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Parvocavatus tuberosus
Parvocavatus tuberosus Gitmez, 1970
Now Dingodinium?. Originally Parvocavatus, subsequently Dingodinium, thirdly (and now) Dingodinium?.
Holotype: Gitmez, 1970, pl.6, fig.6, text-fig.31
Locus typicus: Kimmeridge Clay from 20 ft. above the Ringstead Coral Bed, Osmington Mills, Dorset (OM 420), England
Stratum typicum: Early Kimmeridgian
Original diagnosis: Gitmez, 1970, p.307
Parvocavatus having an ovoidal-polygonal periblast, with a spheroidal endoblast inside. There is a hollow apical horn at the apex, which is formed by the periphragm only and has a hole at its tip. Reflected tabulation: 4", 6", 6c, 6""", and 1"""". Periphragm thin, endophragm thick, with a densely tuberculate surface. A circular cingulum divides the shell into two nearly equal parts. Apical archaeopyle developed, the operculum typically remaining attached.
Dimensions:
Holotype: overall length 55 µm, breadth 45 µm; endoblast diameters 40 x 40 µm.
Other English specimens (2 specimens measured): overall length 52-56 µm, breadth 46-48 µm; endoblast diameters 38-40 µm.
Range of the French specimens (40 specimens measured): overall length 50-55 µm, breadth 43-45 µm; endoblast diameters 35-45 µm.
All the observed specimens were not capable of measurement.
Original description: Gitmez, 1970, p.307-308
The periblast is ovoidal with a short, blunt apical horn; the endoblast is spherical; both periblast and endoblast have a rounded antapex. The epitract and hypotract are nearly equal in size. The sulcus extends between apex and antapex. On the ventral surface there is a split between the apical and precingular plates, which suggests incipient archaeopyle formation. The presence of a hole at the tip of the apical horn is also noteworthy. The precingular plates are generally large: plate 6" is smaller than the others. Six postcingular plates are present, plate 1""" small and triangular-shaped. A single antapical plate is present; it is quite large and convex.
Affinities:
Gitmez, 1970, p.308: Parvocavatus tuberosus is similar to Gardodinium trabeculosum, but differs in having no processes connecting the two membranes. This new species differs from all previously described species in its combination of the characteristic hole at the tip of the apical horn, archaeopyle formation and tabulation.
P. tuberosus is common in the French material, but it is rare in Dorset and Scottish assemblages. Generally the specimens are badly preserved, so that it was difficult to determine the details of the tabulation.
Now Dingodinium?. Originally Parvocavatus, subsequently Dingodinium, thirdly (and now) Dingodinium?.
Holotype: Gitmez, 1970, pl.6, fig.6, text-fig.31
Locus typicus: Kimmeridge Clay from 20 ft. above the Ringstead Coral Bed, Osmington Mills, Dorset (OM 420), England
Stratum typicum: Early Kimmeridgian
Original diagnosis: Gitmez, 1970, p.307
Parvocavatus having an ovoidal-polygonal periblast, with a spheroidal endoblast inside. There is a hollow apical horn at the apex, which is formed by the periphragm only and has a hole at its tip. Reflected tabulation: 4", 6", 6c, 6""", and 1"""". Periphragm thin, endophragm thick, with a densely tuberculate surface. A circular cingulum divides the shell into two nearly equal parts. Apical archaeopyle developed, the operculum typically remaining attached.
Dimensions:
Holotype: overall length 55 µm, breadth 45 µm; endoblast diameters 40 x 40 µm.
Other English specimens (2 specimens measured): overall length 52-56 µm, breadth 46-48 µm; endoblast diameters 38-40 µm.
Range of the French specimens (40 specimens measured): overall length 50-55 µm, breadth 43-45 µm; endoblast diameters 35-45 µm.
All the observed specimens were not capable of measurement.
Original description: Gitmez, 1970, p.307-308
The periblast is ovoidal with a short, blunt apical horn; the endoblast is spherical; both periblast and endoblast have a rounded antapex. The epitract and hypotract are nearly equal in size. The sulcus extends between apex and antapex. On the ventral surface there is a split between the apical and precingular plates, which suggests incipient archaeopyle formation. The presence of a hole at the tip of the apical horn is also noteworthy. The precingular plates are generally large: plate 6" is smaller than the others. Six postcingular plates are present, plate 1""" small and triangular-shaped. A single antapical plate is present; it is quite large and convex.
Affinities:
Gitmez, 1970, p.308: Parvocavatus tuberosus is similar to Gardodinium trabeculosum, but differs in having no processes connecting the two membranes. This new species differs from all previously described species in its combination of the characteristic hole at the tip of the apical horn, archaeopyle formation and tabulation.
P. tuberosus is common in the French material, but it is rare in Dorset and Scottish assemblages. Generally the specimens are badly preserved, so that it was difficult to determine the details of the tabulation.