Upper Devonian (Frasnian) Radiolarian Fauna from the Gogo Formation, Western Australia

Abstract

Sixteen polycystine radiolarian species recovered from a single sample of the Gogo Formation, Western Australia, are described and illustrated. The material derives from one of the samples used by Glenister and Klapper (1966) for their conodont zonation of the Canning Basin and is of Polygnathus asymmetrica Zone age. The well-preserved radiolarians include Ceratoikiscum, Palaeoscenidium, and representatives of seven genera similar to entactinid forms known especially in Ohio (Foreman 1963), in the Urals (Nazarov 1975), and Byelorussia (Nazarov and Kruycheck 1977). Somewhat surprisingly, and apparently because of differences in stratigraphic level or biofacies, there is less similarity to the radiolarian assemblage of the Gogo Formation recently described by Nazarov, Cockbain and Playford (1982). Newly described taxa include one new genus, Helenifore, and four new species, Helenifore laticlavium, Helioentactinia perjucunda, Spongentactinella corynacantha, and Ceratoikiscum vimenum. INTRODUCTION As a result of the pioneering work of Helen Foreman on structurally preserved, free specimens of Upper Devonian radiolaria and the continued work on such forms in other widely separated Devonian sections such as the Urals (Nazarov 1975), Alaska (Holdsworth et al. 1978) and Australia (Nazarov et al. 1982), it has become apparent that there is a high level of similarity among contemporaneous Devonian faunas around the world. This is not surprising, in view of the presumed planktic life habit of even ancient Radiolaria and the known wide distribution of other Devonian putative plankton such as conodonts. It suggests that with sufficient documentation of their distribution, Devonian radiolarians could be used to supplement existing Devonian biostratigraphic schemes. What is lacking at this point is sufficient documentation of well-preserved Devonian Radiolaria at various locations as a control for their vertical and lateral distribution. We hope that the present paper will contribute in a small way to the need. The assemblage at hand is also sufficiently different from one recently described by Nazarov et al. (1982) from a similar geographic and stratigraphic position, to provide an instructive contrast. Comparison of material studied with that of Nazarov et al. (1982) The differences between our collection and that of Nazarov et al. 1982 are summarized in table 1. The most conspicuous are the presence of ceratoikiscids (4 species) in the material studied by us and their absence from sample 19656 (Nazarov et al.). Further major differences are the presence in our material only of the entactinid genera Helioentactinia and Haplentactinia and the presence in sample 19656 only of Polyentactinia and Somphoentactinia. Such presence-absence contrasts, of course, may reflect inadequate sampling or differences in preservation. It is important to note in this connection that our material is better preserved than that in sample 19656, and that could contribute to its greater diversity. Preservational differences do not, however, seem to be the whole story. There are differences at the species and subspecies level between the two collections that suggest the influence of other factors, such as slight differences in stratigraphic level or biofacies. The former is probable if not presently provable, as our sample is derived from the upper part of the Gogo Formation, whereas sample 19656, coming from 4 km south of Long's Well, must be nearer the base of the Gogo Formation. Differences at the species level between the representation in these two collections of such genera as Astroentactinia, Spongentactinella, and Entactinia may well have a biostratigraphic basis. micropaleontology, vol. 29, no. 4, pp. 454-466, pls. 1-2, 1983 454 This content downloaded from 207.46.13.105 on Wed, 25 May 2016 04:52:06 UTC All use subject to http://about.jstor.org/terms Micropaleontology, vol. 29, no. 4, 1983