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Figure 1. A in Early Silurian phacopide trilobites from central Victoria, Australia

Figure 1. A, map of south-eastern Australia; approximate area of fig. 1B is indicated by a rectangle. B, map of central Victoria showing localities cited in the text; the areas covered by maps in figs. 4 and 9 are indicated.

Fig. 5 in A new genus of Late Ordovician-Early Silurian pentameride brachiopods and its phylogenetic relationships

Fig. 5. Transverse serial sections of two paratype specimens of Parastrophina portentosa (Nikitin and Popov in Nikitin et al. 1996), Upper Ordovician, Dulankara Regional Stage, sample F−1014, Sortan−Manai, northern Betpak−Dala desert, Central Kazakhstan. A. NMW 98.28G.383, juvenile specimen. B. NMW 98.28G.377. Numbers indicate distances from apex.

Fig. 3 in A new genus of Late Ordovician-Early Silurian pentameride brachiopods and its phylogenetic relationships

Fig. 3. Sketches of selected serial sections of Protanastrophia repanda gen. et sp. nov. ROM 57738, paratype, Attawapiskat Formation, locality AK2c, Akimiski Island, Nunavut, Canada. Numbers denote distance from apex.

Fig. 6 in A new genus of Late Ordovician-Early Silurian pentameride brachiopods and its phylogenetic relationships

Fig. 6. Stratigraphic ranges and inferred phylogenetic relationships of 19 parastrophinid species and other selected syntrophiidine species based on one of six equally parsimonious cladograms (A) and emended topography of the Parastrophina cluster shown in strict consensus tree (B). Numbered nodes are supported by the character states listed in Appendix 3.

Fig. 2 in A new genus of Late Ordovician-Early Silurian pentameride brachiopods and its phylogenetic relationships

Fig. 2. Shell measurements of Protanastrophia repanda gen. et sp. nov. Sample AK2c, Attawapiskat Formation, Akimiski Island, Hudson Bay region, Nunavut, Canada.

Fig. 4 in A new genus of Late Ordovician-Early Silurian pentameride brachiopods and its phylogenetic relationships

Fig. 4. Pentameride brachiopod Parastrophina portentosa (Nikitin and Popov in Nikitin et al. 1996), Upper Ordovician, Dulankara Regional Stage, sample F−1014, Sortan−Manai, northern Betpak−Dala desert, Central Kazakhstan. A. NMW 98.28G.351, paratype, dorsal (A1), ventral (A2), anterior (A3), and lateral (A4) views of asymmetrical shell. B. NMW 98.28G.352, paratype, dorsal (B1), ventral (B2), lateral (B3), and anterior (B4) views. C. NMW 98.28G.353, paratype, lateral (C1) and anterior (C2) views of smooth, asymmetrical shell. D. NMW 98.28G.354, paratype, dorsal (D1), ventral (D2), lateral (D3), and anterior (D4) views of asymmetrical, juvenile shell.

Fig. 1 in A new genus of Late Ordovician-Early Silurian pentameride brachiopods and its phylogenetic relationships

Fig. 1. Pentameride brachiopod Protanastrophia repanda gen. et sp. nov.; Attawapiskat Formation, uppermost Telychian, Akimiski Island, Hudson Bay region, Nunavut, Canada. A. ROM 57734, holotype, dorsal (A1), ventral (A2), lateral (A3), posterior (A4), and anterior (A5) views. B. ROM 57735, paratype, dorsal (B1), ventral (B2), lateral (B3), posterior (B4), and anterior (B5) views of strongly asymmetrical, anteriorly costate shell. C. ROM 57736, paratype, dorsal (C1), ventral (C2), lateral (C3), posterior (C4), and anterior (C5) views of asymmetrical shell without costae. D. ROM 57737, paratype, dorsal (D1), ventral (D2), lateral (D3), posterior (D4), and anterior (D5) views of relatively small, largely symmetrical shell. E. ROM 57738, paratype, micrograph of transverse serial section, showing low ventral median septum, broad V−shaped spondylium, smooth alate plates, and discrete inner hinge plates, 0.7 mm from apex (refer to Fig. 3).

opencc-by-4.0Oct 2013View details →

Fig. 2 in A new early Silurian prioniodontid conodont with three P elements from Iran and associated species

Fig. 2. Distribution of conodonts in strata exposed on Hill B, for details see Männik et al. (2013). Arrows below and above the log indicate that the section continues in both directions. Samples: location and number of sample (total number of specimens in a sample), only productive samples are indicated. Taxa in bold are described in this paper, arrow at the upper end of distribution line of Oulodus spp. indicates that this taxon also occurs in higher strata. Conodont zones modified from Cramer et al. (2011), grey boxes indicate zones which were recognised in the studied section. Abbreviations: a., amorphognathoides; R., Rhuddanian.

opencc-by-4.0Oct 2013View details →

Fig. 1. A in A new early Silurian prioniodontid conodont with three P elements from Iran and associated species

Fig. 1. A. Location of the study area in East Central Iran (asterisk). B. Studied area in the Derenjal Mountains (open frame indicates location of studied sections).

