taxonID	type	description	language	source
7C52D4FC8E9557729464E76E5420FDDA.taxon	description	Figs 3, 4, 5, 6, 7, 8	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
7C52D4FC8E9557729464E76E5420FDDA.taxon	materials_examined	Additional material. Ca. 240 juvenile shells (illustrated material SNSB-BSPG 2023 X 1 - 15). from the Eke Formation at Bodudd (S Gotland, Sweden, 57 ° 04 ' 05.8 " N, 18 ° 11 ' 34.7 " E, compare Calner et al. 2004, fig. 2) which is Ludfordian (Ludlow, upper Silurian) in age.	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
7C52D4FC8E9557729464E76E5420FDDA.taxon	materials_examined	Description of additional material from sieved bulk samples (juvenile and encrusted shells, Figs 6 - 8). Shell with tightly coiled ca. 1.5 - 2.5 initial whorls including protoconch and early teleoconch; largest shell studied with SEM 4.1 mm long, 1.9 mm wide; encrusted specimens (forming cores of oncoids) probably belonging to the present species up to 20 mm long; protoconch with round, convex whorls and slightly elevated spire, lacking ornament (but re-crystallized); encrusted (oncoid) specimens possibly belong to this species up to 20 mm long; diameter of first whorl 0.17 - 0.25 mm, diameter of protoconch 0.37 - 0.68 mm (two measurements); protoconch / teleoconch-transition indistinct due to preservation (re-crystallization) but apparent by sudden onset of co-marginal ribs (may also appear as frills or lamellae) and rapid increase of expansion rate of whorl diameter; later teleoconch detaches and becomes uncoiled, bent to slightly elongated, slowly increasing in diameter, forming a cap-shaped tube; teleoconch ornamented by sharp, narrow co-marginal ribs separated by wide interspaces; strength of ribs and density of ribbing variable; ribs can also form lamellae; ribs appear much longer (lamellae) in specimens studied in thin sections than ribs in specimens from bulk samples suggesting that such lamellar ribs broke off during processing of sample; teleoconch also ornamented by thin spiral lirae, much weaker than co-marginal ribs; shell having a calcitic layer as suggested by thin sections.	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
63E480A487FC513EB6B0F7E8ED9C5D97.taxon	description	Figs 9, 10, 11, 12	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
63E480A487FC513EB6B0F7E8ED9C5D97.taxon	materials_examined	Material. 6 specimens (SNSB-BSPG 2020 XCI 117 - 122) from the Finis Shale Member of the Graham Formation (late Pennsylvanian, Virgillian, North Central Texas, USA) at the locality TXV- 200: Lost Creek Lake emergency spillway at dam, approximately 4 km northeast of Jacksboro, Jack County, Texas on Texas Highway 59. AMNH Locality 5562, 33 ° 14 ' 11.17 " N, 98 ° 07 ' 11.33 " W, 33.230, - 98.136.	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
63E480A487FC513EB6B0F7E8ED9C5D97.taxon	description	Description. Shell limpet-shaped; protoconch (description largely based on SNSB-BSPG 2020 XCI 117, Figs 9 A, 12) with an initial bulb (Fig. 12 I) slightly elongated, 100 - 120 µm long, 70 - 75 µm wide, terminating in a slight constriction; width of initial bulb at 100 µm shell length 70 - 80 µm; shell after initial bulb forming a straight tube slowly increasing in width (Fig. 12 II); dextral coiling starts at 270 - 360 µm shell length and coiling comprises 100 - 180 ° (Fig. 12 III) until strong co-marginal ribs develop on the shell; the smooth initial shell has the form of a hook that encloses a central gap i. e., it is openly coiled; terminal width of whorl of initial smooth shell 0.5 - 0.6 mm; smooth initial whorl followed by rapidly expanding shell portion with strong collabral ribs (Fig. 12 IV); ribs separated by wider interspaces, prosocyrt in apical view and prosocline in lateral view; initial smooth shell part resting on axially ribbed shell; shell part with strong axial ribs has width of 0.8 - 1 mm at termination; shell distinctly and abruptly widening after initial shell with axial ribs resulting in a cap-shaped morphology (Fig. 12 V), transition at an angle; following shell cap-shaped with variable co-marginal ornament; one specimens shows fine longitudinal lirae on the teleoconch (Fig. 10 B 6).	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
63E480A487FC513EB6B0F7E8ED9C5D97.taxon	discussion	Discussion. Orthonychia parva is widely distributed throughout the Carboniferous of the US (Yochelson and Saunders 1967). It has also been reported from the Pennsylvanian of North Central Texas (Mineral Wells Fm.) (Plummer and Moore 1921) although not from the Finis Shale. To our knowledge, Knight (1934, figs 1 d-g) reported the only specimens (four) with preserved protoconchs. Two of these specimens were also illustrated in detail (SEM) by Bandel and Fryda (1999, pl. 2 figs 5 - 8): (reproduced by Fryda 2005, fig. 3 D; Fryda et al. 2008 a, fig. 10.8 E, G; Fryda 2012, fig. 14 E, M; Nuetzel 2014, fig. 14 E, H, erroneously as Pseudorthonychia). The same type of protoconch with stretched initial part and open coiling has been reported for the Devonian Praenatica cheloti by Fryda et al. (2009). The present shell displays considerable ontogenetic change. There can be little doubt that the initial bulb represents the embryonic shell as was also concluded by Bandel and Fryda (1999), Fryda et al. (2008 b), and Fryda (2012). Its small size of 100 - 120 µm x 70 µm suggests indirect, planktotrophic larval development. The question is at which stage the larval shell terminates and the teleoconch starts. Knight (1934) for the first time reported and described this type of protoconch and noticed its morphology which is unusual for gastropods (' curious vermiform nuclei'). He described the ' nucleus' as a narrow vermiform hook of one smooth revolution. The abrupt expansion of the shell which then bears co-marginal ribs was called by him ' neanic' i. e., as representing the early juvenile teleoconch. By contrast, based on the restudy of Knight's (1934) material