Geology Reference
In-Depth Information
ducers in shallow, low to moderate energetic shelf seas
(Fig. 10.12, Pl. 122/3). They acted as bafflers and con-
tributed to the formation of bioclastic wackestones and
packstones in ramp and outer shelf environments
through fragmentation and transport of their thalli.
Common geographically widespread taxa are
Gymno-
codium
(restricted to the Permian) and
Permocalculus
(Permian to Aptian; Fig. 10.11).
Basics: Udoteacean green algae and gymnocodiacean al
gae
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rouges, Permien-Miocène). Taxonomie, biostratigraphie,
paléogéographie. 3ème partie. Inventaire taxonomique cri-
tiques des espèces de Gymnocodiacées du Permien et du
Trias. - Revue de Micropaléontologie,
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, 23-37
Elliott, G.F. (1955): The Permian alga
Gymnocodium
. - Mi-
cropaleontology,
1
, 83-90
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the Middle East. - Palaeontology,
1
, 254-259
Flügel, E. (1988):
Halimeda:
paleontological record and pa-
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6
, 123-130,
Berlin
Hillis, L. (1991): Recent calcified Halimedaceae. - In: Riding,
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und Taxonomie devonischer Grünalgen am Beispiel
'Lancicula'
. - Sitzungsberichte der Österreichischen Aka-
demie der Wissenschaften, mathematisch-naturwissen-
schaftliche Klasse,
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, 151-161
Mamet, B., Roux, A., Shalaby, H. (1984): Rôle des Algues
calcaires dans la sédimentation Ordovicienne de la plat-
forme du Saint-Laurent. - Geobios, Mémoir Spécial,
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,
261-269
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Halimeda
in late Miocene reefs, southeastern
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6
, 271-279, Berlin
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34
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Fig. 10.13.
Reconstruction of a phylloid algal community.
The algae dominate the sea bottom. The algal leaves are home
to various encrusting foraminifera and polychaete worms.
Brachiopods live in sheltered areas below algal blades. Gas-
tropods and echinids graze the algal meadow. Some bivalves
occur on and within the sediment. Slightly modified from
Toomey (1981).
Roux, A., Deloffre, R. (1990): Révision des Gymnocodiaceae
(algues rouges, Permien-Crétacé). Taxonomie, biostrati-
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32
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Further reading
: K129
10.2.1.6 Phylloid Algae
Definition and morphology:
The informal name re-
fers to the leaflike form of the thalli, which consist of
variously shaped calcified blades comparable in shape
to the modern green alga
Udotea
and to non-calcified
brown algae (Pray and Wray 1963). The fossil record
of these algae consists of fragmented blades exhibiting
various internal structures. Some phylloid algae are dif-
ferentiated into central medullary and cortical zones
(
Anchicodium, Ivanovia, Eugonophyllum
) or consist of
only one layer of pores (
Calcifolium
). The medullary
zone is commonly replaced by coarse sparite. Primary
calcification consists of aragonite. Taxonomic differ-
entiation is based on the structure of the cortex. Some
phylloid algae have internal cellular structures that re-
late them to red algae (
Archaeolithophyllum
, see Sect.
10.2.1.4).
Systematic position:
Most authors place genera of
'phylloid algae' into various groups of green or red al-
gae (Udoteaceae; Peyssoneliaceae). The green algal in-
terpretation is, at least for
Eugonophyllum
, supported
by strong arguments (Kirkland et al. 1993). Some au-
thors include
Eugonophyllum
(Pl. 58/5),
Ivanovia
(Pl.
58/4) and
Anchicodium
in the separate green algal group
Anchicodiaceae.
