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Fig. 2 in Variability of conch morphology in a cephalopod species from the Cambrian to Ordovician transition strata of Siberia

Fig. 2. Exposure of the source strata for the blocks with nautiloids found a few kilometers upstream the Angara River. A. Transition from the Ust-kut to Iya Formation. B. Top of the limestone succession of the Ust-kut Formation. C. Columnar stromatolite and limestone of the Ust-kut Formation. D. Field sketch of the section showing position of conodont samples and probable correspondence between the strata exposed and the loose blocks.

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Fig. 3 in Variability of conch morphology in a cephalopod species from the Cambrian to Ordovician transition strata of Siberia

Fig. 3. Conodonts from the probably latest Furongian Ust-kut Formation from the exposure at Pashino on the Angara River, Siberia, Russia, samples Ang-4, block No. 1 (A–E; Fig. 1) and Ang-1, topmost limestone layer (F–N; Fig. 2B). A, K–N. Utahconus(?) eurypterus (Abaimova, 1971), ZPAL N. IV/163, 168, 169, 170, and 172, respectively. B–J. Laurentoscandodus triangularis (Furnish, 1938), ZPAL N. IV/165, 166, 167, 173, 174, 175, 177, and 176, respectively; in posterior views, except for medial view in L1 and occlusals view in M1 and N2. Tentative identification of elements locations indicated S, S0, M, P.

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Fig. 4 in Variability of conch morphology in a cephalopod species from the Cambrian to Ordovician transition strata of Siberia

Fig. 4. Benthic bellerophontid and monoplacophoran molluscs from the probably latest Furongian Ust-kut Formation from the exposure at Pashino on the Angara River, Siberia, Russia; samples Ang-4, block No. 1 (A, B, D) and Ang-1, topmost limestone bed (C, E–I). A, B. Sinuitopsis sp. nov., ZPAL N. IV/154 and 155, in external (A1, B1) and lateral (A2, B2) views. C. Bellerophontid gen. et sp. nov. ZPAL N. IV/156, in lateral (C1) and external (C2) views. D. Hypseloconid ZPAL N. IV/157, in anterior (D1) and lateral (D2) views. E. Monoplacophoran? ZPAL N. IV/158, in dorsal (E1) and lateral (E2) views. F–I. Phosphatised conchs of juvenile individuals probably representing the same species as that on C; ZPAL NIV/162, 161, 160, and 159, respectively, in lateral (F1, H, and I) and apertural (F2, G) views.

Fig. 3 in A revaluation of rhipidocystid echinoderms based on a new flattened blastozoan from the Upper Ordovician of Maryland, USA

Fig. 3. Rhipidocystid echinoderm Durhamicystis americana gen. et sp. nov. from the Upper Ordovician Chambersburg Formation, Maryland, USA. A. USNM 642510. B. USNM 642511a, b. Photographs of specimens submerged in water to increase contrast of plates and plate boundaries (A1, B1). Camera lucida drawings indicating plate arrangements (A2, B2). Abbreviations: FP, flooring plate (green); G, gonopore; H, hydropore; M1–M9, marginal plates (yellow); O1–O7, oral plates (red); Pe, periproct. Central plates colored in blue, stem in purple, and brachioles in brown.

Fig. 6 in A revaluation of rhipidocystid echinoderms based on a new flattened blastozoan from the Upper Ordovician of Maryland, USA

Fig. 6. Comparisson between the rhipidocystids Mandalacystis dockery Lewis, Sprinkle, Bailey, Moffit, and Parsley, 1987 (A), Petalocystites ikecanensis (Sprinkle, 1973) (B), Neorhipidocystis norvegica (Bockelie, 1981) (C), and Durhamicystis americana gen. et sp. nov. (D). Abbreviations: FP, flooring plate (green); M1–M9, marginal plates (yellow); O1–O7, oral plates (red); central plates (blue); stem (purple), brachioles (brown); Pe, periproct. Based on Lewis et al. 1987 (A), Sprinkle 1973 (B), and Bockelie 1981 (C).

Fig. 1 in A revaluation of rhipidocystid echinoderms based on a new flattened blastozoan from the Upper Ordovician of Maryland, USA

Fig. 1. Rhipidocystid echinoderm Durhamicystis americana gen. et sp. nov. from the Upper Ordovician Chambersburg Formation, Maryland, USA. A. Holotype USNM 642510 showing the theca, proximal stem, and brachioles; general view of the complete specimen in ventral view (A1), detail of oral area and proximal part of the brachioles (A2), specimen in lateral view showing the periproct surrounded by three plates (A3). B. Paratype USNM 642513; general view of the complete specimen in ventral view (B1), note central plates in thecal interior, and single columnal attached to basals; detail of the anal pyramid on left edge (B2). Specimens whitened with ammonium chloride sublimate.

