Inevitable simultaneous extinction?

[KELL00BELL@aol.com]

          The extinction of the dinosaurs (for whatever reason) could have 
triggered the demise of mosasaurus and other thermophilac sea life.  The 
immediate aftermath of dinosaur extinction probably witnessed a major 
increase in terrestrial plant biomass in the absence of megaherbivores to 
suppress it.  An increase in vegetation could have caused a reduction in 
atmospheris CO2, absorbed by plants, a reduced greenhouse effect, and cooler 
temperatures which, coupled with regression, could have dealt the coup de 
grace to thermophilac marine reptiles.
     Since the Triassic, dinosaurs were probably the key element in a warmer 
Gaian regime they "invented" and maintained.  Suppressing vegetation with 
their appetites, dinosaurs kept CO2 levels and global temperatures high, 
which facilitated recuperative growth (especially after angiosperms appeared) 
and thus maximized the productivity of the land, supporting huge dinosaurian 
sizes and populations, even with elevated metabolic rates.
     If this view is correct, the existence of dinosaurs was essential to the 
maintenance of Mesozoic warmth.  Sea reptiles were beneficiaries of 
dinosaurian dominance and could not survive without them.
     A very important point is that the near-simultaneous extinction of 
dinosaurs and sea reptiles need not imply a common agency of extinction.  The 
dinosaur extinction may have caused marine extinctions indirectly, made them 
inevitable.  Generally, it is assumed that the lack of a common biological 
agency of extinction, on land and at sea, implies a common physical agency 
e.g. an asteroid.  But a biological agency or agencies could have 
extinguished the dinosaurs AND, indirectly, the sea creatures, for the latter 
may have needed the dinos.
     --Tim Donovan