Researchers have identified two previously unknown crocodile species living on isolated Caribbean islands — and both are already facing the threat of extinction, a new study reveals.
Until now, these reptiles were believed to be part of the American crocodile species (Crocodylus acutus), which is found across a wide range extending from southern Florida to northern South America. However, scientists discovered that populations inhabiting the island of Cozumel and the atoll of Banco Chinchorro, both off Mexico’s Yucatán Peninsula, are genetically distinct. Each island is home to only about 500 individuals.
The discovery was made as part of a broad study investigating the genetics of crocodiles along Mexico’s Pacific coast, Central America, and the Caribbean. Researchers found significant genetic differences between the Cozumel and Banco Chinchorro populations and the rest of Crocodylus acutus, concluding that the island crocodiles represent two entirely separate, as-yet-unnamed species.
“These results were totally unexpected,” said lead study author José Avila-Cervantes, who conducted the research during his graduate studies at McGill University in Canada. “We assumed Crocodylus acutus was a single species ranging from Baja California to Venezuela and across the Caribbean,” he said in a statement issued by the university.
The findings will be formally published in the June issue of the journal Molecular Phylogenetics and Evolution, though they were first made available online on March 28.
American crocodiles are found in 18 countries, and their range overlaps with other crocodilian species such as the Cuban crocodile (C. rhombifer) in Cuba and Morelet’s crocodile (C. moreletii) in Mexico, Guatemala, and Belize. The researchers initially set out to study variations among these species when they stumbled upon the distinctiveness of the Cozumel and Banco Chinchorro populations.
To reach their conclusion, the team captured and released wild crocodiles to collect blood and tissue samples for DNA analysis. They also incorporated genetic data from previous studies and examined physical differences, particularly in skull shape and size. One key finding was that Banco Chinchorro crocodiles possess a longer and broader snout compared to their counterparts on Cozumel Island.
Beyond the scientific excitement, the discovery has important conservation implications. Crocodile populations across the region are already under pressure from human activities such as urbanization, pollution, and expanding tourism. Although the Cozumel and Banco Chinchorro populations currently appear stable, their small size and limited geographic range make them especially vulnerable to habitat loss and other threats.
“Now that we recognize these crocodiles as distinct species, it’s crucial to protect their habitats,” said Hans Larsson, a biology professor at McGill University and the study’s principal investigator. “Limiting land development and implementing careful conservation strategies on Cozumel and Banco Chinchorro will be key to ensuring their survival.”
The researchers hope that by formally recognizing these crocodiles as separate species, conservationists and policymakers will act swiftly to prioritize their protection, ensuring that these newly discovered creatures continue to thrive in their unique island environments.