Oecoptychius refractus ( Reinecke, 1818 )

Jain, Sreepat, Salamon, Mariusz A., Schweigert, Günter & Płachno, Bartosz J., 2023, Morphological variations and geographic distribution of the rare Middle Jurassic ammonite Oecoptychius refractus, Acta Palaeontologica Polonica 68 (2), pp. 321-335 : 327-331

publication ID	https://doi.org/ 10.4202/app.01026.2022
persistent identifier	https://treatment.plazi.org/id/039487B7-FFE2-F40C-FCFC-E829FAD64FE9
treatment provided by	Felipe
scientific name	Oecoptychius refractus ( Reinecke, 1818 )
status

Treatment

Oecoptychius refractus ( Reinecke, 1818)

Figs. 4–10 View Fig View Fig View Fig View Fig View Fig View Fig .

1818 Nautilus refractus ; Reinecke 1818: fig. 27‒30.

1830 Ammonites refractus Reinecke ; Zieten 1830: 14, pl. 10: 9.

1846 Ammonites refractus Reinecke ; Quenstedt 1846: 150, pl. 11: 12.

1857 Ammonites refractus ; Quenstedt 1857: 524, pl. 69: 25, 26, 28‒30.

1878 Oecoptychius refractus ; Neumayr 1878: 73.

1887 Ammonites refractus ; Quenstedt 1887: 762 f, pl. 86: 37‒50.

1887 Oecoptychius refractus Quenstedt ; Zakrzewski 1887: 122, pl. 1: 3.

1897 Oecoptychius refractus Haan ; Glangeaud 1897: 104, pl. 3: 7‒10.

1908 Ammonites (Oecoptychius) refractus Reinecke sp.; Engel 1908: pl. 4: 6.

1924 Oecoptychius refractus Haan ; Roman and Debrun 1924: 106, pl.

11: 5. 1928 Oecoptychius refractus Haan ; Sayn and Roman 1928: 150, pl. 10:

12. 1928 Oecoptychius refractus (Reinecke) ; Spath 1928: 278, pl. 81: 5. 1932 Oecoptychius refractus Reinecke ; Corroy 1932: 120, pl. 10:

10‒11. 1952 Oecoptychius refractus (Haan) ; Makowski 1952: 31, pl. 3: 3. 1958 Oecoptychius refractus Reinecke ; Collignon 1958: 28, fig. 115. 1985 Oecoptychius refractus (Reinecke) ; Schlegelmilch 1985: 137, pl.

54: 4.

1987 Oecoptychius refractus (Reinecke) ; Callomon et al. 1987: 26, pl. 3: 7.

1994 Oecoptychius refractus (Reinecke) ; Fischer 1994: 153, pl. 60: 2.

1998 Oecoptychius refractus (Reinecke) ; Schweigert and Dietze 1998: pls. 6: 5, 8: 5, 9: 4‒11.

Type material: Lectotype: NMC 52 /1, original of Reinecke (1818: fig.

29), designated by Zeiss in Heller and Zeiss (1972). Paralectotype:

NMC 52/2, original of Reinecke (1818: fig. 27) (see Schweigert and

Dietze 1998).

Type locality: Probably eastern Franconian Alb (area of Trockau) (for further details, see Schweigert and Dietze 1998) .

Fig. 7. Biozonation and morphological variation in Oecoptychius refractus ( Reinecke, 1818) [m]. A. Biozonation used in the present study with the → occurrence of O. refractus ( Reinecke, 1818) noted in Kachchh (western India; Spath 1928), Poland ( Makowski 1952), and Madagascar ( Collignon 1958). B. Morphological variation in O. refractus ( Reinecke, 1818) [m]. A, GIUS 8-3657/9; B, GIUS 8-3657/9; C, GIUS 8-3657/8; D, GIUS 8-3657/6;

E, GIUS 8-3657/12; F, GIUS 8-3657/4; G, GIUS 8-3657/5; H, GIUS 8-3657/3; I, GIUS 8-3657/11; J, GIUS 8-3657/10; K, GIUS 8-3657/7; L, specimen of Makowski (1952: 31, pl. 3: 3; no mention of specimen number); M, GIUS 8-3657/2; N to AD, SMNS 70655/1–17, respectively.

Type horizon: Erymnoceras coronatum Zone , middle Callovian, Middle Jurassic.

Measurements.—See Table 1.

