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Xiphophoridium alatum
Xiphophoridium alatum, Cookson and Eisenack, 1962b, p.487–488; Emendation: Sarjeant, 1966b, p.147, 148
NOW Dinopterygium. Originally Hystrichodinium, subsequently Xiphophoridium, thirdly Pyramidium (generic name illegitimate), fourthly Oodnadattia, fifthly (and now) Dinopterygium. Below, 1981, transferred this species to Oodnadattia Eisenack and Cookson, 1960. Lentin and Williams, 1981, retained it in Xiphophoridium.
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Xiphophoridium alatum (Cookson and Eisenack, 1962b) Sarjeant, 1966b, emend. Sarjeant, 1966b. According to Sarjeant (1966b, p.147), this species has plates bounded by high crests bearing long, dagger-like spines. The cingulum is weakly spiral and bordered by especially high crests. Surface may be smooth to tuberculate. The archeopyle is apical. However, MacRae (1998) has shown that there are all stages of gradation between X.alatum and Dinopterygium cladoides, with the archeopyle being a disintegration archeopyle eventually involving all the epicystal plates. Size: holotype overall length 125 µm, width 96 µm, central body length 70 µm, width 52 µm, range, overall length 100-120 µm, overall width 92-102 µm
Holotype: Cookson and Eisenack, 1962, pl.2, fig.1
Locus typicus: Perth Basin, Freemantle Trafic Bridge, Bore No. 5
Stratum typicum: Albian-Cenomanian
Original description: Cookson and Eisenack 1962 (as Hystrichodinium alatum):
Diagnosis: Shell oval to nearly globular, divided equally by a slightly helicoid girdle. Shell membrane thin, two-layered, outer membrane forming conspicuous wings at apex, antapex, and about the girdle, in which regions it is prolonged into a relatively large number of hollow tapering processes which are arranged in well-defined whorls. Shell tabulated, with pre- and postequatorial plates and apparently one antapical plate; otherwise the tabulation could not be determined. The surface of the plates is ornamented with minute tubercular thickenings which taper to sharp points.
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Emended description: Sarjeant, 1966:
Diagnosis: A Xiphophoridium having an ovoidal to nearly globular shell, shell wall thin. Tabulation ?4', 1a, 6'', 6''', ?op, 1''''; plates bounded by very high crests bearing long, dagger-like spines, crest curving inwards between bases of spines. Cingulum weakly spiral, of moderate breadth and bordered by especially high crests; sulcus also of moderate breadth, extending to antapex. Shell surface not, or only minutely, granular, bearing numerous tubercles, sometimes apparently arranged to plate margins, generally without obvious arrangement. Apical archaeopyle present.
Description:
This species occurs infrequently throughout the English Cenomanian, some 20 specimens having been encountered. The specimens figured, seen in terminal view, was the best-preserved and allowed determination of the tabulation: all other specimens were damaged, or distorted to some extent. It was not possible to prepare a satisfactory figure. The shape of the archaeopyle is that of a ragged polygon with a narrow sulcal notch, suggesting that four apical plates were originally present. Six precingular plates are present, plate 6'' being reduced to accommodate a quadrate anterior intercalary plate. Six postcingular plates are present; no posterior intercalary plate could be distinguished in the specimens studied. The antapex is occupied by a single polygonal plate. The cingulum is weakly spiral, laevorotatory; its structure was not clear in the English specimens, but the photographs of the Australian specimens suggest a division into cingular plates. The crests are delicate, not or only minutely perforate: the spines arise simply as outgrowths of the crests and are somewhat flattened and dagger-like. The shell wall appears to lack ornament other than the tubercles.
Dimensions:
Range of Australian specimens: overall lengths 100-102 µm; overall breadths 92-100 µm.
As a result of orientation or preservation, it did not prove possible to obtain detailed measurements of the English specimens, but dimensions appear comparable.
NOW Dinopterygium. Originally Hystrichodinium, subsequently Xiphophoridium, thirdly Pyramidium (generic name illegitimate), fourthly Oodnadattia, fifthly (and now) Dinopterygium. Below, 1981, transferred this species to Oodnadattia Eisenack and Cookson, 1960. Lentin and Williams, 1981, retained it in Xiphophoridium.
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Xiphophoridium alatum (Cookson and Eisenack, 1962b) Sarjeant, 1966b, emend. Sarjeant, 1966b. According to Sarjeant (1966b, p.147), this species has plates bounded by high crests bearing long, dagger-like spines. The cingulum is weakly spiral and bordered by especially high crests. Surface may be smooth to tuberculate. The archeopyle is apical. However, MacRae (1998) has shown that there are all stages of gradation between X.alatum and Dinopterygium cladoides, with the archeopyle being a disintegration archeopyle eventually involving all the epicystal plates. Size: holotype overall length 125 µm, width 96 µm, central body length 70 µm, width 52 µm, range, overall length 100-120 µm, overall width 92-102 µm
Holotype: Cookson and Eisenack, 1962, pl.2, fig.1
Locus typicus: Perth Basin, Freemantle Trafic Bridge, Bore No. 5
Stratum typicum: Albian-Cenomanian
Original description: Cookson and Eisenack 1962 (as Hystrichodinium alatum):
Diagnosis: Shell oval to nearly globular, divided equally by a slightly helicoid girdle. Shell membrane thin, two-layered, outer membrane forming conspicuous wings at apex, antapex, and about the girdle, in which regions it is prolonged into a relatively large number of hollow tapering processes which are arranged in well-defined whorls. Shell tabulated, with pre- and postequatorial plates and apparently one antapical plate; otherwise the tabulation could not be determined. The surface of the plates is ornamented with minute tubercular thickenings which taper to sharp points.
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Emended description: Sarjeant, 1966:
Diagnosis: A Xiphophoridium having an ovoidal to nearly globular shell, shell wall thin. Tabulation ?4', 1a, 6'', 6''', ?op, 1''''; plates bounded by very high crests bearing long, dagger-like spines, crest curving inwards between bases of spines. Cingulum weakly spiral, of moderate breadth and bordered by especially high crests; sulcus also of moderate breadth, extending to antapex. Shell surface not, or only minutely, granular, bearing numerous tubercles, sometimes apparently arranged to plate margins, generally without obvious arrangement. Apical archaeopyle present.
Description:
This species occurs infrequently throughout the English Cenomanian, some 20 specimens having been encountered. The specimens figured, seen in terminal view, was the best-preserved and allowed determination of the tabulation: all other specimens were damaged, or distorted to some extent. It was not possible to prepare a satisfactory figure. The shape of the archaeopyle is that of a ragged polygon with a narrow sulcal notch, suggesting that four apical plates were originally present. Six precingular plates are present, plate 6'' being reduced to accommodate a quadrate anterior intercalary plate. Six postcingular plates are present; no posterior intercalary plate could be distinguished in the specimens studied. The antapex is occupied by a single polygonal plate. The cingulum is weakly spiral, laevorotatory; its structure was not clear in the English specimens, but the photographs of the Australian specimens suggest a division into cingular plates. The crests are delicate, not or only minutely perforate: the spines arise simply as outgrowths of the crests and are somewhat flattened and dagger-like. The shell wall appears to lack ornament other than the tubercles.
Dimensions:
Range of Australian specimens: overall lengths 100-102 µm; overall breadths 92-100 µm.
As a result of orientation or preservation, it did not prove possible to obtain detailed measurements of the English specimens, but dimensions appear comparable.