The term “horned crocodile” most commonly refers to Voay robustus, an extinct crocodile species that once roamed Madagascar. While some modern crocodilians exhibit bony protrusions on their skulls, Voay robustus is specifically recognized for the distinct, prominent “horns” on the back of its head.
Distinctive Physical Features
Voay robustus possessed prominent bony “horns” or crests on the posterior part of its skull, specifically extended corners of the squamosal bone, which gave it its common name. These distinctive features set it apart from other crocodilians.
Voay robustus was a robust animal, measuring around 3.5 to 5 meters (11 to 16 feet) in length and weighing approximately 170 kilograms (370 pounds). Its snout was shorter and deeper than the modern Nile crocodile, and it had strong limbs. Bony plates, or osteoderms, with tall keels extended along its entire body.
Ancient Habitat and Behavior
Voay robustus was endemic to Madagascar, living from the Late Pleistocene into the Holocene period. Its size and presumed behavior were similar to the modern Nile crocodile, suggesting it occupied a comparable ecological niche. It inhabited various aquatic ecosystems across the island, such as rivers, lakes, and wetlands, where it was a dominant predator.
As the largest predator in Madagascar in recent times, Voay robustus would have preyed upon other ancient Madagascan animals. This included the island’s unique megafauna, such as giant tortoises, elephant birds, dwarf hippos, and various lemur species, many of which also became extinct around the same period. Its robust skull suggests it was a powerful predator, capable of taking down substantial prey.
Unearthing Its Past and Disappearance
The first discoveries of Voay robustus remains occurred in 1872 when Alfred Grandidier and Vaillant initially described it as Crocodylus robustus. Numerous subfossil remains, including complete skulls, vertebrae, and osteoderms, have been unearthed from locations such as Ambolisatra and Antsirabe in Madagascar. These findings were important in understanding its morphology and evolutionary history.
For many years, the classification of Voay robustus was debated, with some researchers initially considering it an ancestor of Nile crocodiles. However, in 2007, analysis of fossil skulls revealed significant physiological differences, leading to its reclassification into a new genus, Voay, a Malagasy word for “crocodile”. Further studies, including the recovery of partial mitochondrial genomes from 1,300 to 1,400-year-old specimens, placed Voay robustus as a sister lineage to true crocodiles (Crocodylus), suggesting an African origin for the common ancestor of modern crocodiles.
Voay robustus existed until relatively recently, with fossil evidence indicating its presence as recently as 1,300 to 1,400 years ago. The arrival of modern humans in Madagascar, between 9,000 and 2,500 years ago, coincided with the extinction of much of the island’s large vertebrates, including Voay robustus. Theories suggest that human activities, such as hunting and habitat alteration, combined with environmental changes, played a significant role in its disappearance.