area but each specialised in a different feeding strategy.‭ ‬Purussaurus had a skull similar to a caiman,‭ ‬indicating that it was a hunter of large prey.‭ ‬Gryposuchus however was more like a gharial‭ (‬alternatively gavial‭) ‬and was suited to hunting fish.‭ ‬Finally Mourasuchus seems to have been a filter feeder that consumed large amounts of small prey animals.‭ ‬Even though we still don’t know exactly how well these three crocodiles got on,‭ ‬it is possible that they could inhabit the same water systems without‭ ‬competing for the same food as one another.
       Voay did have a pair of horns that grew from the back of its head that were actually extensions of the squamosal bone‭ (‬one of the most rearward portions of the skull‭)‬.‭ ‬These horns are often seen in other crocodiles as well,‭ ‬which has led to the more common term of these species and genera being called‭ ‘‬horned crocodiles‭’‬.

Further reading
- Description of a skull of the extinct Madagascar crocodile, Crocodilus robustus Vaillant and Grandidier. - Bulletin of the American Museum of Natural History 44 (4): 25. - Charles C. Mook.
- The giant dwarf crocodile: a reappraisal of ‘Crocodylus’ robustus from the Quaternary of Madagascar. In: Patterson, Goodman & Sedlock, eds., Environmental Change in Madagascar. p. 70. - C. A. Brochu & G. W. Storrs - 1995.
- Morphology, relationships, and biogeographical significance of an extinct horned crocodile (Crocodylia, Crocodylidae) from the Quaternary of Madagascar. - Zoological Journal of the Linnean Society 150:835-863. - C. A. Brochu - 2007.
- The late Pleistocene horned crocodile Voay robustus (Grandidier & Vaillant, 1872) from Madagascar in the Museum f�r Naturkunde Berlin. - Fossil Record 12: 13. - C. Bicklemann, N. Klein - 2009.

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