Voay
Encyclopedia
Voay is an extinct genus
of crocodylid crocodilia
n. Numerous subfossil
s have been found from Madagascar
, including complete skulls as well as vertebrae and osteoderm
s from such places as Ambolisatra and Antsirabe
. The genus is thought to have become extinct relatively recently during the Holocene
. It has even been suggested to have disappeared in the extinction event that wiped out much of the endemic megafauna
such as the elephant bird
following the arrival of humans to Madagascar around 2000 years ago.
Its size, stature, and presumed behavior is similar to the modern Nile Crocodile
(Crocodylus niloticus). Because Voay shared so many similarities with the Nile crocodile there must have been a great deal of interspecific 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 mainland Africa
after Voay had gone extinct in Madagascar.
. Other related crocodilians such as Aldabrachampsus
also had similar bony projections, although in Aldabrachampsus these projections were more like crests than horns. Another diagnostic characteristic is the near-exclusion of the nasals
from the external naris. It had a shorter and deeper snout than the extant Crocodylus 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.
Voay robustus has been estimated to have obtained lengths up to 5 m and a weight of 170 kg. These estimates suggest that V. robustus was the largest predator to have ever existed in Madagascar in recent times.
. However, it is now known to have had more in common with the extant Osteolaemus, or dwarf crocodile
, than Crocodylus. Some features it shares with Osteolaemus include a depressed pterygoid surface that forms a choana
l "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 be synonymous
with Crocodylus niloticus. However, this was most likely due to a misinterpretation of remains from the living C. niloticus with V. robustus and the poor description of the original material from which the species was described.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of crocodylid crocodilia
Crocodilia
Crocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...
n. Numerous subfossil
Subfossil
Subfossil refers to remains whose fossilization process is not complete, either for lack of time or because the conditions in which they were buried were not optimal for fossilization....
s have been found from Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
, including complete skulls as well as vertebrae and osteoderm
Osteoderm
Osteoderms are bony deposits forming scales, plates or other structures in the dermal layers of the skin. Osteoderms are found in many groups of extant and extinct reptiles, including lizards, various groups of dinosaurs , crocodilians, phytosaurs, aetosaurs, placodonts, and hupehsuchians...
s from such places as Ambolisatra and Antsirabe
Antsirabe
Antsirabe is the third largest city in Madagascar and has a population of approximately 183,000. It's the capital of the Vakinankaratra region...
. The genus is thought to have become extinct relatively recently during the Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
. It has even been suggested to have disappeared in the extinction event that wiped out much of the endemic megafauna
Megafauna
In terrestrial zoology, megafauna are "giant", "very large" or "large" animals. The most common thresholds used are or...
such as the elephant bird
Elephant bird
Elephant birds are an extinct family of flightless birds found only on the island of Madagascar and comprising the genera Aepyornis and Mullerornis.-Description:...
following the arrival of humans to Madagascar around 2000 years ago.
Nile crocodile
The Nile crocodile or Common crocodile is an African crocodile which is common in Somalia, Ethiopia, Uganda, Kenya, Egypt, Tanzania, Zambia, Zimbabwe, Gabon, South Africa, Malawi, Sudan, Botswana, and Cameroon...
(Crocodylus niloticus). Because Voay shared so many similarities with the Nile crocodile there must have been a great deal of interspecific 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 mainland Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
after Voay had gone extinct in Madagascar.
Description
One unusual feature of Voay 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 the squamosal boneSquamosal
The squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...
. Other related crocodilians such as Aldabrachampsus
Aldabrachampsus
Aldabrachampsus is an extinct genus of crocodylian. A horned crocodile, its incomplete remains were found on Aldabra Atoll in the western Indian Ocean. It was small and lived during the Pleistocene....
also had similar bony projections, although in Aldabrachampsus these projections were more like crests than horns. Another diagnostic characteristic is the near-exclusion of the nasals
Nasal bone
The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face, and form, by their junction, "the bridge" of the nose.Each has two surfaces and four borders....
from the external naris. It had a shorter and deeper snout than the extant Crocodylus 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.
Voay robustus has been estimated to have obtained lengths up to 5 m and a weight of 170 kg. These estimates suggest that V. robustus was the largest predator to have ever existed in Madagascar in recent times.
Phylogenetics
When Voay robustus was first described in 1872, it was originally assigned to the genus CrocodylusCrocodylus
Crocodylus is one of three genera from the Crocodylinae subfamily extending from the Crocodylidae family.Established species include three extinct species:* † Crocodylus acer - probably represents a distinct genus....
. However, it is now known to have had more in common with the extant Osteolaemus, or dwarf crocodile
Dwarf Crocodile
The dwarf crocodile is an African species of crocodile. It is also the smallest extant crocodile species in the world. Recent sampling has identified three genetically distinct populations...
, than Crocodylus. Some features it shares with Osteolaemus include a depressed pterygoid surface that forms a choana
Choana
Choana is the posterior nasal aperture.The choanae are separated by the vomer.- Boundaries :It is the opening between the nasal cavity and the nasopharynx....
l "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 be synonymous
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
with Crocodylus niloticus. However, this was most likely due to a misinterpretation of remains from the living C. niloticus with V. robustus and the poor description of the original material from which the species was described.