Pleuroceras Hyatt, 1867

Bardin, Jérémie, Rouget, Isabelle & Cecca, Fabrizio, 2013, Late Pliensbachian (Early Jurassic) ammonites from Lac de Charmes (Haute-Marne, France): Systematic, biostratigraphy and palaeobiogeography, Geodiversitas 35 (2), pp. 309-334 : 324-326

Genus Pleuroceras Hyatt, 1867

Paltopleuroceras Buckman, 1898: 453 (objective synonym).

TYPE SPECIES. — Ammonites spinatus Bruguière, 1789 (by subsequent designation of Fischer [1887]).

STRATIGRAPHICAL DISTRIBUTIONS. — Late Pliensbachian, Margaritatus chronozone, top of the Gibbosus subchronozone up to Spinatum chronozone , end of the Hawskerense subchronozone. Haute-Marne: bed 8 to 16a (first outcrop) and bed 20 to 32 (second outcrop).

DIAGNOSIS. — Ľe shell is evolute with elliptical to quadrilateral whorl sections. Ľe ventral area brings a strong, crenulated keel bordered by flat areas or shallow to deep sulci. Ľese are formed by projected sharpraised ribs on the ventro-lateral margin of the whorl. In some specimens or during the ontogeny the keel can lose crenulations to become smooth. On the flanks, the ornamentation consists in strong ribs that can develop tubercles on the ventro-lateral edge and can be raised near the umbilical edge.

Pleuroceras transiens ( Frentzen, 1937) ( Figs 5 M-O; 6A-E; Table 3)

Amaltheus margaritatus var. transiens Frentzen, 1937: 99 , pl. 4, figs 22-27.

Pleuroceras transiens – Howarth 1958: pl. 4, figs 16, 17. —? Bourdenet 1964: pl. 1, figs 1, 2. — Mattéi 1985: pl. 9, fig. 3. — Meister 1988: pl. 6, figs 4, 5.

TYPE MATERIAL. — Ľe specimen of Frentzen (1937: pl. 4, fig. 26) has been secondly designated as lectotype by Howarth (1956).

SPECIMENS AVAILABLE. — UPMC-165-167, 174-182, 184.

STRATIGRAPHICAL DISTRIBUTION. — Late Pliensbachian. Ľis species occurs close to the boundary between the Margaritatus and Spinatum Chronozones. Haute-Haute- Marne: bed 8 up to 9.

GEOGRAPHIC DISTRIBUTION. — South-EastFrance,Causses ( Monestier 1913, 1916, 1928; Mattéi 1985; Meister 1989; Morard 2004); eastern France, Burgundy ( Tintant et al. 1961), Franche-Comté ( Bourdenet 1964) andHaute-Marne (this work); North-West Germany ( Jordan 1971); South- West Germany ( Frentzen 1934; Urlichs 1977); South-East Germany (Hoffman et al. 2007); Scotland ( Howarth 1958); Italy, Lombardy Basin ( Wiendenmayer 1980).

DESCRIPTION

Ľe shell is moderately evolute with quadrilateral whorl section and rounded ventro-lateral edges. Ribs are relatively strong without the typical ventrolateral sharp-raised ribs of Pleuroceras . Ľe keel is crenulated by strong individualized chevrons sometimes in connection with ribs.

DISCUSSION

Pleuroceras transiens differs from A. margaritatus by the lower whorl section, associated to a stronger forward projection of the ribs on the ventro-lateral edge. Other species of Pleuroceras have sharp-raised ribs on this ventro-lateral edge. Howarth (1956) designated the specimen (Quenstedt 1885: pl. XLI, fig. 5) as the lectotype of A. bechteri , thus A. bechteri is a synonym of A. salebrosum .

Pleuroceras solare s.s. ( Phillips, 1829) ( Fig. 7B, C ; Table 3)

Ammonites solaris Phillips, 1829: 135 , pl. 4, fig. 29.

Ammonites regularis Simpson, 1855: 89.

