Re: environment/inarticulates (posted for M. Sutton)

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From: MARK SUTTON <SGLMDS@cardiff.ac.uk>
To: paleonet-owner@nhm.ac.uk
Date:          Thu, 23 Nov 1995 09:08:11 GMT
Subject:       Re: environment/inarticulates
Priority: normal


> Hi everybody!
> I am working on trilobites from the Tremadoc-Arenig interval in Norway. Here
> it seems to be a hiatus cutting out the Megistaspis armata zone. In the beds
> just above this hiatus there is very few trilobites, but a lot of
> inarticulate brachiopods (Acrotreta, obolus and lingula). Is there anybody
> who have suggestions on what kind of depositional environment this is an
> indicator of (if any)?.
>
Well, I work on British Inarticulate brachiopods from the same range.
As far as I know, no one is at all sure what environment such an
assemblage would indicate. Acrotretid palaeoecology is still
pretty much a closed book. As for 'Obolus' and 'Lingula' (and I would
be very surprised if you actually have either of these genera),
little more information exists. The main thing I can advise is not to
assume that an elongate lingulid was a burrower! You may be better
off looking at degree of disruption of fossils (i.e. the degree to
which dorsal and ventral valves occur together) as an environmental
handle.
Check out Popov and Holmer (1994) for a full taxonomic treatment of
your material. They don't have much information on palaeoenvironment
(in fact, I don't think they have any), but its a start!
There are many speculations on lingulate palaeocecology in the
literature. I would be inclined to treat most if not all of them as
exactly that - speculation!

Sorry to be so negative.


Mark Sutton