PALEOBIOGEOGRAPHY

Faunal links for several different groups at generic, and in some instances specific level, have long been known between West Antarctica/South America and New Zealand during Jurassic time (e.g., Stevens 1963, 1967, 1980, 1989; Willey 1973; Quilty 1978, 1983; Thomson 1981; Mutterlose 1986; Crame 1987; Doyle and Howlett 1989; Damborenea and Mancenido 1992). Challinor (1991b) proposed a South Pacific faunal province based on belemnites, extending from southern South America eastwards along the coast of Gondwana as far as New Zealand, and possibly New Caledonia, during Jurassic time. This South Pacific belemnite faunal province is more extensive in time, but approximately co-extensive in geography, with the eastern part of the late Bajocian to early Callovian East Pacific ammonite realm of Westermann (1981), (now subrealm, Westermann and Hudson 1991), that extended from Arctic Canada along the Pacific coasts of North and South America and West Antarctica as far as New Zealand. This study refines and extends knowledge of belemnite occurrences and relationships within the Jurassic of the South Pacific belemnite province.

The distribution of some Latady Group belemnites suggests they migrated from Madagascar to the Antarctic Peninsula. Migration directly southwest from Madagascar via the Trans-Erythraean Seaway (Figure 8 and Lamare 1936; Arkell 1956; the Gondic Corridor of Krishna 1994 and Gardner and Campbell 2002a, 2002b) would have been the shortest and most direct route. A major transgression occurred in the Callovian (Haq et al. 1987, Haq et al. 1988), and when combined with continental rifting in western Gondwana during the early Middle Jurassic (e.g., Grunow 1993a, 1993b; Studinger and Miller 1999), would have formed a short-lived shallow seaway that acted as a migratory pathway. Recent geophysical investigation suggests that the first oceanic crust formed between Africa and Antarctica around 155 Ma (Jokat et al. 2003). The Trans-Erythraean Seaway acted as a conduit for faunal exchange twice during the Middle Jurassic (Bajocian and Callovian) (Krishna 1994; Gardner and Campbell 2002a, 2002b), before becoming fully established as the Indian Ocean in the Tithonian (Hallam 1983). A number of bivalve taxa, rarer crinoids and a coral also migrated to Ellsworth Land from the north via the Trans-Ethryaean Seaway (Gardner and Campbell 2002a, 2002b; Eagle and Hikuroa 2003; Hikuroa 2005).

We are confident that the correlations proposed, both in the taxa present and in the timing of biostratigraphic events, indicate migration between West Antarctica/Argentina and New Zealand (and possibly New Caledonia). The concept of a Middle and Late Jurassic South Pacific belemnite province extending eastwards along the southern margin of Gondwana from southern South America through West Antarctica to New Zealand (Challinor 1991b) remains valid. But the new data presented in this paper indicate that trans-Gondwana migrations introduced Tethyan elements to the fauna of southern South America and West Antarctica during the Middle and Late Jurassic.