Prodromus of Vertebrate Paleontology of Bermuda

Bermuda is an isolated oceanic island situated 1000 km ESE of Cape Hatteras, North Carolina (Fig. 1, inset). Its volcanic core, last active during the Oligocene (Reynolds & Aumento, 1974), was probably subaerial for some of its existence because rare basaltic pebbles and a small percentage of volcanic grains have been found in surface deposits. Apart from the initial volcanic origin of Bermuda, the most important factor affecting the geology of the island has been fluctuating sea-levels during the Pleistocene, with marine carbonate deposition on the platform during interglacial high sea stands. An excellent summary of the Quaternary history of Bermuda may be found in Vacher et al. (1995). The exposed rocks on the island consist almost entirely of biogenic carbonate dunes or “eolianite” (a term coined by Sayles, 1931) formed from comminuted mollusk shells, coral, coralline algae, and foraminifera. These sediments are transported to the shore by waves and currents, and are subsequently blown onto land by strong winds. The eolianites form primarily during interglacial highstands when rises in sea-level flood the Bermuda platform (Bretz, 1960; Land et al., 1967), and during early regression from the highstand position. Thus, eolianites are landward facies of shoreline deposits. During glacial periods of sufficient intensity to bring sea-level below the edge of the platform, the shelf is exposed and biogenic sediment formation ceases because the highest parts of the platform (present-day Bermuda islands) are essentially cut off from eolianite deposition. During glacial lowstands, red soils develop from oxidation of the underlying limestone and deposition of wind-borne dust coming off of the Sahara Desert (Glaccum & Prospero, 1980; Muhs et al., 1990). These soils redden with age, and become heavily leached while exposed to the elements over tens or hundreds of thousands of years. Thus, they seldom contain identifiable fossils. However, in caves and fissures fossils are protec-