It appears that the rigid, en echelon shields formed by jointed arm branches are an adaptation to strengthening the crown and gathering food in highly variable, strong currents in a shallow reef or bioherm
We prefer to use the term bioherm
to describe these features as they are considered to be composed of trapped sediments and both living and dead bivalves, while others (Paull et al.
is a rock formed by accretions from sedentary organisms and surrounded by other kinds of rocks.
The best exposed bioherm
is a biodetrital mound located in a road cut on Highway 157 in Lawrence County, Alabama (Site H157, latitude 30[degrees] 24' 38" N, longitude 87[degrees] 49' 51" W; Fig.
describe ultrastructural features of porostromate microproblematica from a Mulde Event (Homerian) bioherm
in Podolia, Western Ukraine, and Vendrasco and Checa illustrate shell microstructure and its inheritance in the calcitic helcionellid Mackinnonia.
The outcrop is exposed in a narrow vertical trench and the geometry of the bioherm
is not entirely visible.
6) Finally, at the middle Oxfordian, early Transversarium Chronozone the whole platform was homogeneized again and underwent a slow, uniform subsidence, favouring the recovery of subtidal conditions and development of sponge limestone bioherm
and biostrome facies.
faunal assemblage indicates maximum water depths of 20-30 m (Brunton & Copper 1994) consistent with our interpretation.
A number of robust, partly ornamented agglutinated and calcareous benthic foraminifers live in very shallow water of the inner ramp (10 to 50 m waterdepth), on lime sands, near bioherms
and in inter-bioherm
Fossils from the Ordovician bioherm
at Meiklejohn Peak, Nevada.
1982): Cryptalgal-metazoan bioherms
of early Ordovician age in the St.
1999): Facies character and stratal responses to accommodation in Pennsylvanian bioherms
, western Orogrande basin, New Mexico.