Ammonites costatus nudus Quenstedt, 1885: 334, pl. 42, fig. 19.

Paltopleuroceras pseudocostatum – Richardson 1904: 215, pl. 24, fig. 10. — Buckman S. S. 1913: pl. 77.

Amaltheus bechteri Frentzen stad. nudum – Frentzen 1937: 106, pl. IV, fig. 32; pl. V, figs 4, 14; pl. IV, figs 3, 4, 7.

Pleuroceras solare – Howarth 1958: 28, pl. V, figs 1-7, 10. — Tintant et al. 1961: pl. I, fig. 5. — Bourdenet 1964: pl. 1, fig. 3. — Mattéi 1985: pl. XII, fig. 7. — Meister 1988: pl. 6, figs 6-11.

TYPE MATERIAL. — Ľe holotype is the specimen figured by Phillips (1829: 135, pl. 4, fig. 29) and is now presumed to be lost. Howarth (1958: 28, pl. V, fig. 1) specimen has been designated as neotype (Sedgwick Museum of Earth Sciences, SM. J44277 ).

SPECIMENS AVAILABLE. — UPMC-186, 190, 193-195.

STRATIGRAPHICAL DISTRIBUTION. — Late Pliensbachian, Spinatum chronozone , base of Apyrenum subchronozone up to the beginning of Hawskerense subchronozone. Haute-Marne: bed 8 or 13 to 16a.

GEOGRAPHIC DISTRIBUTION. — South-East France ( Monestier 1913, 1916, 1928; Mattéi 1985; Meister 1989; Morard 2004); eastern France, Burgundy ( Tintant et al. 1961; Lablanche et al. 1997), Franche-Comté ( Bourdenet 1964) and Haute-Marne (this work); North-West France, Paris Basin, Normandy ( Dommergues 2008); North-West Germany ( Jordan 1971); South-West Germany ( Frentzen 1934); South-East Germany (Hoffman et al. 2007); England ( Howarth 1958); Spain, Betic Range (Comas-Rengifo et al. 2010); Portugal ( Mouterde 1967); Italy, Lombardy Basin ( Wiendenmayer 1980); Morocco, Moyen-Atlas ( Morard 2004).

DESCRIPTION

Evolute shells with whorls slightly higher than large. Demarcation of ventro-lateral edge can occur late in the ontogeny and be slightly pronounced. Sometimes, small tubercles can be observed up to a diameter of 20 mm. Ribs are sharp-raised.

Figures

FIG. 5. — Amaltheus margaritatus Montfort, 1808:A, B, specimen UPMC-104, Outcrop 1, bed 3; E, F, specimen UPMC-147, Outcrop 1, bed 5. Amaltheus gibbosus (Schlotheim, 1820); I, J, specimen UPMC-148, Outcrop 1, bed 5; Amauroceras ferrugineum (Simpson, 1855); C, D, specimen UPMC-140, Outcrop 1, bed 3; G, H, specimen UPMC-139, Outcrop 1, bed 3. Amaltheus salebrosum Hyatt, 1867; K, L, specimen UPMC-225, Outcrop 1, bed 7. Pleuroceras transiens (Frentzen, 1937); M, O, specimen UPMC-174, Outcrop 1, beds 8, 9. Scale bars: 1 cm. The arrows indicate the beginning of the body chamber.

FIG. 7. — Pleuroceras spinatum (Bruguière, 1789): A, specimen UPMC-189, Outcrop 1, bed 13. Pleuroceras solare (Phillips, 1829); B, C, specimen UPMC-190, Outcrop 1, bed 13; D, E, specimen UPMC-200, Outcrop 1, bed 16. Pleuroceras solare trapezoidiforme (Maubeuge, 1951);F, G, specimen UPMC-202,Outcrop 1, bed 16. Pleuroceras cf. spinatum (Bruguière,1789);H, I, specimen UPMC- 201, Outcrop 1, bed 16. Scale bar: 1 cm. The arrows indicate the beginning of the body chamber.