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Stanfordella fastigiata
Stanfordella fastigiata (Duxbury, 1977, p.36–37, pl.1, figs.8–9,12; text-fig.11) Helenes and Lucas-Clark, 1997, p.183. Emendation: Helenes and Lucas-Clark, 1997, p.184, as Stanfordella fastigiata.
Holotype: Duxbury, 1977, pl.1, figs.8,12; text-fig.11; Jan du Chêne et al., 1986a, pl.43, figs.1–6.
Originally Gonyaulacysta, subsequently (and now) Stanfordella.
Age: early Hauterivian–early Barremian.
Original description: Duxbury, 1977, p. 36
Body outline distinctly pentagonal in optical section. Endophragm smooth to finely granular, rounded polygonal without indication of any apical prominence. Periphragm finely granular, developed into fairly high crests which are characteristically distally denticulate. The individual denticles vary from short,
regularly tapering elements to well-developed ones (particularly bordering the antapical plate) which flare slightly for two-thirds of their length and then taper sharply. Tabulation ?4", 6", ?6""", 1p, 1pv, 1"""". Periphragm produced into a prominent apical horn. Archeopyle formed by loss of plate 3".
Dimensions: Holotype 70x68 µm; overall 81(71)58x78(64)54 µm.
Remarks:
Harding, 1990, p. 32: This species is common in the oldest samples studied, becoming less frequent through the early Barremian and dying out by late Barremian time. In contrast to Duxbury's (1977) specimens, many of those observed in this study show bifurcations of the parasutural septal denticles. The periphragm is interrupted in the parasulcal area, being undeveloped over Im, lu and the flagellar scar region. Paratabulation formula: 2pr, 4", 6", 6c, 6""", 1"""", 1p, 5s. li is very elongated and is only in contact with five paraplates, this results in the loss of the A/li contact as noted by Helenes (1986: 80; text-fig. 4a and d). This is the only modification of the Jurassica paratabulation pattern. A porichnion is developed at the O/A/lu triple junction. No dorsal incidental paraplates have been discerned.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Stanfordella fastigiata (Duxbury, 1977) Helenes and Lucas-Clark, 1997. Emended diagnosis from Helenes and Lucas-Clark (1997, p.184), proximate cysts with subhexagonal body and apical horn. Precingular archeopyle type P4. Peri- and endophragm appressed except under the apical horn and beneath the parasutural ridges. Parasutural features continuous, spiny ridges that define a paratabulation conforming to that of Stanfordella. Intratabular features range from almost smooth walls to numerous, very low, evenly spaced granules (smaller than in S.granosa). Stanfordella fastigiata differs from Rhynchodiniopsis serrata in size which is much larger (100-109 x 94-100 µm), in the detail of denticulation, and the difference in horn structure. Size: Equatorial diameter about 70 µm, body length about 65 µm, height of apical horn about 15 µm. Size, from Duxbury (1977), overall 58-81 x 54-78 µm.
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Holotype: Duxbury, 1977, pl.1, figs.8,12; text-fig.11; Jan du Chêne et al., 1986a, pl.43, figs.1–6.
Originally Gonyaulacysta, subsequently (and now) Stanfordella.
Age: early Hauterivian–early Barremian.
Original description: Duxbury, 1977, p. 36
Body outline distinctly pentagonal in optical section. Endophragm smooth to finely granular, rounded polygonal without indication of any apical prominence. Periphragm finely granular, developed into fairly high crests which are characteristically distally denticulate. The individual denticles vary from short,
regularly tapering elements to well-developed ones (particularly bordering the antapical plate) which flare slightly for two-thirds of their length and then taper sharply. Tabulation ?4", 6", ?6""", 1p, 1pv, 1"""". Periphragm produced into a prominent apical horn. Archeopyle formed by loss of plate 3".
Dimensions: Holotype 70x68 µm; overall 81(71)58x78(64)54 µm.
Remarks:
Harding, 1990, p. 32: This species is common in the oldest samples studied, becoming less frequent through the early Barremian and dying out by late Barremian time. In contrast to Duxbury's (1977) specimens, many of those observed in this study show bifurcations of the parasutural septal denticles. The periphragm is interrupted in the parasulcal area, being undeveloped over Im, lu and the flagellar scar region. Paratabulation formula: 2pr, 4", 6", 6c, 6""", 1"""", 1p, 5s. li is very elongated and is only in contact with five paraplates, this results in the loss of the A/li contact as noted by Helenes (1986: 80; text-fig. 4a and d). This is the only modification of the Jurassica paratabulation pattern. A porichnion is developed at the O/A/lu triple junction. No dorsal incidental paraplates have been discerned.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Stanfordella fastigiata (Duxbury, 1977) Helenes and Lucas-Clark, 1997. Emended diagnosis from Helenes and Lucas-Clark (1997, p.184), proximate cysts with subhexagonal body and apical horn. Precingular archeopyle type P4. Peri- and endophragm appressed except under the apical horn and beneath the parasutural ridges. Parasutural features continuous, spiny ridges that define a paratabulation conforming to that of Stanfordella. Intratabular features range from almost smooth walls to numerous, very low, evenly spaced granules (smaller than in S.granosa). Stanfordella fastigiata differs from Rhynchodiniopsis serrata in size which is much larger (100-109 x 94-100 µm), in the detail of denticulation, and the difference in horn structure. Size: Equatorial diameter about 70 µm, body length about 65 µm, height of apical horn about 15 µm. Size, from Duxbury (1977), overall 58-81 x 54-78 µm.
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