PALEOBIOGEOGRAPHY OF THE MARINE REALM 183 



Meanwhile available evidence for the Devonian seems at least as 

 well explained by mechanisms that do not demand the former 

 existence of a cratonic link or links as by those that do (see also 

 Gill, 1958, p. 115). 



But what of other evidence for Gondwana? The late Paleozoic 

 Glossopteris-Gangamopteris flora, which Gondwana was invented 

 to explain in the first place (Teichert, 1958, p. 563), has lost ground 

 as proof of continental linkage with the discovery of associated 

 winged sporelike bodies in the Permian of India, i\ustralia, 

 Antarctica, and perhaps South Africa (Virkki, 1937; Sahni, 1938, 

 pp. 14-15, 20-21). Simpson (1953, pp. 61-62) concluded, "All the 

 biogeographic features in the known history of mammals are best 

 accounted for on the theory that the continents have had their 

 present identities and positions." The fresh water galaxid fishes of 

 southern South America, Africa, Australia, and New Zealand are 

 widely euryhaline, and Myers (1949) suggested that they could 

 probably cross the present ocean basins. Teichert (1958) finds 

 present paleobiogeographic evidence to indicate the existence of 

 open ocean west of Australia since early Paleozoic and isolation of 

 Australia since Permian or earlier. 



Gondwana as a transoceanic land mass, therefore, remains an 

 as yet unsatisfactorily documented and biogeographically unnec- 

 essary hypothesis. Insofar as its biogeographic basis is concerned, 

 the linking elements could just as well have been dispersed from 

 an ice-free Antarctic center under the influence of the circum- 

 Antarctic West Wind Drift or the wind itself, aided by the north- 

 ward deflection resulting from Coriolis force; or, in the case of the 

 terrestrial vertebrates, through demonstrable northern hemisphere 

 routes. 



The Gondwana glaciers are another problem (see King, 1958, 

 for a recent viewpoint). If there were large waxing and waning ice 

 masses anywhere during the right parts of the late Paleozoic, they 

 might help to explain the extensive cyclothemic sedimentation of 

 these times, repeating a regular succession of small rises and falls 

 of the sea (or the land). However, as suggested earlier, the evidence 

 for all supposed examples of pre-Pleistocene glaciation needs 

 review in the field. 



