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Nannoceratopsis raunsgaardii
Nannoceratopsis raunsgaardii Poulsen 1996
Pl. 35, Figs. 14-15, Pl. 36, Figs. 5-6, Pl. 40, Fig. 3
Nannoceratopsis cf. pellucida Deflandre, 1938, in Dybkjaer, 1991, p. 30, pl. 15, figs. 11-12. Nannoceratopsis cf. triangulata Prauss, 1987 in Poulsen, 1992, pl. 3, figs. A-B, pl. 4, figs. K-l.
Diagnosis. A species of Nannoceratopsis with a subtriangular outline and two antapical horns. The concavity between the two antapical horns is very smoothly curved. The surface is shagreenate to scabrate in transmitted light microscopy and in SEM. In SEM (x 10,000) the surface is granulate to verrucate.
Description: The lateral outline of this species is subtriangular. The two antapical horns are very short and of almost equal length. The concavity between the two antapical horns is less pronounced than in most species of Nannoceratopsis with two antapical horns. The concavity may resemble an almost straight line. The wall structure is similar to that of weakly ornamented Nannoceratopsis senex specimens.
Dimensions: 33 specimens measured. Length of epicyst 5 Ám. Holotype: length 50 Ám, width between horns 58 Ám. Paratype: length 48 Ám, 45 Ám, width between horns 45 Ám. Range (minimum-mean-maximum): overall cyst length 47 Ám - 53 Ám - 59 Ám, overall cyst width 45 Ám - 53 Ám- 56 Ám.
Comparison. Nannoceratopsis raunsgaardii is similar in shape to Nannoceratopsis triangulata Prauss 1987 from which it is distinguished by having a shagreenate to granular wall structure and more blunt antapical horns. Nannoceratopsis triangulata Prauss 1987 has a small protrusion at the end of each antapical horn. Nannoceratopsis spiculata Stover 1966 has longer antapical horns.
In SEM (x 10,000) Nannoceratopsis raunsgaardii is the wall sculpture and structure shagreenate, spongy, perforate to granulate. Nannoceratopsis triangulata Prauss 1987 has a felty (vermiculate meshed) wall structure. Nannoceratopsis gracilis Alberti 1961 has a perforate ectophragm. Nannoceratopsis spiculata Stover 1966 has a wall with an irregular vermiculate mesh as wall structure.
Recorded occurrences. This species is found commonly in the Late Pliensbachian [Ogmoconchella adenticulata - Nanacythere simplex Zone (ostracod zonation)] to the Early Aalenian and is sporadically present in the early part of the Middle Jurassic of Denmark: Aars-1 ST 3 in ditch cuttings 2875-80 m; Fars0-l at 1979.5-1984.5 m (P. nasuta Subzone, M. semitabulatum Zone); Fjerritslev-2 at 1561 m, [L. spinosa Zone, Subzone b, and O. adenticulata-N. simplex Zone, "upper subzone" (ostracod zonation)]; Haldager-1 at 4503 ft. (P. nasuta Subzone, M. semitabulatum Zone); Lav0-1, top occurrence in ditch cuttings at 2108-10 m, (M. semitabulatum Subzone, M. semitabulatum Zone); Sound-2 at 40-47 m, (P. nasuta Subzone, M. semitabulatum Zone, and Pseudomacrocypris subaequabilis ostracod Horizon, Early Aalenian); Sound-3 at 52-72 m, [L. spinosa Zone, Subzone b, and O. adenticulata-N. simplex Zone, "upper subzone" (ostracod zonation)]; Uglev-1 at 3032 ft. (N. gracilis Superzone, Middle Jurassic).
Holotype. Pl. 35, Fig. 15; DGU catalogue no.: 1991-NEP-15; from Lavo-1 borehole at 2143 m, Gassum Formation, Pliensbachian, M. semitabulatum Subzone.
Paratype. Pl. 35, Fig. 14; DGU catalogue no.: 1991-NEP-16; from Lavo-1 borehole at 2110 m, Fjerritslev Formation, Late Pliensbachian - Early Toarcian, M. semitabulatum Subzone.
