Re: possible role of echolocation in K-T survival

["Matthew Troutman" <m_troutman@hotmail.com>]

>Given that only small terrestrial animals survived the K-T
>event, and given that, among terrestrial animals, SKAIK only the small
>ones echolocate, has there been any attempt to link ability to
>echolocate with survival at the K-T?  (Not that I can suggest any
>means of testing such an idea, even approximately--it just seems
>intuitively likely that something that could help an animal locate
>food and others of its own kind, even in conditions of total darkness,
>might be a significant contributor to survival in some of the proposed
>K-T scenarios.  Especially since it may be a primitive character for
>mammals--perhaps fossilized auditory bullae could give some evidence?)

     That certainly is a unique hypothesis. However, this cannot be a 
factor for all survivors through the K-T. No birds that I know of    
(besides the oilbird?) echolate. As a matter of fact few animals do 
echolate the way you seem to be advocating besides bats and whales and a 
few insects. Most mammals are nocturnal or crespular  and they do not 
echolate. A good example of a nocturnal animal is the phalangeroid 
marsupial,_ Petaurus breviceps_ ( the sugar glider.) This is a 
dermopteran-like marsupial that is nocturnal of can land on branches and 
catch bugs in mid-air. It, however, depends on its eyesight for seeing 
in the dark. From what is gathered, echolation is not a primitive 
characteristic for the Mammalia since no fossil mammalian brains from 
the Mesozoic support echolation. The use of echolation by whales is not 
primitive, it has been shown that there is  a progression toward this 
from their mesonychid ancestors to modern whales as presented by 
Gingerich. We cannot see any progression in bats like this because the 
fossil record is poor in this area.  

MattTroutman

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