LOST MAMMALS OF HISPANIOLA

Extinct Giant Antillean Sloths

       Ground sloths of the family Megalonychidae inhabited the islands of Hispaniola and Cuba as far back as the Pleistocene, which extends back to about 2.5 million years ago. Two sub-families, Choloepodinae and Megalonchinae, occupied these islands. Most of the species are now extinct.  They varied tremendously in appearance and size - weighing as much as a living South American sloths, 9kg/20lbs, and up to 90kg/200lbs! 

     

        The subfamily Megalonchinae, which is now entirely extinct, included the largest of the Antillean sloths, Megalocnus (“The Great Sloth” 90kg/200lbs), Parocnus (“The Greater Haitian Ground Sloth” 70kg; 154lbs) and Acratocnus (22-68kg/48-150lbs). Because of their great body size, some of these animals must have foraged on the ground. Neocnus was the exception among the giant sloths of its time. A member of the subfamily Choloepodinae, Neocnus was the smallest of the Antillean sloths, weighing approximately 9kg/20lbs. It would have resembled the living two-toed sloth, Choloepus, only slightly smaller and with a longer tail. Like its cousins, it was a folivore, but Neocnus spent more time in the trees and was well adapted to climbing with its large claws.

 

       The remains of Neocnus have been found in dry caves in the Hispaniolan mountains as well as the underwater caves in the lowlands near Bayahibe, which indicates an ecologically flexible lifestyle.  

These animals lived into the modern era, when they were likely driven to extinction by the early human inhabitants of these islands. Some reports written by early European visitors suggest that Megalocnus survived in the Greater Antilles until the 15th-16th century, not long after the Spanish first occupied the region. 

 

Further Reading:

Iturralde-Vinent MA, MacPhee RDE. 1999. Paleogeography of the Caribbean Region: Implications for the Cenozoic Biogeography. Bulletin American Museum of Natural History 238:1–95.

 

MacPhee R. 2005. “First” appearances in the Cenozoic land‐mammal record of the Greater Antilles: significance and comparison with South American and Antarctic records. Journal of Biogeography 32:551–564.

 

Steadman DW, Martin PS, MacPhee RDE, Jull AJT, McDonald HG, Woods CA, Iturralde-Vinent MA, Hodgins GWL. 2005. Asynchronous extinction of late Quaternary sloths on continents and islands. Proceedings of the National Academy of Sciences of the United States of America 102:11763–11768.

The Disappearing Rodents of Hispaniola 

The “Plate-Toothed Giant Hutia.” Elasmodontomys, is a large extinct rodent native to the Antilles, but possibly related to a South American ancestor known from Argentine fossils.  Its remains come primarily from underwater caves. We do not know when Elasmodontomys died out, but they probably persisted for some time after the first human colonists of the islands arrived.  As a large rodent weighing up to 13kg/29lbs, it is not hard to imagine humans hunting them down for food. 

       

       Plagiodontia is another rodent found in the Antilles. Plagiodontia means "oblique-tooth," a name that refers to the slanted angle of cutting edges seen on the chewing surface of the rodent's teeth. Species from this genus are either extinct or endangered. The endangered species of Hispaniola were found in deep caves on the mountain of Miragoare, in Haiti. Their presence in deep caves gives us a better understanding of why we might find the fossils of the extinct species in underwater caves – they may have sheltered or foraged for insects in the caves when the sea levels were lower and the caves were dry.

 

       Living Plagiodontia tend to be nocturnal climbers. Their fingers are arrayed as four clawed digits paired with a thumb that has a short blunt nail, which makes the hand suited for grasping.  Weighing less than 0.5kg/1lb, predation by humans is probably not the pressure that is driving them to extinction. Instead, its declining populations may be suffering from competitor species introduced by humans, namely the black rat, Rattus rattus.

 

Further Reading:

Hansford J, Nuñez-Miño JM, Young RP, Brace S, Brocca JL, Turvey ST. 2012. Taxonomy-testing and the “Goldilocks Hypothesis”: morphometric analysis of species diversity in living and extinct Hispaniolan hutias. Systematics and Biodiversity 10:491–507.

 

Morgan GS, Woods CA. 1986. Extinction and the zoogeography of West Indian land mammals. Biological Journal of the Linnean Society 28:167–203.

Bats of Hispaniola

       There are seven families of bats living on Hispaniola today -  18 living species that vary greatly in size and diet. The largest is Noctilio leporinus, also known as “the greater bulldog bat.” It has a wingspan of up to 1m/3ft! They are sexually dimorphic, which means that males are larger than females. They weigh 50-90 grams and are found predominantly in tropical lowland forests in and around caves. One of the smallest Hispaniolan bats is Chilonalatus micropus, weighing only 2-3 grams. These insect-eaters, visually striking due to large funnel-shaped ears, are also found on mainland South America, and prefer deep caves with abundant moisture. 

 

       Because it preserves an abundance of bat fossils, one of the caves investigated by the DRSS team is now called “Oleg’s Bat House.” Today the cave is flooded, but it provides a record of a once vibrant scene when the water level was lower. The bones of crocodiles and snakes that probably fed on the bats were also found there.  And we found two unexpected bat species, Pteronotus macleayii, a species that today lives in Cuba and Jamaica, and the extinct Cuban bat Mormoops magna.  Before their discovery in Oleg’s Bat House, no one knew that these species had ever lived on Hispaniola. 

 

Further Reading:

Fenton MB, Simmons NB. 2015. Bats: A World of Science and Mystery. Chicago: University of Chicago Press.

 

Velazco PM, O'Neill H, Gunnell GF, Cooke SB, Rímoli RO, Rosenberger AL, Simmons NB. 2013. Quaternary bat diversity in the Dominican Republic. American Museum Novitates:1–20.

 
 

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