Fig. 6 in Mat-forming coccoid cyanobacteria from early Silurian marine deposits of Sudetes, Poland

Fig. 6. Schematic drawing showing examples of vegetative cells of different age and baeocytes formation in modern colonial coccoid cyanobacteria. A. Stanieria sphaerica (Setchell and Gardner) Komárek and Anagnostidis 1986, scheme of baeocytes formation (after Komárek and Anagnostidis 1998). B–E. Stanieria cf. cyanosphaera (Komárek and Hindák) Komárek and Anagnostidis 1986, modern coccoid cyanobacteria grown in culture under irradiance level 20 µmol m–2 sec–1 at 22 (~0.5)oC. B. Cells of different age. C. Vegetative cells of different age. D. Baeocytes differentiation. · · E. Baeocytes liberation. After Komárek and Hindák from Silva and Pienaar 2000, modified. F. Chroococcidiopsis kashayi Friedmann 1961, various stage of baeocytic cell division (multiple fission), after Komárek and Anagnostidis 1998 modified. G. Fragment of early Silurian coccoid cyanobacterial mat. ZPAL Cy.1 GBŻ 49/1−4. Scale bars 20 µm.

Fig. 7 in Mat-forming coccoid cyanobacteria from early Silurian marine deposits of Sudetes, Poland

Fig. 7. Comparison of early Silurian coccoid cyanobacteria (left) from radiolarian cherts exposed at the Żdanów road−cut (Bardzkie Mountains) and modern coccoid cyanobacteria (right), all optical micrographs. A, C, E. Examples of cells of early Silurian Stanieria−like cyanobacteria at different stage of cell fission filled with minute reproductive cells (baeocytes). E. Optical micrographs with Nomarski illumination. A, C, E, ZPAL Cy.1 GBŻ 49/1−4. B, D, F. Mass culture of Stanieria cf. cyanosphaera (Komárek and Hindák) Komárek and Anagnostidis 1986, grown under irradiance level 20 µmol m–2 sec–1 at 22 · · (~0.5)oC, revealing spherical cells of varying size; some cells are filled with baeocytes (from Silva and Pienaar 2000, with publisher permission http://www.schweizerbart.de).

Fig. 3 in Mat-forming coccoid cyanobacteria from early Silurian marine deposits of Sudetes, Poland

Fig. 3. Optical micrographs of early Silurian radiolarian cherts from Żdanów in horizontal thin sections. A. Three globular aggregates of coccoid cyanobacteria forming mats visible in amorphous organic background. B–D. Magnified aggregates of variously degraded coccoid cyanobacteria showing different size of cells and mucilage sheaths. Some cells are filled with granular material resembling reproductive cells (baeocytes) of modern coccoid cyanobacteria. E, F. Magnified fragment of cyanobacterial colony (aggregate), partly degraded, showing individual cells. F. Optical micrographs with Nomarski illumination. All ZPAL Cy.1 GBŻ 49/1−4.

Fig. 2 in Mat-forming coccoid cyanobacteria from early Silurian marine deposits of Sudetes, Poland

Fig. 2. Optical micrographs of Early Silurian radiolarian cherts from Żdanów in vertical thin sections. A–C. Sections of black radiolarian chert in different magnifications showing well−defined laminae of organic matter composed of coccoid cyanobacterial biomass. D. A fragment of dense organic lamina, in which no details are visible. E, F. Magnified fragment of organic laminae composed of partly degraded and compacted aggregates of coccoid cyanobacteria, some capsule−like remnants of mucilage sheaths remaind uncompacted. A–C, ZPAL Cy.1 GBŻ 49/1–4; D, ZPAL Cy.1 GBŻ 16/2; E, F, ZPAL Cy.1 GBŻ 23/1.

Fig. 1 in Mat-forming coccoid cyanobacteria from early Silurian marine deposits of Sudetes, Poland

Fig. 1. Geological map of the northern part of the Bardzkie Mountains (Sudetes, southwestern Poland) and stratigraphic section of the Early Palaeozoic deposits at the Żdanów road−cut (after Porębska 1982, and Wyżga 1987; modified).

