[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Novel invasion of dino-haven by K/T mammals.

Several people have critisized this analogy: mammals are to threatened 
island species (eg., NZ), as mammals were to Cretaceous dinosaurs.  The 
general feeling among them is that dinosaurs, since they were exposed to 
the mammmals' tactics over the Mesozoic, should have been able to respond 
to it with adaptations of their own.  In the past I have attacked this 
view by claiming structural constraints of the eggs, and of the dinosaurs 
(eg., inability to burrow) limited the range of possible evolutionary 
responses.  I still hold this view.  But now I want to tackle the 
complaints head on.
Even if the dinosaurs had the genetic wherewithal to develop arrropriate
anti-mammal/bird "technologies", they had no time to do so.This was because 
they were essentially ISOLATED from the mammals!  What I mean is,  with 
reference to the _direction_ of predation, dinosaurs had had no 
contact with the mammals.  All of the predation had gone the other way, 
i.e., dinosaurs were preying on mammmals.  Suffering intense predation, 
mammals evolved technologies of stealth, technologies which had _nothing_ 
to do with preying on dinosaurs.  Rather, they were devoted to keeping 
the mammals alive!  But, in one of the greatest examples of evolutionary 
_karma_, these same technologies of defence, also became technologies of  
_offence_.  When it did, the dinosaurs, adaptationally speaking, were 
caught off guard.  They had never been exposed to threats of such a novel 
nature: burrowing ability, cognitive powers, aural, visual acuity and so 
When we talk about speciation from ancestral stocks, we refer to 
allopatric and sympatric speciation.  With regard to these topics, 
islands can refer, really, to the tops of mountains (inasmuch as the 
ancestral stocks never come into contact with each other), or any barrier 
to gene flow.  With reference, now to exposure to mammal->dinosaur 
predation, the two species were isolated.  The small animal niche, and 
the open-field big dinosaur niche were functional islands.  In this 
sense, just as we have observed them do in NZ, Hawaii, Galapagos, they 
walked into the habitat of a new species and exploited them with their 
stealth-driven adaptations.