Fig. 4 in A revaluation of rhipidocystid echinoderms based on a new flattened blastozoan from the Upper Ordovician of Maryland, USA

Fig. 4. Rhipidocystid echinoderm Neorhipidocystis norvegica (Bockelie, 1981) from the Late Ordovician of the Oslo Region, Norway. A. PMO 101.143, half complete specimen; detail of the oral area (A2). B. PMO 101.144 (holotype), almost complete specimen lacking the lower portion; detail of the oral area (B2), note V-shaped notches and cover plates on uniserial brachioles. Specimens are latex casts whitened with ammonium chloride sublimate. Scale bars 5 mm.

Fig. 5 in A revaluation of rhipidocystid echinoderms based on a new flattened blastozoan from the Upper Ordovician of Maryland, USA

Fig. 5. Camera lucida drawings and plate interpretations of the oral area in Neorhipidocystis norvegica (Bockelie, 1981). A. PMO 101.143. B. PMO 101.144, holotype. Abbreviations: CP, cover plates over ambulacra and brachioles; FP, flooring plates; G, gonopore; H, hydropore; M, marginal plates; O1–O6, oral plates.

Fig. 2 in A revaluation of rhipidocystid echinoderms based on a new flattened blastozoan from the Upper Ordovician of Maryland, USA

Fig. 2. Rhipidocystid echinoderm Durhamicystis americana gen. et sp. nov. from the Upper Ordovician Chambersburg Formation, Maryland, USA. A. Paratype USNM 642511a, b; general view showing two nearly complete superimposed specimens (A1); detail of the oral area, proximal brachioles attached to marginal, oral, and floor plates, and three apertures (periproct, hydropore slit, and tiny gonopore) (A2); specimen in left lateral view showing the thin central plates from both integuments (A3); specimen in right lateral view showing the position of the periproct (A4); detail of facets between brachiolar plates and cryptic vertical sutures indicated by arrows (A5); detail showing thin internal projections of weathered, U-shaped, marginal plates (A6). Specimens whitened with ammonium chloride sublimate.

Fig. 8 in Early ontogenetic growth stages of Middle Ordovician orthoceratoid cephalopods from Bohemia

Fig. 8. Box-plot of diameter of initial chambers of Ordovician orthoceratoid cephalopods. Data from Ruedemann (1912), Balashov (1957), Evans (2005, 2007), Aubrechtová (2015), Kröger (2006, 2007), and Kröger et al. (2009).

Fig. 5 in Early ontogenetic growth stages of Middle Ordovician orthoceratoid cephalopods from Bohemia

Fig. 5. Drawings of known embryonic shells with initial chambers of Ordovician orthoceratoids (cf. Kröger and Mapes 2007: fig. 4 and Klug et al. 2015: fig. 1.3.). Dotted lines indicate the assumed position of the siphuncle in Arionoceras? sp. and Orthoceratida indet. sp. 2. In Orthoceratida indet. sp. 2, note a sketch of hyposeptal cameral deposits (see the text below and Fig. 7C1). The stratigraphic position of Bactroceras angustisiphonatum and Arionoceras? sp. is either uppermost Lower Ordovician, or lowermost Middle Ordovician (David Evans, personal communication 2019; see also Evans 2005 and 2007). Orthoceratidae gen. et sp. indet B (Kröger 2007) is likely to be conspecific with Transorthoceras osmundsbergense according to Kröger et al. (2011a).

Fig. 6 in Early ontogenetic growth stages of Middle Ordovician orthoceratoid cephalopods from Bohemia

Fig. 6. Apical and juvenile shell parts of orthoceratid cephalopods; Middle Ordovician, Darriwilian Stage, Šárka and Dobrotivá formations, Czech Republic. A. Bactroceras sandbergeri (Barrande, 1867), MWB S 06823, Volduchy, third phragmocone chamber (estimated based on shell diameter) and adjacent part of body chamber. B. Orthoceratida indet. sp. 4, MWB S 06827, Volduchy, counterpart of initial chamber and adjacent part of phragmocone and one corroded phragmocone septum; note longitudinal striae. C. Orthoceratida indet sp. 5, NM L 59872, Malé Přílepy, counterpart (C1), latext cast C2); note longitudinal striae.

