Oryzomys antillarum

Unraveling the Mystery of Oryzomys antillarum: Jamaica’s Vanished Rodent

Imagine a world where a small rodent roamed freely, its reddish fur blending with the forest floor, and its yellow underbelly glowing like a beacon in the dark. This was Oryzomys antillarum, an extinct species that once called Jamaica home. But what exactly does this tell us about the natural history of our planet? Let’s dive into the fascinating tale of this vanished creature.

From Discovery to Debate: The Classification Conundrum

Was Oryzomys antillarum a distinct species or just a weakly differentiated subspecies? This question has puzzled scientists for decades. First formally described in 1898, based on a specimen collected since 1845, the classification of this rodent has been a subject of much debate. Clayton Ray and Philip Hershkovitz both concluded that it was a ‘weakly differentiated subspecies’ of Oryzomys palustris. However, in 1993, Gary Morgan reinstated Oryzomys antillarum as a distinct species.

The Genus Oryzomys: A Family of Rodents

According to Carleton and Arroyo-Cabrales, Oryzomys is a genus that spans from eastern North America to northwestern South America. Goldman compared USNM specimens to Oryzomys couesi, noting the skulls and teeth were similar but with distinct differences. The USNM specimens were more reddish, while their skull features differed, including smaller interparietal bones and less developed nasal and cheekbones.

Physical Characteristics: A Semiaquatic Rodent

Oryzomys antillarum had a reddish upperpart and yellowish underpart, with a tail about as long as the head and body. It was semiaquatic and closely associated with water, which may have influenced its occurrence on the island. Three modern cave specimens showed varying measurements for skull length, palate width, incisive foramina length, and upper molar crown length.

Historical Records: A Vanished Species

The oldest well-dated record of Oryzomys antillarum is at Drum Cave, dated to between 10,250 and 11,260 years before present. Historical records are scarce but suggest that the species declined rapidly following European colonization of Jamaica. Gosse collected a British Museum specimen in 1845, while USNM specimens were received after he wrote his monograph; their origin is disputed among authors (1874-1877).

Extinction: A Tragic Tale

No specimens have been collected since, and the species is listed as extinct on the IUCN Red List. Its extinction is attributed to the introduction of the Indian mongoose in 1872, Rattus species, and environmental changes after British takeover in 1655. The brown rat possibly being the cause of its demise, it’s a stark reminder of how human activities can have devastating effects on wildlife.

As we reflect on the story of Oryzomys antillarum, it serves as a poignant reminder of the delicate balance in nature and the impact of human actions. The extinction of this species is not just a loss to science but a warning about our responsibility towards the environment. What lessons can we learn from its disappearance? How can we ensure that future generations do not face similar tragedies?