90 H. A. ARMSTRONG & A. W. OWEN
Fig. 4. (a)Constrained sedation matrices for the Baltica shelf for each of the time slices described in the text.
Source of locality data for Estonia from Sweet & Bergstrom (1984); Sweden from Bergstrom (1990): Poland
from Dzik (1994); Oslo from Smith (1999). Balto-Scandian locations are constrained onshore to offshore from
the confacies belts proposed by Jaanusson (1976). (b) Biofacies architecture diagrams; note the intermediate
position of OB3 in the velicuspis Chron data.
euconodont biofacies. They defined biofacies three confacies belts in the Middle Ordovician of
based upon cluster analysis assuming a priori the Appalachians, based upon shelly faunas and
that all euconodonts were pelagic. Their euconodonts. Their inshore Lee and Tazewell
approach clusters localities based on included belts contain almost identical euconodont faunas
euconodonts, grouping both pelagic and nekto- including Belodella, Belodina, Appalachig-
benthic taxa. Constrained seriation enables the nathus, Curtognathus, Erismodus, Phragmodus
separation of pelagic and nektobenthic taxa and and Plectodina. This fauna contains a mixture of
our reinterpretation of only North Atlantic OB1 (coniform) and SB2 (non-coniform) taxa.
Province and coniform taxa as pelagic makes The offshore Blount Belt contains the eucono-
direct comparison with this work difficult. For donts of OB2, plus Protopanderodus (previously
example SB2 includes genera common with the Cordylodus) and 'Polyplacognathiis'. They also
Aphelognathus-Oulodus and Plectodina Bio- noted the similarity at species level of their
facies of Sweet & Bergstrom (1984), SB3 has Blount Belt fauna with Baltoscandian faunas of
elements in common with the Phragmodus- the same age and the horizontal uniformity of
Icriodella-Plectodina Biofacies though is not a this fauna across various confacies belts. Both of
direct correlative. OB2 has genera in common these observations support our contention that
with the Hamarodus-Dapsilodus-Scabbardella these taxa were pelagic.
(HDS) Biofacies and OB3 has taxa in common Stouge & Rasmussen (1996) identified the
with the Amorphognathus Biofacies, but neither HDS Biofacies in the lower Ashgill of Bornholm
is directly comparable. and concluded that widespread geographical
Jaanusson & Bergstrom (1980) recognized distribution indicated that this faunal assemblage