from the Labette Shale, Bandel and Fryda (1999) and Fryda (2012) assumed that the axially ribbed part following the smooth hook-like shells belongs to the larval shell. Here, we follow Knight's (1934) interpretation because the smooth shell terminates abruptly and the size of the following axially ribbed portion of the shell (here Fig. 12 IV) has a width of ca. 2 mm at its termination which is too large for a larval shell. Hence the larval shell of O. parva comprises portions I-III as given in Fig. 12. The change from a straight narrow tube to a coiled tube (Fig. 12 II to III) is readily explained: it would be highly disadvantageous for the pediveliger to settle with an entirely straight narrow tube (stretched, uncoiled shell tube would probably be vulnerable and hinder locomotion) and therefore coiling in the last period of larval life does make sense as a preparation for benthic life. The early axially ribbed teleoconch was probably formed by the crawling juvenile and the sudden widening of the shell could indicate the start of the sedentary life on crinoids.	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
F47976FB9D855B8CA78608AB0AAF11E6.taxon	description	Fig. 13 A, B	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
F47976FB9D855B8CA78608AB0AAF11E6.taxon	materials_examined	Material. Two specimens from the Upper Mississippian (Chesterian) Imo Formation, Arkansas (SNSB-BSPG 2023 I 89, SNSB-BSPG 2023 I 90). The material was sampled by R. H. Mapes (ARC- 02, samples Imo- 6 and Imo- 8.) at the Location # 1 as given by Jeffery et al. (1994), figs 1 and 2). This location, the Peyton Creek Roadcut, was also described in detail by Manger (1977) who measured a section in the outcrop (Manger 1977, fig. 1). The sample Imo- 6 sample came from position 20 in this section, approximately 110 feet above the base of his measured section and the Imo- 8 sample came from position 24, which is about 135 feet above the base of his measured section. NE 1 / 4 sec. 11 and NW 1 / 4 sec. 12, T. 13 N., R. 15 W. Van Buren County, Arkansas	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
F47976FB9D855B8CA78608AB0AAF11E6.taxon	description	Description. Juvenile shell 0.66 mm wide, 0.52 mm high; shell starts with a slightly elongated initial bulb with a length of 87 µm and a width of 63 µm; width of shell at shell length 100 µm is 66 - 68 µm; initial bulb is bent slightly adapically in relation to the following straight shell-tube; following shell is an entirely straight, smooth tube that increases slowly in diameter. At a total shell length of 320 µm the tube starts a sharp coiling in a dextral direction and at the same time, it is strongly expanding in diameter; shell is smooth except of a faint micro-striation visible on the coiled part of the first whorl.	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
F4E29B18A8415F0083385677AF802DA5.taxon	description	Fig. 2	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
F4E29B18A8415F0083385677AF802DA5.taxon	materials_examined	Material. Only the holotype (PMU 37146) is known, from the Late Ordovician (Katian) Boda Limestone at Jutjaern quarry, Siljan district, Dalarna.	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
F4E29B18A8415F0083385677AF802DA5.taxon	diagnosis	Diagnosis. Shell tall, teleoconch forming a weakly cyrtoconic tube, open coiled with apex coiled through half a whorl; supra-apical surface formed by raised and convex median section; teleoconch ornamentation consist of densely spaced, slightly undulating, strong co-marginal ribs on initial parts, widening later in ontogeny to distinct growth increments that end in a flared lamellae; growth lines corrugated, laterally forming two or three spaced flutes, across the median part only weakly undulating; last part of protoconch without visible ornament and abrupt transition to teleoconch; early protoconch whorls poorly preserved as imprint, possibly tightly coiled consisting of ca. two whorls.	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
F4E29B18A8415F0083385677AF802DA5.taxon	description	Description. Shell tall, weakly cyrtoconic, open coiled with apex coiled through at least half a whorl before shell coiling ends and a straight tube forms, widening gradually with length at base about 45 % of total height (= 20 mm). Shell nearly planispiral but with weak translation down the axis if viewed with aperture in normal right-handed position. Apex overhang sub-apical margin. Supra-apical surface of shell forms a raised and convex median section, with concave transition to lateral surfaces. Ornamentation on initial conch consist of densely spaced, slightly undulating, strong co-marginal ribs. A couple of millimeters from the apex, the space between the ribs widens gradually and distinct growth increments (here taken as the growth accumulated in the space between subsequent lamellae) become apparent. Increments are spaced no more than 1 mm apart, consist of fine co-marginal growth lines and end with a lamella that extends prominently and nearly horizontal from the shell (arrows in Fig. 2 A 4, A 5). Near the aperture the space between the increments again becomes narrower. The growth lines are corrugated, laterally forming two or three spaced flutes that have a pointed bell-shaped, whereas the growth lines across the median part only are weakly undulating. Ornamentation on inner margin obscured by matrix. Medially the growth-lines form a broad low-relief U-shape. Last part of protoconch without visible ornament and abrupt transition to teleoconch; width of last protoconch whorl at termination about 200 µm; early protoconch whorls poorly preserved as imprint, possibly tightly coiled consisting of ca. two whorls.	en	Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H., Cook, Alex G. (2023): On Paleozoic platycerate gastropods. Zitteliana 97: 29-51, DOI: http://dx.doi.org/10.3897/zitteliana.97.115688, URL: http://dx.doi.org/10.3897/zitteliana.97.115688
