Journal of Biogeography
Volume 30 Issue 10 Page 1545 - October 2003
doi:10.1046/j.1365-2699.2003.00929.x

The trans-Pacific zipper effect: disjunct sister taxa and matching geological outlines that link the Pacific margins
Dennis McCarthy*

Abstract

AimTo combine analyses of trans-Pacific sister taxa with geological evidence in order to test the hypothesis of the existence of a Panthalassa superocean.

Location The study is concerned with taxa, both fossil and extant, from East Asia, Australia, New Zealand, South America and North America.

MethodsPhylogenetic and distributional analyses of trans-Pacific biota were integrated with geological evidence from the Pacific and circum-Pacific regions.

ResultsA series of recent biogeographical analyses delineates a zipper-like system of sister areas running up both margins of the Pacific, with each section of western North and South America corresponding to a particular section from East Asia/Australia/New Zealand. These sister areas coincide neatly with a jigsaw-like fit provided by the matching Mesozoic coastlines that bracket the Pacific.

Main conclusionsThe young age (<200 Myr) of oceanic crust, the matching Mesozoic circum-Pacific outlines, and a corresponding system of interlocking biogeographical sister areas provide three independent avenues of support for a closed Pacific in the Upper Triassic-Lower Jurassic. The hypothesis of the existence and subsequent subduction of the pre-Pacific superocean Panthalassa is not only unnecessary, it conflicts with this evidence. Panthalassa-based paleomaps necessitate the invention of dozens of additional hypotheses of species-dependent, trans-oceanic dispersal events, often involving narrow-range taxa of notoriously limited vagility, in order to explain repeated examples of the same biogeographical pattern. Removing the vanished-superocean hypothesis reunites both the matching geological outlines and all the disjunct sister taxa. In brief, what appears to be a multi-era tangle of convoluted, trans-oceanic distributions on Panthalassa-based paleomaps is actually a relatively simple biogeographical pattern that is explainable by a single vicariant event: the opening and expansion of the Pacific.

Of course, the Mars Society duo (Eby and Vancil) don't much care about science -- just about having guys run around in silly low budget spacesuits pretending they are doing something worthwhile about Mars. I guess their comic book subsriptions to Buck Rogers have expired!

BD