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Radiolarian Micropalaeontology:
Morphology and Taxonomy
Professor Simon K. HaslettCentre for Excellence in Learning and Teaching
23rd February 2010
Introduction
• Radiolaria are classified as a Subclass of Sarcodine Protozoa (single-celled).
• Three Orders: Acantharia, Phaeodaria, and Polycystina (the latter is the most significant in micropalaeontology).
• Secrete silica (SiO2) tests (cf. shells).
• They are marine holoplankton.
Polycystine Radiolaria
• Polycystine Radiolaria comprise two major Suborders:
• 1) Spumellaria 2) Nassellaria.Spine
Cortical Shell with Pores
Inner Medullary Shell(s) connected to the Cortical Shell by radial bars or beams
Cephalis
Thorax
Abdomen
Post-abdominal segments
Spumellarian Morphology 1
a) Cortical shell only, usually with pores.
b) Medullary and cortical shells and spines.
c) Shells and polar spines that are connected by an external circular ring.
d) Medullary and a constricted cortical shell with polar caps.
Spumellarian Morphology 2
a) discoidal and lenticular forms, with medullary and cortical shells, sometimes with protruding spines.
b) spongy shells are common in a number of different forms.
c) gated forms occur due to encircling girdles.
Nassellarian Morphology 1• Spicule
– Apical spine– Sagittal ring– Vertical spine– Cephalis (elementary)– Median bar (short)– Lateral spine (vestige)– Dorsal spine (vestige)
Nassellarian Morphology 2
a) cephalis only (here with some feet).
b) cephalis and thorax only (here with large cephalic horns and abdominal feet).
c) cephalis, thorax, and abdomen only (with horn).
d) as in c) plus one post-abdominal segment
e) as in d) plus three or four post-abdominal segments
Other Morphological Features
a) perforate plate pores.
b) spongy pores. c) rectangular (left) and polygonal or honey-combed (right) pores.
d) circular pores.
e) cephalic tube.
f) peristome around the aperture.
g) teeth around the aperture.
Major Taxonomic Groups
• There are numerous taxonomic groups and thousands of species, but their classification has proved problematic to generations of taxonomists.
• Examples of a number of the most frequently encountered Quaternary Spumellarian and Nassellarian taxa are:
Collosphaerids
Saturnalins Cubosphaerins
Artiscids Phacodiscids
Spongopylins Spongasterins
Dictyocorins
Spongurins
Pylonids Acanthodesmids
Carpocanids
Eucyrtidins
Theocalyptrins
Plectopyramins
Pterocorids
Artostrobids
Cannobotryids
Summary
• This presentation included:– An introduction to Polycystine Radiolaria.– General morphology of Spumellarian and
Nassellarian Polycystine Radiolaria.– An introduction to radiolarian taxonomic
forms common in Quaternary studies.– A guide to further reading on the topic.
Further Reading
• Anderson, O. R., 1983. Radiolaria. Springer-Verlag, New York.
• Armstrong, H. A., Brasier, M. D., 2005. Microfossils (2nd Ed). Blackwell, Oxford.
• Casey, R. E., 1993. Radiolaria. In: Lipps, J. H. (ed.) Fossil Prokaryotes and Protists. Blackwell, Oxford, pp. 249-84.
• Nigrini, C., Moore, T. C. Jr, 1979. A Guide to Modern Radiolaria. Cushman Foundation for Foraminiferal Research, Special Publication No. 16.
This resource was created by the University of Wales, Newport and released as an open educational resource through the 'C-change in GEES' project exploring the open licensing of climate change and sustainability resources in the Geography, Earth and Environmental Sciences. The C-change in GEES project was funded by HEFCE as part of the JISC/HE Academy UKOER programme and coordinated by the GEES Subject Centre.
This resource is licensed under the terms of the Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales license (http://creativecommons.org/licenses/by-nc-sa/2.0/uk/).
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Author Professor Simon K. Haslett
Research Assistant Jonathan Wallen
Institute - Owner University of Wales, Newport
Title Radiolarian Micropalaeontology: Morphology and Taxonomy
Description An introduction to Polycystine Radiolaria
Date Created 2010
Educational Level Higher
Keywords UKOER, GEESOER, Microfossil, Radiolaria
Creative Commons License Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales
