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FIGURE 5 in A trilobite cluster from the Silurian Rochester Shale of New York: predation patterns and possible defensive behavior

FIGURE 5. Specimens of Arctinurus boltoni with injuries to the thorax (A, B) and with reconstruction that mimics an injury (C, D), under plain and UV light. Arrows point to injuries described in the text. Scale bar = 1 mm. A–B, AMNH-FI-101518. C–D, AMNH-FI-101516.

FIGURE 4 in A trilobite cluster from the Silurian Rochester Shale of New York: predation patterns and possible defensive behavior

FIGURE 4. Further specimens of Arctinurus boltoni with injuries to the pygidium, under plain and UV light. Arrows point to injuries described in the text. Scale bar = 1 mm. A–B, AMNH-FI-101529. C–D, AMNH- FI-101530. E–F, AMNH-FI-101531.

FIGURE 3 in A trilobite cluster from the Silurian Rochester Shale of New York: predation patterns and possible defensive behavior

FIGURE 3. Specimens of Arctinurus boltoni with injuries to the pygidium, under plain and UV light (with brighter areas indicating parts of reconstructed exoskeleton). Arrows point to injuries described in the text. Scale bar = 1 mm. A–B, AMNH-FI-101521. C–D, AMNH-FI-101527.

FIGURE 2 in A trilobite cluster from the Silurian Rochester Shale of New York: predation patterns and possible defensive behavior

FIGURE 2. Diagram of 12 landmarks selected to describe the overall shape of the exoskeleton of Arctinurus boltoni.

FIGURE 7 in A trilobite cluster from the Silurian Rochester Shale of New York: predation patterns and possible defensive behavior

FIGURE 7. Principal components analysis of landmark data, with 49.5% variance in the data explained by the first two PCs (PC1=29.7%, PC2=19.8%). PC1 describes the variation in the intersection of the occipital furrow and anterior-posterior axis and junction points between posterior margin of the 11th tergite. PC2 mostly describes variation in cephalic width.

FIGURE 6 in A trilobite cluster from the Silurian Rochester Shale of New York: predation patterns and possible defensive behavior

FIGURE 6. Arctinurus boltoni specimen AMNH-FI-101520 with injuries to the thorax and pygidium, under A, plain and B, UV light. Arrows point to injuries described in the text. Scale bar = 1 mm.

opencc-by-4.0Jul 2005View details →

Figure 2 in The histology and affinities of sinacanthid fishes: primitive gnathostomes from the Silurian of China

Figure 2. Histology of sinacanthid spines. A, montage of a single transverse section; B, detail showing clear boundary (arrowed) between the outer layer of atubular dentine and lamellar dentine and the inner layer of globular calcified cartilage, note also the pulp cavities beneath each ridge; C, scanning electron micrograph of HCl etched section through ridge and globular calcified cartilage showing boundary (arrowed) between the outer layer and the inner layer; D, detail of globular atubular dentine; E, cross section through presumed juvenile spine ridge showing open pulp cavity; F, globular calcified cartilage lining vascular canal. All transmitted light micrographs using Nomarski interference optics unless otherwise stated. A–D, F, Sinacanthus wuchangensis P'an (1959) from the Tataaiertage Formation, Lower Silurian, Kalpin, Xinjiang, IVPP.V14325; E, Sinacanthus sp. from the Xiushan Formation, Lower Silurian, Shiqian, Guizhou Province, NIGP 139378. Abbreviations: ad, atubular dentine; pc, pulp cavity; ld, lamellar dentine; gcc, globular calcified cartilage; vc, vascular canal. Scale bars: A = 500 Mm; B, C, E = 100 Mm; D, F = 50 Mm.

opencc-by-4.0Dec 2004View details →

Fig. 9 in Strophomenide and orthotetide Silurian brachiopods from the Baltic region, with particular reference to Lithuanian boreholes

Fig. 9. Diagram showing the relative dispositions of E. (Eoplectodonta) and E. (Ygerodiscus) from west to east in the East Baltic platform.

opencc-by-4.0Dec 2004View details →

Fig. 7 in Strophomenide and orthotetide Silurian brachiopods from the Baltic region, with particular reference to Lithuanian boreholes

Fig. 7. Eoplectodonta (E.) penkillensis (Reed, 1917), B20497, Riga Formation (Sheinwoodian, M. riccartonensis Zone), eroded bedding plane with the Clorinda sp., Vilkaviškis−129, 837.1 m, × 3.4.

