After 150 Years, Mysterious Extinction of Horned Crocodiles Finally Solved!

Scientists have now solved the puzzle concerning the extinct horned crocodile, determining precisely where this enigmatic croc belongs on the tree of life after nearly 150 years of debate.

Studying Ancient Remains

According to fossil evidence, the extinct horned crocodiles (Voay robustus) were native to Madagascar as far back as 9,000 years ago and survived as recently as 1,300 to 1,400 years ago. The beasts were first discovered in 1872 and are known for their prominent horns on their skulls. They've been included in several distinct families, misidentified as other animals, and assigned various names since their discovery, with no apparent evolutionary history.

Researchers from the American Museum of Natural History (AMNH) in New York City used DNA analysis to shed light on these enigmatic reptiles and decide if they belong to their own distinct group, according to the news article.

Lead author Evon Hekkala, an AMNH associate at Fordham University in New York, told Live Science, "The DNA tells a different story." "It repeatedly warns us that looks can be deceiving."

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Madagascar Crocodiles

The island nation of Madagascar is now home to invasive Nile crocodiles (Crocodylus niloticus). While the first record of Nile crocodiles in Madagascar dates back 300 years, Hekkala believes that they might have arrived much earlier and coexisted with horned crocodiles.

Hekkala explained that horned crocodiles were not especially massive crocodiles, but their heavyset skulls indicated that they were definitely 'robust,' which contributed to the species name robustus. "We don't have any full skeletons," Hekkala said, "but they weren't particularly long." "Based on the dimensions of their skulls, they were probably around the same size as Nile crocodiles in terms of average size."

According to an AMNH statement, a host of other larger species, including giant tortoises, elephant birds, dwarf hippos, and some lemurs, went extinct on the island at the same time as horned crocodiles. Still, it's uncertain what caused their extinction.

Because of Madagascar's poor fossil record and incomplete ecological history took nearly 150 years to effectively put horned crocodiles in their own evolutionary community. Furthermore, crocodile species are visually similar, especially in their skulls, which scientists have used to distinguish them in the past. However, there can be many differences in skulls, even among members of the same genus, making them look like they're from a different species.

"The shape of a crocodile's head differs significantly depending on age, sex, and even diet," Hekkala said. "A huge, old crocodile skull, for example, may seem to be very distinctive."

Misconception

When the horned crocodiles were first discovered, scientists classified them as true crocodiles. This subfamily includes Nile crocodiles and other modern-day crocodiles such as the American crocodile (Crocodylus acutus) and saltwater crocodile (Crocodylus porosus).

According to Hekkala, the misunderstanding was exacerbated in 1910 when a common image of a horned crocodile would have looked like was published in a science journal. While the illustration represented a modern-day Nile crocodile, it contributed to the myth that the horned crocodiles were real crocodiles. Some also speculated that horned crocodiles were an ancestor of Nile crocodiles.

New Species

This was the general consensus until 2007 when researchers compared the skulls of horned crocodiles to those of Nile crocodiles and discovered significant physiological differences. Following this discovery, horned crocodiles were classified as dwarf crocodiles, smaller crocodiles with short, stout skulls that diverged from true crocodiles millions of years ago. The horned crocodiles were also assigned a new genus name, Voay, Malagasy for "crocodile."

The horned crocodiles were not dwarf crocodiles, as the 2007 report had indicated, nor were they real crocodiles, as earlier naturalists had thought. Instead, they are classified as a separate genus.

This new species, which is closely related to true crocodiles, is only found in Africa, which means that this is where crocodiles first originated, according to the leading hypothesis in the field. "Our findings support the theory that today's crocodiles evolved in Africa," Hekkala said.

Getting to the bottom of the evolutionary mystery surrounding horned crocodiles is critical because it allows scientists to better understand how modern-day animals evolved and how they could respond to transition, according to Hekkala.

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