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Amphorula
From Williams et al., 2017:
[Amphorula, Dodekova, 1969, p. 19; Emendations: Zotto et al., 1987, p. 203; Monteil, 1990, p. 602
Type species: Amphorula metaelliptica, Dodekova, 1969 (pl.4, figs.1–3)]
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Original description: [Dodekova, 1969]: (Translation: Stover and Evitt 1978, p. 16)
Diagnosis:
Body ellipsoidal to spherical, with fields arranged around an equatorial region - the transverse furrow. Fields are semi-elliptical, open towards the furrow, and from which extend the curved fan-shaped appendices. Furrows (transverse and longitudinal) are reflected by the small appendices. Reflected tabulation - 1-4`?, 6``, 6s.t., 6```, 1p, 1ppl, 1````. Archeopyle is apical with a zig-zag outline.
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Modified description:
Stover and Evitt 1978, p. 16:
Synopsis:
Cysts proximochorate, body subspherical; paratabulation gonyaulacacean, indicated by typically high arcuate penitabular septa that are incomplete along the paracingulum; latter with rectilinear septa; archeopyle apical, Type tA.
Description:
Shape: Body subspherical.
Wall Relationships: Autophragm only.
Wall features: No parasutural features. Penitabular septa arcuate, typically high, incomplete, open towards paracingulum; latter with rectilinear septa; small paraplates may be indicated by trumpet-shaped or tapered processes. Septa perforate and denticulate or smooth distally.
Paratabulation: Indicated by arcuate penitabular septa and by rectilinear septa; gonyaulacacean, formula: ?1-4`, 6``, 6c, 6```, 1p, 1````, 1-3s. Septa on paraplates 1p and 1```` normally complete and circular to rectangular in outline.
Archeopyle: Apical, Type tA; principal archeopyle suture zigzag with deep parasulcal notch; operculum free; shapes and number of septa on operculum unknown.
Paracingulum: Indicated by six slender elongate (rectilinear) septa.
Parasulcus: Indicated by one to three complete septa or processes.
Size: Intermediate.
Affinities:
Amphorula differs from Hemiplacophora and Schematophora in having rectilinear septa in the paracingular area; such features are not present in the other two genera. Amphorula differs further from Schematophora in having penitabular septa that are incomplete, whereas nearly all of the septa in Schematophora are complete.
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Emended descriptions:
Zotto et al., 1987:
Description:
An important feature of the genus Amphorula is the nature of the processes in the cingulum, which serves as a major character which distinguishes this from other related genera as Alisocysta and Atlantodinium. In these genera, the cingulum is constructed of transversely elongated rectangular or elliptical penitabular septa.
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Poulsen, 1996, p. 64-65:
Discussion: Amphorula-Pensseiasphaeridium-Systematophora complex:
The species included within these three genera have a combination of intratabular annulate-arcuate ridges or processes, or large, often deeply digitate processes in the precingular and postcingular paraplate series, and solid cingular processes linked in pairs by a low ridge. Generic differentiation depends on ridge/process morphology, i.e. annulate to arcuate septa in Amphorula; annulate to arcuate complexes composed of simple to complex-linked processes in Systematophora; and tubiform, simple to deeply digitate and fenestrate processes in Perisseiasphaeridium. However, some specimens of Systematophora areolata have processes reduced in length, showing the relationship with Amphorula. In contrast, when the processes of Systematophora are long and the annulate complex becomes narrow at the base, these process complexes are very similar to the processes of, for example, Perisseiasphaeridium pannosum. In one specimen (Pl. 30, Fig. 6), the process complexes on the epicyst are of the Systematophora areolata type, whereas the tubiform processes on the hypocyst are of P. pannosum type.
The Amphorula-Perisseiasphaeridium-Systematophora complex is not considered to be a simple lineage. Davey (1982) regarded Systematophora as the root stock from which early members of the other genera evolved, whereas Stancliffe and Sarjeant (1990) believed that Oligosphaeridium descended from Systematophora, and that Amphorula descended from Taeniophora and Rigaudella and, that both Systematophora and Rigaudella descended from Adnatosphaeridium. Personally, I believe it is more likely that Amphorula descended from Systematophora. Some of the ideas are summarized on Text-Fig. 20, though interrelationships are complex and not fully understood.
Remarks:
Monteil (1990) describes the phyletic evolution of the genus Amphorula. One of the important events is the adcingular opening of the penitabular septa which, according to Monteil (1990), occurs at the transition from the Kimmeridgian to the Tithonian/Volgian. However, Polish Kimmeridgian specimens of Amphorula metaelliptica show a more gradual evolution from adcingularly closed septa through adcingularly open epicystal and closed hypocystal, to adcingularly open septa on both the epicyst and hypocyst. Zotto et al. (1987) suggested that the septa corresponding to smaller paraplates (e.g. 1"`) may be arcuate and septa corresponding to larger paraplates (e.g. 4"` and 5"`) are annulate. Septa which are open adcingularly may possess a low ridge in place of the missing part of the septa. I find that the variation between arcuate and annulate septa cannot be described as simply morphostratigraphic variation, but must be related also to intraspecific variation.