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

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publicSep 2019View details →

opencc-zeroFeb 2020View details →

Moving towards a better understanding of iterative evolution: an example from the late Silurian Monograptidae (Graptolithina) of the Baltic Basin

Iterative evolution has proved a difficult evolutionary phenomenon to study and interpret. Inferences of causality vary from study to study and quantitatively based phylogenetic reconstruction has never been attempted. In an effort to better understand iterative evolution we employed stratocladistics, gap analysis, and disparity analysis to study the case of the Monograptidae in the aftermath of the late Silurian C. lundgreni extinction event. Our combination of gap analytical and stratocladistic techniques allowed us to elucidate the evolutionary relationships between the studied taxa. Based on our stratocladistic results we recommend the generic reassignment of 5 monograptid taxa. The stratocladistic results, in conjunction with morphological disparity analysis suggest the presence of a persistent developmental potential for the emergence of iteratively evolving characters. This persistent potential appears to be limited by extrinsic ecological constraints, which would have relaxed in the aftermath of the C. lundgreni extinction event. Our findings indicate that iterative evolution in the late Silurian Monograptidae is a product of the interaction of both intrinsic and extrinsic constraints on the acquisition of the iteratively evolving character, with the exact causality being dependent on the particular character.

opencc-by-4.0Dec 2003View details →

Fig. 23. Reticulograptus thomasi n in Dendroid and Tuboid Graptolites from the Llandovery (Silurian) of the Four Mile Creek Area, New South Wales

Fig. 23. Reticulograptus thomasi n.sp., AM F114756, holotype, BF28. Scale bar 1 mm.

opencc-by-4.0Dec 2003View details →

Fig. 2 in Dendroid and Tuboid Graptolites from the Llandovery (Silurian) of the Four Mile Creek Area, New South Wales

Fig. 2. Dendroid graptolite localities on the Bridge Creek sections.

opencc-by-4.0Dec 2003View details →

Fig. 1 in Dendroid and Tuboid Graptolites from the Llandovery (Silurian) of the Four Mile Creek Area, New South Wales

Fig. 1. Location map of the Bridge Creek area of southeastern Australia.

opencc-zeroJan 2024View details →

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-zeroFeb 2024View details →

Measurements of Silurian brachiopod specimens from the Pentland Hills, Scotland

The abundant and diverse brachiopod fauna from the Silurian (upper Llandovery-lower Wenlock) rocks of the Pentland Hills is described within its geographical stratigraphical context. The majority of species are described in detail, discussed and illustrated. A total of 53 species attributable to the following superfamilies are present (numbers of species, including those in open nomenclature, in parentheses): Linguloidea (7), Craniopsoidea (1), Discinoidea (4), Strophomenoidea (9), Plectambonitoidea (2), Chonetoidea (1), Childiopsoidea (2), Skenidioidea (1), Dalmanelloidea (3), Pentameroidea (2), Rhynchonelloidea (4), Atrypoidea (4), Athyridoidea (5), Cyrtioidea (5) and Delthyridoidea (3). Five new species, Leptaena eska, Isorthis (Ovalella) clarksoni, Dicoelosia paratenua, Oglupes scotia and Lissatrypa scotica, are erected. Nevertheless in terms of abundance the fauna is dominated by individuals belonging to the Strophomenoidea, Plectambonitoidea and Dalmanelloidea. The composition of the fauna, its deeper-water setting associated with finer-grained siliciclastic substrates characterizes this Pentlandian biota.

opencc-zeroMay 2024View details →

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-by-4.0May 2024View details →

Data affiliated with "Solid bitumen as an indicator of petroleum migration, thermal maturity, and contact metamorphism: A case study in the Barrandian Basin (Silurian - Devonian), Czech Republic"

Fourier transform infrared (FTIR) spectra affiliated with the publication "Solid bitumen as an indicator of petroleum migration, thermal maturity, and contact metamorphism: A case study in the Barrandian Basin (Silurian - Devonian), Czech Republic" in International Journal of Coal Geology (<a title="Persistent link using digital object identifier" href="https://doi.org/10.1016/j.coal.2024.104493" target="_blank" rel="noreferrer noopener">https://doi.org/10.1016/j.coal.2024.104493</a>). The FTIR data are saved as CSVs under the numbers and names corresponding to Table in Supplement 1. Columns A corresponds to wavenumbers in cm-1, columns B and C to absorbance measured in two measurements.

opencc-zeroJun 2024View details →

Data from: Locomotory and morphological evolution of the earliest Silurian graptolite (Demirastrites) selected by hydrodynamics

Interpretation of the locomotion for biostratigraphic important graptolite taxa is rare and rendered problematic due to their lack of close modern analogues and soft tissues. In this study, based on well-preserved specimens of the early Silurian low-helical spiral Demirastrites Eisel, we reconstructed three-dimensional (3D) Demirastrites models and simulated their locomotion by using computational fluid dynamics. Hydrodynamic properties (outer-wall pressure fields and velocity fields) were obtained and used to test the prevailing hypothesis that the Silurian low helical spiral graptolite Demirastrites could rotate in seawater. The Demirastrites models kept rotating at different velocities in the simulation field, which helped to counteract the impact of the water current and achieve stability. During rotation, higher velocity fields could be observed near the thecal apertures, which meant better access to more nutrient particles in the sea water. Our simulation thus confirmed the rotating locomotory pattern of the Silurian low conical graptolite Demirastrites for the purpose of better feeding efficiency and turbarium stability. Moreover, we analysed how the evolution of structural innovations, such as the density and width of thecae and the curvature angle of the rhabdosome within the recovered geological lineages of Demirastrites, were influenced and selected by hydrodynamics. The results showed that Demirastrites lineages evolved towards increased stability and higher rotation velocity. Our study highlights the importance of hydrodynamic constraints serving as hidden abiotic factors shaping the evolution of planktonic graptolites.