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Dracodinium solidum
From Fensome et al., 2019:
Dracodinium solidum Gocht, 1955, p.88; text-figs.3a–b,4a–c,5a–c. Holotype: Gocht, 1955, text-figs.3a–b. Originally (and now) Dracodinium, subsequently Wetzeliella. Costa and Downie (1979, p.43) retained this species in Dracodinium. Age: Eocene or Oligocene.
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Original description (Gocht, 1955) Translation PKB 2025
Diagnosis. See diagnosis of the genus.
Stratum typicalum: Eocene or Oligocene? (see Remarks).
Locus typicalus: Jatznick near Pasewalk, Pomerania.
Description and notes: The membrane is relatively tough, light to dark reddish-brown, and only becomes transparent when embedded. The carapace is strongly domed, its surface smooth or finely granulated. An apical horn is missing, the apex is rounded; occasionally, a small point is indicated. Only a single specimen showed a lobed projection at the apex, which can be interpreted as a greatly reduced apical horn. The lateral horns vary somewhat in shape. They are distinctly distinct, flat, blunted at the free end, or notched, forming two short lobes. Of the anta-apical horns, only one is well developed, usually the left one. It is pointed or thorn-shaped, flat, and pointed or blunt at the end. In four cases, it is excessively long and ends in a thin tube, which may be slashed several times. The other anta-pical horn, if present, is connected to the first, but forms only a small bulge or a short tip. It is often missing entirely. The inner capsule is largely fitted laterally to the outer edge of the carapace. In somewhat more elongated forms, it is rounded, kite-shaped to oval when viewed from the front, in others it is approximately round. The space between capsule and carapace is usually narrow along the lateral edge; the two shells often touch. They appear to lie on top of each other on the front and back. Sometimes the capsule gives the impression of being double-walled, but this is difficult to determine due to the relatively thick membrane and the often strong curvature. In all well-preserved specimens, an escape hole can be seen, located just below the apex, sometimes almost quite apically. Its shape is roughly the same as in Rhombodinium; it also tapers towards the apex. In three cases the carapace is still closed, but the escape hole is preceded by a suture line. Sometimes the corresponding lid is still found inside the capsule; in one example there are even two lids, that of the outer shell and that of the capsule.
The bristles on the shell are quite varied and irregular. Generally, they can be described as sparse. The bristles vary in length, are hair-like, and only rarely are slightly flared at the ends. They can also vary considerably in the development of the horns and the position of the eclosion hole; however, I would like to classify them as belonging to the same species because of the numerous, well-defined transitional forms.
Occurrence: 45 specimens are known to date. Some of these (3) were found in Intereocene drill samples from the Aldorf oil field in the Diepholz district. The vast majority and best-preserved pieces, however, come from a Tertiary clay from Jatznick near Pasewalk, whose geological age (Eocene or Oligocene) is, to my knowledge, still disputed. Based on comparative studies, I hope to be able to show in a future paper that the association of the planktons of this clay (hystrichospheres, etc.) also seems to point to the (Lower) Eocene. For now, however, the question of age is expressly left open.
Dimensions: Type: Length = 97 µ, width = 113 µ, capsule = 71:69 µ; lateral horns = 21 and 22 µ, antapical horn = 21 µ (each measured from the edge of the capsule). Other specimens vary in length between 103 and 125 µ, in width between 104 and 127 µ. The hatch hole averages 25:34 µ.
Dracodinium solidum Gocht, 1955, p.88; text-figs.3a–b,4a–c,5a–c. Holotype: Gocht, 1955, text-figs.3a–b. Originally (and now) Dracodinium, subsequently Wetzeliella. Costa and Downie (1979, p.43) retained this species in Dracodinium. Age: Eocene or Oligocene.
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Original description (Gocht, 1955) Translation PKB 2025
Diagnosis. See diagnosis of the genus.
Stratum typicalum: Eocene or Oligocene? (see Remarks).
Locus typicalus: Jatznick near Pasewalk, Pomerania.
Description and notes: The membrane is relatively tough, light to dark reddish-brown, and only becomes transparent when embedded. The carapace is strongly domed, its surface smooth or finely granulated. An apical horn is missing, the apex is rounded; occasionally, a small point is indicated. Only a single specimen showed a lobed projection at the apex, which can be interpreted as a greatly reduced apical horn. The lateral horns vary somewhat in shape. They are distinctly distinct, flat, blunted at the free end, or notched, forming two short lobes. Of the anta-apical horns, only one is well developed, usually the left one. It is pointed or thorn-shaped, flat, and pointed or blunt at the end. In four cases, it is excessively long and ends in a thin tube, which may be slashed several times. The other anta-pical horn, if present, is connected to the first, but forms only a small bulge or a short tip. It is often missing entirely. The inner capsule is largely fitted laterally to the outer edge of the carapace. In somewhat more elongated forms, it is rounded, kite-shaped to oval when viewed from the front, in others it is approximately round. The space between capsule and carapace is usually narrow along the lateral edge; the two shells often touch. They appear to lie on top of each other on the front and back. Sometimes the capsule gives the impression of being double-walled, but this is difficult to determine due to the relatively thick membrane and the often strong curvature. In all well-preserved specimens, an escape hole can be seen, located just below the apex, sometimes almost quite apically. Its shape is roughly the same as in Rhombodinium; it also tapers towards the apex. In three cases the carapace is still closed, but the escape hole is preceded by a suture line. Sometimes the corresponding lid is still found inside the capsule; in one example there are even two lids, that of the outer shell and that of the capsule.
The bristles on the shell are quite varied and irregular. Generally, they can be described as sparse. The bristles vary in length, are hair-like, and only rarely are slightly flared at the ends. They can also vary considerably in the development of the horns and the position of the eclosion hole; however, I would like to classify them as belonging to the same species because of the numerous, well-defined transitional forms.
Occurrence: 45 specimens are known to date. Some of these (3) were found in Intereocene drill samples from the Aldorf oil field in the Diepholz district. The vast majority and best-preserved pieces, however, come from a Tertiary clay from Jatznick near Pasewalk, whose geological age (Eocene or Oligocene) is, to my knowledge, still disputed. Based on comparative studies, I hope to be able to show in a future paper that the association of the planktons of this clay (hystrichospheres, etc.) also seems to point to the (Lower) Eocene. For now, however, the question of age is expressly left open.
Dimensions: Type: Length = 97 µ, width = 113 µ, capsule = 71:69 µ; lateral horns = 21 and 22 µ, antapical horn = 21 µ (each measured from the edge of the capsule). Other specimens vary in length between 103 and 125 µ, in width between 104 and 127 µ. The hatch hole averages 25:34 µ.