RE: Insects at K/T boundary

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From: 	N. MacLeod[SMTP:N.MacLeod@nhm.ac.uk]
Sent: 	Thursday, June 26, 1997 8:25 PM
To: 	Multiple recipients of list
Subject: 	Re: Insects at K/T boundary

Neale's point was perfectly valid. In order to demonstrate the hibernation
hypothesis one would need to show that those Cretaceous insect groups that
hibernate, or that hibernate in particular ways preferentially survived.
The idea that insects as a whole survived whatever environmental changes
took place as a result of a K-T impact because certain modern groups
hibernate is an assumption (some would say a rationalization), not a true
explanation.

Three other observations.

>All life was not wiped out--some groups
>preferentially survived.

At the level of the taxonomic Class (e.g., Class Insecta) all organismal
groups survived the K-T boundary.

>If you think not much happened, compare what was walking around on
>land in late Cretaceous communities with what was present in early
>Paleocene communities on land.

If modern patterns are any indication, most of what was "walking around" in
Cretaceous and Paleocene terrestrial habitats was of the insect persuasion.
It looks like we've established that Cretaceous plant floras and insect
faunas were not substantially affected by their movement through the late
Maastrichtian extinction event. That, in itself, accounts for most of the
terrestrial biomass (at least the part of which that would leave a fossil
record).

Finally, most of the snapshots of Cretaceous and Paleocene terrestrial
landscapes preserved in the fossil record only tell us that a change took
place over this interval. Not the pace, or cause of that change across any
particular horizon. Most likely multiple causes were involved. See Dave
Jablonski's recent review of the K-T biotic story (Nature 387:354-355) and
the papers he cites therein for the most current summary.

Norm MacLeod



>On Thu, 26 Jun 1997, Neale Monks wrote:
>
>> Heinz & Andy Ross wrote:-
>>
>> >>Hibernation seems the most plausible reason why insects were hardly
>>affected
>> >>by the K/T boundary event.
>>
>> Or perhaps there wasn't much to affect them?
>>
>> Neale.
>>
>
>I suggest reading Conrad Labandeira's work a little more closely, especially
>the paper in Science (1993) v. 261:310-315.  The insect mouthpart study
>form the 92 NACP abstract will be in the next Annual Review of Ecology
>and Systematics.  I think insects are one of the groups that were buffed
>from the effects of the impact.  All life was not wiped out--some groups
>preferentially survived.
>
>Neal-- If you think not much happened, compare what was walking around on
>land in late Cretaceous communities with what was present in early
>Paleocene communities on land.




___________________________________________________________________

Dr. Norman MacLeod
Micropalaeontological Research
N.MacLeod@nhm.ac.uk (E-mail)

Department of Palaeontology, The Natural History Museum,
Cromwell Road, London, SW7 5BD

Office Phone: 0171-938-9006
Dept. FAX: 0171-938-9277
E-mail: N.MacLeod@nhm.ac.uk
___________________________________________________________________
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