Description.—The inner and the early part of the middle whorls not visible in any of the studied specimens. The middle and outer whorls are characterized by: (i) primaries long and sharp, bifurcate at mid- to outer third of whorl height into two forwardly inclined equally sharp secondaries, (ii) straight primaries arising from the rounded umbilical margin, (iii) with increasing shell diameter, the rounded umbilical region developing a smooth area; hence, with secondaries only visible at the outer third of whorl height, (iv) a distinct kink in the body-chamber, i.e., at larger shell sizes (on the phragmocone and in front of the body-chamber kink, in the case of a mold), a ventral groove (furrow) is noted, (v) morphological variation in the shape of the body-chamber with agradation from V- to U-shape in longitudinal section (Fig. 7).

In specimens preserved with the shell especially in the area of the body-chamber, and rarely on the phragmocone, a strigoceratid spiral striation is present (see Schweigert and Dietze 1998: pls. 6: 5; 9: 8, 9). A specimen with remains of the shell with striation, from the Ornatenton Formation ( Kosmoceras jason Zone ) of Neidlingen, SW Germany is illustrated ( Fig. 8 View Fig ). Even if the shell is preserved, it often remains in the surrounding rock matrix and only the molds lacking the shell are collected. On molds, the spiral striae are occasionally discernible in large specimens; none of the present specimens (Dmax = 21 mm) preserve this feature. In rare cases when the shell is preserved, a smooth band is also observed which, like the furrow, dissapears at the end of the body-chamber.

The upper Callovian specimens from Poland are more similar to the lectotype by means of the dimension pa- rameters (more evolute and compressed; average U/D = 0.05; T/H = 1.44, respectively) and form a separate grouping when compared to the much larger middle Callovian French specimens ( Fig. 9 View Fig , Table 1). The whorl thickness versus coiling ratio also displays separate grouping ( Fig. 9D View Fig , Table 1) .

Remarks.— Oecoptychius grossouvrei Brasil, 1894 ( Parkinsoni Zone , upper Bajocian, Middle Jurassic; see also Schweigert and Dietze 1998: 22, pl. 1: 3) is morphologically close to Oecoptychius refractus ( Reinecke, 1818) described herein, but lacks the distinctive body-chamber kink, has a somewhat oval-shaped body-chamber and finer secondaries restricted to the outer third of the whorl height.

Oecoptychius subrefractus ( Buckman, 1920) ( Morphoceras macrescens Subzone View in CoL , Zigzagiceras zigzag Zone , lower Bathonian, Middle Jurassic; see also Dietl 1986; Dietze et al. 1997; Schweigert and Dietze 1998) has a similar but somewhat less developed body-chamber kink ( Schweigert and Dietze 1998: 22, pl. 1: 3); it is also relatively compressed and evolute ( Fig. 9 View Fig , Table 1) and with a finer ornamentation.

Oecoptychius globosus Schweigert and Dietze, 1998 ( Proplanulites koenigi Zone , lower Callovian; original of Quenstedt 1886: pl. 86: 51) is a very large form (27 mm shell diameter, Couffon 1919; see Table 1) but resembles O. refractus in having the mid-ventral furrow, primaries splitting into two ribs and the smooth umbilical region but lacks the characteristic and pronounced body-chamber kink; the mid-ventral furrow is less developed in O. globosus (see Schweigert and Dietze 1998: pl. 4: 6‒7).

In terms of dimensional proportions (whorl thickness vs. coiling ratio; Fig. 10 View Fig ), the O. grossouvrei ( Parkinsonia parkinsoni Zone View in CoL , upper Bajocian) falls within the O. refractus range, whereas both the O. subrefractus ( Zigzagiceras zigzag Zone , lower Bathonian) and O. globosus ( P. koenigi Zone , lower Callovian) are outliers ( Fig. 10 View Fig ) and morphologically quite different ( Schweigert and Dietze 1998).

Stratigraphic and geographic range.— Kosmoceras jason Zone (middle Callovian) to Quenstedtoceras lamberti Zone (upper Callovian); Poland (middle and upper Callovian; the latter is from this study), Germany (middle Callovian), France (middle and upper Callovian), Madagascar (middle Callovian), Kachchh (upper Callovian).

SMNS	Staatliches Museum fuer Naturkund Stuttgart

Copyright notice

No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.

Taxonomy

Kingdom	Animalia
Phylum	Mollusca
Class	Cephalopoda
Family	Oecoptychiidae
Genus	Oecoptychius