Portal de Periódicos da CAPES

Devonian palaeontological data and the Armorica problem

1987; Elsevier BV; Volume: 60; Linguagem: Inglês

10.1016/0031-0182(87)90036-8

1872-616X

Gavin C. Young,

Geological and Geophysical Studies

Various palaeogeographic ideas about the relation between Gondwana and Euramerica during the Devonian Period are formalised into four competing hypotheses involving three areas (Euramerica, Gondwana, Armorica) separated by two marine faunal barriers. Palaeontological evidence from Devonian vertebrates is summarised to show support for the hypothesis that Gondwana and Euramerica were contiguous by the Middle Devonian, and that the intervening ocean had been occluded by the Late Devonian. Palaeontological data provide no support for the existence of a wide Devonian ocean separating Euramerica from Gondwana, nor for a discrete continental block (“Armorica”) which may have traversed this ocean during the Devonian. The Armorican region of southern Europe was apparently part of Gondwana during the Early Devonian. Biostratigraphic evidence of discrepancies in the first appearance of various invertebrate taxa between southern Europe, north Africa and North America are consistent with a biotic dispersal model involving shallow marine invertebrates and vertebrates during the early Middle Devonian, and continental faunas and floras in the Late Devonian. The latter event may have occurred at or near the Frasnian-Famennian boundary.