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VERTEBRATE PALEONTOLOGY OF ISLA DE MONA, PUERTO RICO
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Short Description: Copyright Š 1998 by Edward F. Frank and Richard Benson. Journal of Cave and Karst Studies, August 1998 • 103. Edward F. Frank and Richard Benson-Vertebrate ...
Content Inside: Edward F. Frank and Richard Benson-Vertebrate Paleontology of Isla de Mona, Puerto Rico. Journal of Cave and Karst Studies 60(2): 103-106.
VERTEBRATE PALEONTOLOGY OF ISLA DE MONA, PUERTO RICO
EDWARD F. FRANK AND RICHARD BENSON
University of Minnesota, Department of Geology and Geophysics, and Bell Museum of Natural History, Minneapolis, MN 55455 USA
Vertebrate fossil materials were collected from over a dozen cave localities on Isla de Mona, Puerto Rico. Guano deposits at these localities were excavated and sifted to recover bone materials. The predominant vertebrate fossils recovered at every sifting site were Audubon's shearwater (Puffinus lherminieri) bones. Fragmentary undifferentiated lizard bones were also found sporadically in the sifted material. Fossil skeletal bones and fresh bones from other bird species were found on the surface of the cave floors at several localities. Extensive fossil guano deposits on the island are interpreted to be of mixed origin with deposits near entrances primarily derived from bird guano, and deposits from the darker interiors of the caves derived from bat guano.
Isla de Mona is a small, isolated island located in the Mona Passage, 68 km west of Puerto Rico and 60 km east of Hispaniola. There are a limited number of native, non-flying, vertebrate species extant on Isla de Mona. These include nine species of terrestrial reptiles (six lizards and three snakes), one species of amphibian (coqui tree frog), and two species of native mammals, both bats (Wiewandt 1973). Five species of sea turtle live in the Caribbean region. Hawksbill, leatherback, and green turtles nest on Isla de Mona and the others may nest there occasionally, as well. Mammals on the island presently include rats, mice, goats, pigs, and wild house cats, and in the recent past have also included dogs, burros, and cattle. All non-native species were brought to the island by settlers, miners, and pirates (Weiwandt 1973). Remains of a large rodent (Isolobodon potoricensi) were reported from the island by Anthony (1926) and later workers, but always in association with Taino archaeological sites. These rodents were a common item in the diet of the Taino Indians and could easily be carried by them from one island to another (Weiwandt 1973). Rafaele (1973) provides a list of 97 species of birds that have been observed on the island, but only 14 have significant breeding populations. Similar patterns of endemicism and cross-island affinities are apparent in the vegetation on the island (Woodbury 1973) and terrestrial arthropods (Velez 1973; Martorell 1973; Peck & Kuklova-Peck 1981). The particular terrestrial species represented and the limited diversity, or departerate nature are characteristic of island populations established by waif dispersal as described most recently by Stehli and Webb (1985) and Perfit and Williams (1989). In waif dispersal, animasl are carried to oceanic islands primarily by clinging to floating debris that has been washed out to sea or carried by flying birds or bats to the island. PALEONTOLOGICAL INVESTIGATIONS There have been few investigations of Isla de Mona verte-
brate paleontology. The earliest work of note was by H.W. Anthony in 1926 (Anthony 1926, Goodwin 1926). Anthony was interested in finding mammal bones on that expedition, but met with little success. He found isolated fragments of Isolobodon sp., but all were associated with Taino sites. Fragments of unidentified bird bones were found in indurated crevice fill material. Fish bones were in a phosphate bed within extensive guano deposits. He attributed the origin of this deposit as altered guano from a fish-eating bat (Noctilio lepornus mastivus). The most significant discovery was tortoise bones from two localities on the eastern side of the island. The first was from an unidentified crevice fill, the second was a more complete skeleton from the Cathedral Chamber in Cueva del Lirio at Punta Este. The material from the later skeleton (Geochelone (Monachelys) monesis) was first described by Williams (1952), revised by Auffenberg (1967). The reconstructed skull was 6 cm long, suggesting a shell size of ~0.5 m. Geochelone is the only genus yet found in the fossil record in the Caribbean. Geochelone specimens have been found in Cuba, Sombrero Island, New Providence Island, Navassa, Curacao, and Antigua (Auffenberg 1967; Pregill 1991). Kaye (1959) described a deposit of bones from the Audubon's Shearwater (Puffinus lherminieri) intermingled with charcoal in the back of Cueva Negra on the southwestern side of the island. He hypothesized the remains to be a midden refuse deposit from paleo-Indian feasts. Recent radiocarbon dating of the associated charcoal remains yielded a conventional radiocarbon age of 380 + 60, or a corrected nominal calendar age of 1525 AD, with a one deviation range of 1480 to 1655 AD (Frank 1998a). This age is consistent with Kaye's interpretation. This represents the period encompassing the contact between Taino populations and Europeans. Circumstantial evidence suggests that this deposit was a Taino midden, but a European origin can not be completely ruled out. None of the other samples collected in 1995 were associated with Taino archaeological materials and may be substantially older.
Copyright 1998 by Edward F. Frank and Richard Benson
Journal of Cave and Karst Studies, August 1998 103
