Bryozoans as substratum of fossil fistulose Foraminifera (Fam. Polymorphinidae)

Abstract

Ehrhard 198504 15: Bryozoans as substratum of fossil fistulose Foraminifera (Fam. Polymorphinidae). Lethaia, Vol. 18, pp. 155-165. Oslo. ISSN 0024-1164.In the Upper Cretaceous-Lower Tertiary sections exposed in the Curfs quarries at Berg (munic. Berg en Terblijtalso known as Geulhem, southern Netherlands) and some other localities, numerous foraminifers of the family Polymorphinidae with complete fistulose apertures have been found. These apertures, which are equipped with circular openings and auxiliary apertural chambers, branching and numerous narrow projecting tubes or stolons, have been widely reported, but their role has been the subject of controversy. The Dutch material shows the foraminifers attached with the apertural tubes to fragments of bryozoan colonies or molluscan shells, suggesting that the tubes could perhaps act as holdfast organs. Most specimens were found in calcarenites of the nearshore facies. The foraminifers cannot be treated as symbiotic organisms nor parasites but as epifauna in search of protection from mechanical destruction by waves and current action. The present case may be best explained as an adaptation of sessile foraminifers with fragile hyaline tests to live in highly disadvantageous, high-energy conditions. 0 Foraminifera, Polymorphinidae, Bryozoa, Upper Cretaceous, Paleocene.

Upper Permian reef complex in the basinal facies of the Zechstein Limestone (Ca1), western Poland

“…Through attachment of foraminifers to dead bryozoans, the foraminiferans benefited from the provision of a sheltered substrate in high‐energy environments (cf. Pożaryska and Voigt, ).…”

Palaeoecology and evolution of marine hard substrate communities

“…According to Thomsen (1977), encrusting bryozoans from Danian mounds in Denmark preferred to attach to erect bryozoans with smooth rather than ridged surfaces. Pozaryska and Voigt (1985) made a detailed study of fistulose foraminiferans attached to erect and vagile bryozoans of Upper Cretaceous and Palaeocene age. They concluded that attachment could occur to both dead and living bryozoans, the foraminiferans benefiting from the provision of a sheltered substrate in high-energy environments.…”

Palaeocology of Hard Substrate Faunas from the Cretaceous Qahlah Formation of the Oman Mountains

“…Alternatively, the foraminifers may have lived interstitially on stable clasts below the sediment-water interface, although this idea is not supported by the fact that in examples where the way-up when collected is known, in six cases the foraminifer was only on the upper side of the clast and in no cases was it found only on the underside. There is no morphological Pozaryska and Voigt (1985).…”