Pl. 35, Figs. 14-15, Pl. 36, Figs. 5-6, Pl. 40, Fig. 3
Nannoceratopsis cf. pellucida Deflandre, 1938, in Dybkjaer, 1991, p. 30, pl. 15, figs. 11-12. Nannoceratopsis cf. triangulata Prauss, 1987 in Poulsen, 1992, pl. 3, figs. A-B, pl. 4, figs. K-l.
Diagnosis. A species of Nannoceratopsis with a subtriangular outline and two antapical horns. The concavity between the two antapical horns is very smoothly curved. The surface is shagreenate to scabrate in transmitted light microscopy and in SEM. In SEM (x 10,000) the surface is granulate to verrucate.
Description: The lateral outline of this species is subtriangular. The two antapical horns are very short and of almost equal length. The concavity between the two antapical horns is less pronounced than in most species of Nannoceratopsis with two antapical horns. The concavity may resemble an almost straight line. The wall structure is similar to that of weakly ornamented Nannoceratopsis senex specimens.
Dimensions: 33 specimens measured. Length of epicyst 5 Ám. Holotype: length 50 Ám, width between horns 58 Ám. Paratype: length 48 Ám, 45 Ám, width between horns 45 Ám. Range (minimum-mean-maximum): overall cyst length 47 Ám - 53 Ám - 59 Ám, overall cyst width 45 Ám - 53 Ám- 56 Ám.
Comparison. Nannoceratopsis raunsgaardii is similar in shape to Nannoceratopsis triangulata Prauss 1987 from which it is distinguished by having a shagreenate to granular wall structure and more blunt antapical horns. Nannoceratopsis triangulata Prauss 1987 has a small protrusion at the end of each antapical horn. Nannoceratopsis spiculata Stover 1966 has longer antapical horns.
In SEM (x 10,000) Nannoceratopsis raunsgaardii is the wall sculpture and structure shagreenate, spongy, perforate to granulate. Nannoceratopsis triangulata Prauss 1987 has a felty (vermiculate meshed) wall structure. Nannoceratopsis gracilis Alberti 1961 has a perforate ectophragm. Nannoceratopsis spiculata Stover 1966 has a wall with an irregular vermiculate mesh as wall structure.
Recorded occurrences. This species is found commonly in the Late Pliensbachian [Ogmoconchella adenticulata - Nanacythere simplex Zone (ostracod zonation)] to the Early Aalenian and is sporadically present in the early part of the Middle Jurassic of Denmark: Aars-1 ST 3 in ditch cuttings 2875-80 m; Fars0-l at 1979.5-1984.5 m (P. nasuta Subzone, M. semitabulatum Zone); Fjerritslev-2 at 1561 m, [L. spinosa Zone, Subzone b, and O. adenticulata-N. simplex Zone, "upper subzone" (ostracod zonation)]; Haldager-1 at 4503 ft. (P. nasuta Subzone, M. semitabulatum Zone); Lav0-1, top occurrence in ditch cuttings at 2108-10 m, (M. semitabulatum Subzone, M. semitabulatum Zone); Sound-2 at 40-47 m, (P. nasuta Subzone, M. semitabulatum Zone, and Pseudomacrocypris subaequabilis ostracod Horizon, Early Aalenian); Sound-3 at 52-72 m, [L. spinosa Zone, Subzone b, and O. adenticulata-N. simplex Zone, "upper subzone" (ostracod zonation)]; Uglev-1 at 3032 ft. (N. gracilis Superzone, Middle Jurassic).
Holotype. Pl. 35, Fig. 15; DGU catalogue no.: 1991-NEP-15; from Lavo-1 borehole at 2143 m, Gassum Formation, Pliensbachian, M. semitabulatum Subzone.
Paratype. Pl. 35, Fig. 14; DGU catalogue no.: 1991-NEP-16; from Lavo-1 borehole at 2110 m, Fjerritslev Formation, Late Pliensbachian - Early Toarcian, M. semitabulatum Subzone.