A bone bed in the Eocene of Jamaica

Abstract

Pre-pleistocene fossil vertebrates are rare fossils in the Antillean region. The majority of vertebrate deposits found in the West Indies are of Late Pleistocene age, usually, but not always (MacPhee et al., 1989), dating from after the last interglacial. These faunas are cave and fissure accumulations of disarticulated bones of small terrestrial vertebrates, particularly rodents, birds, and lizards. In contrast, pre-Quaternary vertebrates of the Caribbean islands are particularly poorly known. For example, Jamaica, which has one of the most extensively studied fossil records in the region, has hitherto produced only three Tertiary vertebrates, all aquatic and hitherto known only from unique specimens. These include: the late Early Eocene sirenian Prorastomus sirenoides Owen, 1855, originally described on the basis of the skull, mandible, and atlas vertebra (for a recent discussion of this species, see Savage, 1977); the lower jaw of the early Middle Eocene crocodilian Charactosuchus kugleri Berg, 1969; and a fragment of needlefish jaw from the Pliocene (Caldwell, 1966). It is therefore significant to report the discovery of an early Middle Eocene sequence in which bones are not uncommon, including a bone bed that has produced a moderate diversity of aquatic (marine?) taxa.

Jamaican Tertiary marine Vertebrata

“…The locality is the same as the type locality of the crocodylian Charactosuchus kugleri (see above), but the sirenian came from a slightly higher bed than the latter (Donovan et al, 1990). A detailed description of the new Prorastomus material, together with a redescription of the holotype, is being prepared by R.J.G.…”

“…Like modern manatees, it probably fed on freshwater aquatic plants in rivers and on seagrasses in nearshore marine and estuarine waters. The depositional environment of the Dump Limestone Lenticle was possibly a brackish lagoon (Donovan et al, 1990).…”

“…The beds exposed at this locality form the type section of the Dump Limestone Lenticle, Guys Hill Sandstone Member, Chapelton Formation, and are of basal middle Eocene age (Robinson, 1969). The crocodylian fossils are from a poorly cemented, muddy limestone (bed 3 of Donovan et al, 1990 , Fig. 2).…”

“…Recent collecting efforts at the Charactosuchus kugleri type locality have located several isolated crocodylian bones (Donovan et al, 1990). These include a tooth, an isolated osteoderm (bony scute), and a phalanx, all probably representing one individual (USNM 437770).…”

Jamaican Cenozoic ichnology: review and prospectus

“…Trace fossils of the Eocene Yellow Limestone Group of western central Jamaica (afterDonovan et al, 1990a;Donovan and Blissett, 1998; Donovan and Portell, in press). Key: B = macroboring; C = coprolites; S = soft-sediment structure BEntobia isp.…”