Fig. 3 in Early ontogenetic growth stages of Middle Ordovician orthoceratoid cephalopods from Bohemia

Fig. 3. Apical shell of the orthoceratoid Bactroceras sandbergeri (Barrande, 1867); Middle Ordovician, lower Darriwilian Stage, Šárka Formation, Czech Republic. A. MWB S 06761, Mýto-Svatoštěpánský rybník, latex cast of one of counterparts in lateral view, note fine, obliquely transverse surface ornamentation. B. MWB S 06762, Mýto-Svatoštěpánský rybník, counterpart (B1) and its latex cast (B2), in lateral view (initial chamber bent towards dorsum). C. MWB S 06763, Rokycany-Díly, internal mould in lateral view, single (adoralmost) phragmocone chamber showing ventrally situated siphuncle (C1), latex cast of the second counterpart (C2).

Fig. 2 in Early ontogenetic growth stages of Middle Ordovician orthoceratoid cephalopods from Bohemia

Fig. 2. Apical shell parts of the orthoceratoid Bactroceras sandbergeri (Barrande, 1867), Middle Ordovician, lower Darriwilian Stage, Šárka Formation, Czech Republic. A. MWB S 06759, Rokycany-Díly, internal mould in ventral view (A1), with accompanying trilobite Ormatops sp., brachiopod Euorthisina sp., and indeterminate hyolith; detail (A2), note the decrease of apical angle at second phragmocone chamber; latex cast of counterpart in ventral view (A3). B. MWB S 06764, Těškov, internal mould in lateral view, venter on right hand-side (initial chamber bent towards dorsum), initial and second phragmocone chamber preserved as counterpart. C. MWB S 06760, Těškov, latex casts of both sides of counterparts (C1, C2), note suspicious surface structures. D. NM L 59577, Praha-Hanspaulka, latex cast of counterpart.

Fig. 1 in Early ontogenetic growth stages of Middle Ordovician orthoceratoid cephalopods from Bohemia

Fig. 1. Position of Ordovician rocks of the Prague Basin within the Bohemian Massif and the localities from which the herein studied specimens originate see the text below). 1, Praha-Šárka cihelna (brickyard); 2, Praha-Šárka; 3, Praha-Hanspaulka; 4, Malé Přílepy; 5, Lhotka u Berouna; 6, Těškov; 7, MýtoSvatoštěpánský rybník; 8, Rokycany-Díly; 9, Volduchy. Adapted after Manda (2008).

Fig. 2 in Conulariids from the Lower Ordovician of the southern Montagne Noire, France

Fig. 2. Stratigraphic range of conulariids in the Lower Ordovician of the southern Montagne Noire. Stratigraphic column redrawn and modified from Courtessole et al. (1983). Stratigraphy based on Vizcaïno et al. (2001), Álvaro and Vizcaïno (2003), Tortello et al. (2006), and Serpagli et al. (2007).

Fig. 3 in Conulariids from the Lower Ordovician of the southern Montagne Noire, France

Fig. 3. Conulariid scyphozoan Archaeoconularia cf. insignis (Barrande, 1867), Landeyran Formation, upper Floian, Lower Ordovician; southern Montagne Noire, France. Specimens oriented with the apertural end directed toward the top of the page; arrows in A1 and B1 point to a facial midline. A. The two exposed faces of the part of the most complete specimen (MNHN.F.A71851a), which terminates in a crumpled schott (A1). Detail of the part, arrow pointing to the crumpled terminal schott (A2). B. The counterpart of the specimen in A (MNHN.F.A71851b) (B1). Detail of the apertural region of the counterpart, showing the fine ornament including some of the most clearly defined nodes (arrows) (B2).

Fig. 1 in Conulariids from the Lower Ordovician of the southern Montagne Noire, France

Fig. 1. Geology of the Montagne Noire with conulariid localities. A. Geologic sketch of the Montagne Noire. B. Geologic sketch of France showing the pre-Hercynian rocks and the location of the Montagne Noire (rectangle). C. Simplified geological map of the Minervois and Pardailhan nappes, southern Montagne Noire, with the four main areas yielding Lower Ordovician conulariids (dashed square boxes); 1, western Minervois area, Aude (ruisseau des Lavandières, vallée de l'Ourdivieille); 2, eastern Minervois area, Aude (Brama, vallée du Merlaux); 3, western Saint-Chinianais area, Hérault (Canimals, Donnadieu, Saint-Cels); 4, eastern Saint-Chinianais area, Hérault (Pech Tavernier, les Rocs Nègres, la Rouvelane, les Sources du Foulon). Maps redrawn and modified from Guérangé-Lozes and Burg (1990) and Álvaro and Vizcaïno (2001).

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FIGURE 1 in Putative Ordovician green alga Krejciella reinterpreted as enteropneust hemichordate tube (Czech Republic)

FIGURE 1. Location map of the study area, showing the location of each of the studied localities within the Ordovician of the Prague Basin. A. Map of the Czech Republic and the Bohemian Massif showing the distribution of Ordovician rocks in the Prague Basin. B. Ordovician of the Prague Basin with the location of five outcrops that yielded the studied specimens.