The reason I have taken so long to respond is that I've tried to look back
at what I did nearly 25 years ago and also see what the present arguments
are concerning the origin of insects. What I have found would seem to
indicate that I have fallen into the trap I have inadverdently accused
others of i.e speaking outside my competence. The essay I did all
those years back was not actually on the origin of insects but actually
on the origin or arthropods. The question was and still seems to be the
case: 'Did arthropodisation take place once only or more than once?" For
some workers the Insects & Myriapods can be considered quite a
distinct group from the Crustaceans and Trilobites. (See later to see that
this has not sill been resolved.) Similar questions could also be asked
about the actual origin of the Insects. Are the Apterygotes a distinct
grouping from the rest of the insect orders?
As far as the fossil record is concerned, it would seem that the first
distinctive fossil insect is Rhyniella from the Middle Devonian. Though
this described in one publication as 'primitive' ('Fossil Invertebrates' U.
Liehmann and G. Hillmer, Cambridge University Press 1983), another
describes it as belonging to the Collembola - 'a somewhat specialized
evolutionary side-branch.' ('Imm's Outlines of Entomology' 6th Edition,
O. W. Richards & R.G.Davies, Chapman and Hall, 1978) The fact
that it is specialized would indicate that there should be precursors
fromearlier geological time that have not been fossilised or not
discovered. As it is an Apterygote and that Pterygote insects are not
started to be found until Upper Carboniferous, it could lead one to the
conclusion that that Apterygotes should be considered seperately from the
Pterygotes.
Before leaving Rhyniella, Romer ('Procession of Life',
Weidenfield and Nicolson,1968) and several other writers mention its
existence but in 'Biology of Insects', (David J. Horn, W. B. Saunders
1978) there is no mention of it in the chapeter on evolution and the
first fossils are said to be Pterygotes from the Carboniferous. In a
later chapter, the Collembola are described as 'six-legged noninsect
arthropods', which 'may be a very old group, reportedly having been
found in Devonian fossils.' (It is also interesting to note that
in some introductory texts on fossil invertebrates, insects only get
a few lines or none at all compared to page after page on
trilobites.)
As a penultimate paragraph I will make mention of a letter to Nature:
'Evolutionary Origin of insect wings from ancestral gills' (13/2/97,
p627) The authors - Michalis Averof & Stephen M. Cohen - come to the
conclusion that the wings did develop from gills and 'have been built
on genetic functions that were already present in the structural
progenitors of insect wings.' They suggest that 'insect wings
eveolved from gill-like appendages that were already present in in the
aquatic ancestors of both crustceans and insects.' In a caption to a
figure (4) they state: 'The relationships between crustaceans, myriapods
and insects remain controversial and are therefore presented as an
unresolved trichotomy.' One of the things that this suggests to me is
that some cureent thinkers might see a closer relationship between
crustaceans and insects than earliar workers(see above).
If you are still with me, perhaps my ramblings help show the point I
was trying to mistake and at my own expense. The publications that
I have been able to consult don't enable me to get a clear picture or give
an authoritative answer. Hopefully, there is someone out there who can
and help raise the profile of those of us who do believe that there is
more to the workings of the world than revealed by naturalistic
assumptions. Sorry if I have offended any one and many thanks for the
scientific and spiritual stimulation I get from the postings.
Yours in Christ,
Geoff Bagley