Fig. 8 in Mat-forming coccoid cyanobacteria from early Silurian marine deposits of Sudetes, Poland

Fig. 8. Diagram showing effect of compaction of a coccoid cyanobacterial aggregate. A–C. 3D aggregate without compaction (A) and under different degree of compaction. D–G. Axial vertical section of the same aggregate without compaction (D) and under different degree of compaction; note that in G outlines of cells and/or capsules are no more identifiable. Not to scale.

Fig. 5 in Mat-forming coccoid cyanobacteria from early Silurian marine deposits of Sudetes, Poland

Fig. 5. Scanning electron microscope (SEM) image of early Silurian subspherical aggregate of benthic coccoid cyanobacteria from Żdanów in horizontal thin section (sample IV–VI 49), showing HF−etched pattern with extending parts representing silicified common mucilage sheats (glycocalyx) and pits representing decomposed cells.

publicSep 2019View details →

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Data from: Early Silurian recovery of Baltica crinoids following the end-Ordovician extinctions (Llandovery, Estonia)

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Data from: Late Ordovician and Early Silurian virgianid and stricklandioid brachiopods from North Greenland: Implications for a warm-water faunal province

An unusually rich and diverse suite of virgianid brachiopods, hitherto poorly known, are systematically described here for the first time from the Ordovician–Silurian boundary interval (late Katian–Aeronian) of North Greenland. The Late Ordovician virgianids comprise typical taxa of the warm-water Tcherskidium fauna (e.g. Tcherskidium tenuicostatum, Proconchidium schleyi, Holorhynchus giganteus, and Deloprosopus dawesi sp. nov.). Among the early Silurian taxa, Virgiana hursti sp. nov. occurs as abundant shell beds, similar to other congeneric species in Laurentia, but has somewhat larger internal skeletal structures, albeit not as extravagantly developed as in the late Katian virgianids; Boraeloides balderi gen. et sp. nov. shows extreme thickening of shell wall and internal structures, approaching the extravagant calcification of Katian virgianids. The highly distinct mid-Aeronian stricklandioid brachiopod genus, Kulumbella, characterized by a shell with criss-cross (divaricate) ribbing, also occurs in North Greenland, represented by K. heimdalli sp. nov., which has the largest and most strongly biconvex shells for the genus. Palaeogeographically, the Late Ordovician virgianid fauna of Laurentia was highly distinct, confined to the low–mid tropical latitudes north of the palaeoequator. In comparison, the early Silurian (Rhuddanian) Virgiana and some related taxa in Laurentia spanned the tropics of both hemispheres, forming extensive shell beds in carbonate basins, although Borealis and Borealoides gen. nov. remained confined largely to the northern hemisphere, suggesting a certain level of provincialism extending into the earliest Silurian. The unusual abundance and richness of the virgianid faunas in North Greenland is likely explained by a palaeoecological preference for warm-water carbonate settings.

opencc-zeroJan 2024View details →

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Supplementary files for: The oldest complete jawed vertebrates from the early Silurian of China

Molecular studies suggest that the origin of jawed vertebrates was no later than the Late Ordovician period (around 450 million years ago (Ma)). Together with disarticulated micro-remains of putative chondrichthyans from the Ordovician and early Silurian period, these analyses suggest an evolutionary proliferation of jawed vertebrates before, and immediately after, the end-Ordovician mass extinction. However, until now, the earliest complete fossils of jawed fishes for which a detailed reconstruction of their morphology was possible came from late Silurian assemblages (about 425 Ma). The dearth of articulated, whole-body fossils from before the late Silurian has long rendered the earliest history of jawed vertebrates obscure. Here we report a newly discovered Konservat-Lagerstätte, which is marked by the presence of diverse, well-preserved jawed fishes with complete bodies, from the early Silurian (Telychian age, around 436 Ma) of Chongqing, South China. The dominant species, a 'placoderm' or jawed stem gnathostome, which we name Xiushanosteus mirabilis gen. et sp. nov., combines characters from major placoderm subgroups and foreshadows the transformation of the skull roof pattern from the placoderm to the osteichthyan condition. The chondrichthyan Shenacanthus vermiformis gen. et sp. nov. exhibits extensive thoracic armour plates that were previously unknown in this lineage, and include a large median dorsal plate as in placoderms, combined with a conventional chondrichthyan bauplan. Together, these species reveal a previously unseen diversification of jawed vertebrates in the early Silurian, and provide detailed insights into the whole-body morphology of the jawed vertebrates of this period.

opencc-zeroMay 2024View details →

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Fig. 4 in Mat-forming coccoid cyanobacteria from early Silurian marine deposits of Sudetes, Poland

Fig. 4. Size−frequency histogram of cells from the early Silurian mats.