Tiers of Time and Trials of Extrapolationism 1317
of life's history with a very different form (perhaps entirely devoid of any meaningful
vector of progress) than the extrapolationist premise of Darwinian central logic had
assumed.
Thus, the influence of the "different rules" model in helping to explain the
waxing and waning of taxa in macroevolution represents the most interesting and far-
reaching modification of Darwinian expectations unleashed by catastrophism's
renewed respectability, and by the resulting inadequacy of uniformitarian
extrapolation from Darwinian microevolution to supply a full explanation for the
causes of pattern in life's history. After all, and in admitted caricature, if the size of
dinosaurs had marked their success over mammals in habitats of large terrestrial
vertebrates for more than 130 million years; and if this established basis for
Darwinian success then became an important causal factor in their differential death,
with small size as an equally vital reason for mammalian survival; then the tables
truly turned with the institution of these particular different rules of a K-T moment—
as marks of failure (or at least of limitation) in the long background of Darwinian
competition became fortuitous substrates for survival, while the primary features of
former and such prolonged domination became unalterable portents of doom
(whether directly or, more probably, via such correlated consequences as generally
smaller population sizes and generally greater ecological specialization). "How are
the mighty fallen" exclaimed David in his famous lament (2 Samuel: l). But Goliath
had died by David's superior wit (and good aim), whereas Saul expired as a
consequence of his own madness. Dinosaurs, on the other hand, may have fallen by
their might, but surely not by their fault.
Thus, for these good reasons, the paleontological literature on the biological
implications of mass extinction has, for the past 20 years, rightly focused upon the
documentation of "different rules" in such potentially catastrophic episodes, and on
their impact upon pattern in the history of life. I cannot, in the context of this chapter,
present a compendium of these ever increasing, and ever more sophisticated, studies.
I shall therefore cite just a few of the early results that have already become classic in
a burgeoning field. I should also at least acknowledge—to open up a real can of
worms that I shall not even attempt to close—that, at least partly as a "back
formation" from doubts inspired by the debate on mass extinction, the entire subject
of the efficacy of competition, in normal times as well as in geological perspective,
has fallen under increasing question (see Simberloff, 1983,1984 for some explicitly
microevolutionary doubts; Gould and Calloway, 1980, for a paleontological example;
Benton, 1996, for a general argument from the fossil record; but also Sepkoski, 1996,
for a strong and more nuanced defense of competition in paleontologically normal
times, and Sepkoski et al., 2000, for a beautifully documented and fascinating
example, and Gould, 2000b, for commentary thereupon).
Jablonski published the most important early work on this subject, establishing a
methodology and terminology in his classic paper (Jablonski, 1986b) on
"Background and mass extinctions: the alternation of macroevolutionary regimes."