dxb105@csc.anu.oz (David Bofinger, Theoretical Physics, RSPhysS ANU) (10/10/89)
I'm cross-posting this to sci.bio, partly to get this line of the conversation out of sci.space, and partly in the hope an expert can help out. In article <5661@portia.Stanford.EDU>, joe@hanauma.stanford.edu (Joe Dellinger) writes: > Well, I would tend to agree with you, but there are precedents to > the contrary. South America is a much larger continent than North > America, I suppose in biomass terms this is probably true. > so you would expect it to be able to "hold its own" > evolutionarily against invaders... and yet when the isthmus of Panama > formed (quite recently geologically speaking) the North American mammals > almost _immediately_ spread South and _totally wiped out_ all the native > South American mammals. I think the point was that South America was isolated. North America had a (tenuous) link to the _real_ powerhouse of terrestrial evolution- Afro-Eurasia. It wasn't North American mammals that colonised South America: it was Asian ones, via the Bering strait. ______________________________________________________________________________ David Bofinger ACSNet: dxb105@phys0.anu.oz [@munnari.oz.au] (Australia) Snail: Dept. of Theoretical Physics, RSPhysS, ANU, ACT, 2601 Annex space now. Canada wants us to, and Tom Neff can't stop us.