Back
Nannoceratopsis gracilis
Nannoceratopsis gracilis Alberti, 1961; emend. Evitt, 1962; emend. Van Helden, 1977
Taxonomic junior synonym: Nannoceratopsis deflandrei, according to Evitt (1962, p.1129–1130) — however, Ilyina et al. (1994, p.12) retained Nannoceratopsis deflandrei.
Locus typicus: Hildesheim, Germany
Stratum typicum: Bajocian
Translation Alberti, 1961: LPP
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Nannoceratopsis gracilis Alberti, 1961, emend. Evitt, 1962, emend. van Helden, 1977 according to van Helden (1977, p.165) has a variable lateral outline. It is subtriangular, with two antapical horns ( ventral horn always much shorter and less well developed than the dorsal horn), to nearly ovoid with a poorly developed ventral horn and a pronounced dorsal horn. Postcingular ventral area above ventral horn and below parasulcal area more or less straight and parallel to apical-antapical axis, sometimes pronounced bulging. Periphragm sculpture reticulate. This emendation restricts the morphology to forms having a distinctly reticulate ornamentation, one dorsal antapical horn and one short ventral antapical horn, which may be poorly developed. It excludes forms having a microreticulate to scabrate or nearly smooth ornamentation and a distinctly ovoid, rounded outline with only the dorsal antapical horn developed. Size: length 72-77 µm, width 47-51 µm..
--------------------------------------------------
Original description: Alberti 196, p. 30: Nannoceratopsis? gracilis
Diagnosis: Shell flattened, outline rounded pentagonal. Lateral sides often convex. Apical horn small, mostly offset. Strong antapical horns not equal in length, diverging and distally narrowing quickly, the tips slightly blunt. Without cingulum. Surface of the shell bearing a net-like sculpture.
Additions: the antapical horns are often shaped like a gothic arch, and mostly one horn is reduced. The short apical horn is distally blunt.
Dimensions: Holotype: length 78 Ám, width 52 Ám. Other specimens: length 72-77 Ám, width 47-51 Ám (11 specimens).
-------------------------------------------------------
Emended diagnosis: Evitt, 1962, p. 1129-1130:
Dinoflagellate synonyms: Nannoceratposis deflandrei Evitt junior to N.? gracilis Alberti
In 1961 Dr. Gerhard Alberti and I published, independently and within a few weeks of each other, descriptions of two new species of Jurassic dinoflagellates that, I believe, are clearly conspecific. Albrrti (1961, p. 39, pl.7, figs. 16,17) based Nannoceratopsis?gracilis on 11 specimens from outcropping Dogger a-¯ at Hildensheim, Germany. I proposed the name Nannoccratopsis deflandrei (Evitt, 1961, pp. 308-312, pl. 1, figs. 1-14, pl. 2, figs. 1-29, text-figs. 5,9-17) for a species represented by several hundred specimens from subsurface Lias d near Randers, Denmark. Although Alberti made the generic assignment with query and described the species only briefly, there is no doubt in my mind that we were dealing with the same species, which is properly assigned to Nannoceratopsis. His two figured specimens fall well within the range of variation displayed by the ones I studied. All critical morphologic features that I attributed to the species can be recognized in Alberti's figures, although he mentions few of them in the text, where, in fact, he states incorrectly that the species is "Ohne Querfurche." In addition, in samples of the Dogger from several wells in northwestern Germany I have subsequently found specimens I would assign to the same species, thus confirming its range from the Lower into the Middle Jurassic. Since Alberti's work was published June 1961, whereas mine did not appear until July, the name Nannocceratopsis deflandrei Evitt is a junior bubjective synonym of Nannoceratopsis gracilis Alberti. My work, therefore emends the specific description of N. gracilis Alberti (chiefly by providing more detailed information on the morphology of the species) and extends downward its known stratigraphic range.
--------------------------------------------------------------------------------------------------------------------------------------------------
Emended diagnosis: Van Helden, 1977, p. 165
Lateral outline variable: subtriangular with two antapical horns (ventral horn always much shorter and less well developed than the dorsal horn) to nearly ovoid with poorly developed ventral horn and a pronounced dorsal horn. Postcingular ventral area above ventral horn and below parasulcal area more or less straight and parallel to apical-antapical axis, sometimes pronouncedly bulging. Periphragm sculpture reticulate. All other features as in Evitt, 1961.
Remark: the emended diagnosis of N. gracilis restricts the morphology of the species to forms having a distinctly reticulate ornamentation, one dorsal antapical horn and one short ventral antapical horn, which may be poorly developed. It excludes forms having a microreticulate to scabrate or nearly smooth ornamentation an d a distinctly ovoid, rounded outline with only the dorsal antapical horn developed.
Poulsen 1996 p.55 Pl. 37, Figs. 1-8, Pl. 40, Figs. 4-5
Remarks. The ectophragm of figured specimens from the Late Toarcian of Germany shows weak granulation and finer and more widely spaced perforations than the specimens of N. gracilis figured by Piel and Evitt (1980).