[Amphorula, Dodekova, 1969, p. 19; Emendations: Zotto et al., 1987, p. 203; Monteil, 1990, p. 602
Type species: Amphorula metaelliptica, Dodekova, 1969 (pl.4, figs.1–3)]
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Original description: [Dodekova, 1969]: (Translation: Stover and Evitt 1978, p. 16)
Diagnosis:
Body ellipsoidal to spherical, with fields arranged around an equatorial region - the transverse furrow. Fields are semi-elliptical, open towards the furrow, and from which extend the curved fan-shaped appendices. Furrows (transverse and longitudinal) are reflected by the small appendices. Reflected tabulation - 1-4`?, 6``, 6s.t., 6```, 1p, 1ppl, 1````. Archeopyle is apical with a zig-zag outline.
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Modified description:
Stover and Evitt 1978, p. 16:
Synopsis:
Cysts proximochorate, body subspherical; paratabulation gonyaulacacean, indicated by typically high arcuate penitabular septa that are incomplete along the paracingulum; latter with rectilinear septa; archeopyle apical, Type tA.
Description:
Shape: Body subspherical.
Wall Relationships: Autophragm only.
Wall features: No parasutural features. Penitabular septa arcuate, typically high, incomplete, open towards paracingulum; latter with rectilinear septa; small paraplates may be indicated by trumpet-shaped or tapered processes. Septa perforate and denticulate or smooth distally.
Paratabulation: Indicated by arcuate penitabular septa and by rectilinear septa; gonyaulacacean, formula: ?1-4`, 6``, 6c, 6```, 1p, 1````, 1-3s. Septa on paraplates 1p and 1```` normally complete and circular to rectangular in outline.
Archeopyle: Apical, Type tA; principal archeopyle suture zigzag with deep parasulcal notch; operculum free; shapes and number of septa on operculum unknown.
Paracingulum: Indicated by six slender elongate (rectilinear) septa.
Parasulcus: Indicated by one to three complete septa or processes.
Size: Intermediate.
Affinities:
Amphorula differs from Hemiplacophora and Schematophora in having rectilinear septa in the paracingular area; such features are not present in the other two genera. Amphorula differs further from Schematophora in having penitabular septa that are incomplete, whereas nearly all of the septa in Schematophora are complete.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Zotto et al., 1987:
Description:
An important feature of the genus Amphorula is the nature of the processes in the cingulum, which serves as a major character which distinguishes this from other related genera as Alisocysta and Atlantodinium. In these genera, the cingulum is constructed of transversely elongated rectangular or elliptical penitabular septa.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Poulsen, 1996, p. 64-65:
Discussion: Amphorula-Pensseiasphaeridium-Systematophora complex:
The species included within these three genera have a combination of intratabular annulate-arcuate ridges or processes, or large, often deeply digitate processes in the precingular and postcingular paraplate series, and solid cingular processes linked in pairs by a low ridge. Generic differentiation depends on ridge/process morphology, i.e. annulate to arcuate septa in Amphorula; annulate to arcuate complexes composed of simple to complex-linked processes in Systematophora; and tubiform, simple to deeply digitate and fenestrate processes in Perisseiasphaeridium. However, some specimens of Systematophora areolata have processes reduced in length, showing the relationship with Amphorula. In contrast, when the processes of Systematophora are long and the annulate complex becomes narrow at the base, these process complexes are very similar to the processes of, for example, Perisseiasphaeridium pannosum. In one specimen (Pl. 30, Fig. 6), the process complexes on the epicyst are of the Systematophora areolata type, whereas the tubiform processes on the hypocyst are of P. pannosum type.
The Amphorula-Perisseiasphaeridium-Systematophora complex is not considered to be a simple lineage. Davey (1982) regarded Systematophora as the root stock from which early members of the other genera evolved, whereas Stancliffe and Sarjeant (1990) believed that Oligosphaeridium descended from Systematophora, and that Amphorula descended from Taeniophora and Rigaudella and, that both Systematophora and Rigaudella descended from Adnatosphaeridium. Personally, I believe it is more likely that Amphorula descended from Systematophora. Some of the ideas are summarized on Text-Fig. 20, though interrelationships are complex and not fully understood.
Remarks:
Monteil (1990) describes the phyletic evolution of the genus Amphorula. One of the important events is the adcingular opening of the penitabular septa which, according to Monteil (1990), occurs at the transition from the Kimmeridgian to the Tithonian/Volgian. However, Polish Kimmeridgian specimens of Amphorula metaelliptica show a more gradual evolution from adcingularly closed septa through adcingularly open epicystal and closed hypocystal, to adcingularly open septa on both the epicyst and hypocyst. Zotto et al. (1987) suggested that the septa corresponding to smaller paraplates (e.g. 1"`) may be arcuate and septa corresponding to larger paraplates (e.g. 4"` and 5"`) are annulate. Septa which are open adcingularly may possess a low ridge in place of the missing part of the septa. I find that the variation between arcuate and annulate septa cannot be described as simply morphostratigraphic variation, but must be related also to intraspecific variation.