Recorded occurrences. Denmark: L. spinosa Zone, Subzone b to top? of Nannoceratopsis gracilis Superzone.
Taxonomic junior synonym: Nannoceratopsis deflandrei, according to Evitt (1962, p.1129–1130) — however, Ilyina et al. (1994, p.12) retained Nannoceratopsis deflandrei.
Locus typicus: Hildesheim, Germany
Stratum typicum: Bajocian
Translation Alberti, 1961: LPP
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Nannoceratopsis gracilis Alberti, 1961, emend. Evitt, 1962, emend. van Helden, 1977 according to van Helden (1977, p.165) has a variable lateral outline. It is subtriangular, with two antapical horns ( ventral horn always much shorter and less well developed than the dorsal horn), to nearly ovoid with a poorly developed ventral horn and a pronounced dorsal horn. Postcingular ventral area above ventral horn and below parasulcal area more or less straight and parallel to apical-antapical axis, sometimes pronounced bulging. Periphragm sculpture reticulate. This emendation restricts the morphology to forms having a distinctly reticulate ornamentation, one dorsal antapical horn and one short ventral antapical horn, which may be poorly developed. It excludes forms having a microreticulate to scabrate or nearly smooth ornamentation and a distinctly ovoid, rounded outline with only the dorsal antapical horn developed. Size: length 72-77 µm, width 47-51 µm..
--------------------------------------------------
Original description: Alberti 196, p. 30: Nannoceratopsis? gracilis
Diagnosis: Shell flattened, outline rounded pentagonal. Lateral sides often convex. Apical horn small, mostly offset. Strong antapical horns not equal in length, diverging and distally narrowing quickly, the tips slightly blunt. Without cingulum. Surface of the shell bearing a net-like sculpture.
Additions: the antapical horns are often shaped like a gothic arch, and mostly one horn is reduced. The short apical horn is distally blunt.
Dimensions: Holotype: length 78 Ám, width 52 Ám. Other specimens: length 72-77 Ám, width 47-51 Ám (11 specimens).
-------------------------------------------------------
Emended diagnosis: Evitt, 1962, p. 1129-1130:
Dinoflagellate synonyms: Nannoceratposis deflandrei Evitt junior to N.? gracilis Alberti
In 1961 Dr. Gerhard Alberti and I published, independently and within a few weeks of each other, descriptions of two new species of Jurassic dinoflagellates that, I believe, are clearly conspecific. Albrrti (1961, p. 39, pl.7, figs. 16,17) based Nannoceratopsis?gracilis on 11 specimens from outcropping Dogger a-¯ at Hildensheim, Germany. I proposed the name Nannoccratopsis deflandrei (Evitt, 1961, pp. 308-312, pl. 1, figs. 1-14, pl. 2, figs. 1-29, text-figs. 5,9-17) for a species represented by several hundred specimens from subsurface Lias d near Randers, Denmark. Although Alberti made the generic assignment with query and described the species only briefly, there is no doubt in my mind that we were dealing with the same species, which is properly assigned to Nannoceratopsis. His two figured specimens fall well within the range of variation displayed by the ones I studied. All critical morphologic features that I attributed to the species can be recognized in Alberti's figures, although he mentions few of them in the text, where, in fact, he states incorrectly that the species is "Ohne Querfurche." In addition, in samples of the Dogger from several wells in northwestern Germany I have subsequently found specimens I would assign to the same species, thus confirming its range from the Lower into the Middle Jurassic. Since Alberti's work was published June 1961, whereas mine did not appear until July, the name Nannocceratopsis deflandrei Evitt is a junior bubjective synonym of Nannoceratopsis gracilis Alberti. My work, therefore emends the specific description of N. gracilis Alberti (chiefly by providing more detailed information on the morphology of the species) and extends downward its known stratigraphic range.
--------------------------------------------------------------------------------------------------------------------------------------------------
Emended diagnosis: Van Helden, 1977, p. 165
Lateral outline variable: subtriangular with two antapical horns (ventral horn always much shorter and less well developed than the dorsal horn) to nearly ovoid with poorly developed ventral horn and a pronounced dorsal horn. Postcingular ventral area above ventral horn and below parasulcal area more or less straight and parallel to apical-antapical axis, sometimes pronouncedly bulging. Periphragm sculpture reticulate. All other features as in Evitt, 1961.
Remark: the emended diagnosis of N. gracilis restricts the morphology of the species to forms having a distinctly reticulate ornamentation, one dorsal antapical horn and one short ventral antapical horn, which may be poorly developed. It excludes forms having a microreticulate to scabrate or nearly smooth ornamentation an d a distinctly ovoid, rounded outline with only the dorsal antapical horn developed.
Poulsen 1996 p.55 Pl. 37, Figs. 1-8, Pl. 40, Figs. 4-5
Remarks. The ectophragm of figured specimens from the Late Toarcian of Germany shows weak granulation and finer and more widely spaced perforations than the specimens of N. gracilis figured by Piel and Evitt (1980).
Recorded occurrences. Denmark: L. spinosa Zone, Subzone b to top? of Nannoceratopsis gracilis Superzone.