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Fig. 1 in Ordovician enigmatic sclerite-type elements from western Argentina: possible oldest axial components of alcyonacean octocorals

Fig. 1. The geographical and geological context of the Ordovician alcyonacean octocoral Catenatus argentinus gen. et sp. nov. from the San Juan Formation, Argentina. A. Location map of the studied localities with Ordovician alcyonacean sclerite-type elements from the Argentine Precordillera, San Juan Province, Argentina (1, Oculta Creek, Sierra de Los Cauquenes; 2, Los Gatos Creek, Cerro Viejo; 3, Amarilla Creek, Cerro Viejo; 4, Punta Negra Anticline; 5, Sierra de Rinconada). B. Simplified stratigraphic column of the San Juan Formation in the Argentine Precordillera, with location of the productive samples.

Fig. 8 in Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae

Fig. 8. Reconstructions of cranidia (A1–E1) and pygidia (A2–E2) of different members of the subfamily Pilekiinae. A. Anacheirurus adserai (Vela and Corbacho, 2008). B. Parapilekia olesnaensis (Růžička, 1935), based on Mergl (2006). C. Tesselacauda depressa Ross, 1951, based on Adrain and Karim (2019). D. Landyia elizabethae Jell, 1985, based on Jell (1985). E. Macrogrammus rafi Edgecombe, Chatterton, Vaccari, and Waisfeld, 1999, based on Edgecombe et al. (1999).

Fig. 2 in Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae

Fig. 2. Cheirurid trilobites Anacheirurus adserai (Vela and Corbacho, 2007) from the Fezouata Shale, Araneograptus murrayi Zone, Tremadocian, Lower Ordovician, near Beni Zouli, Zagora Province, Morocco (A, B) and Lehua vinculum (Barrande, 1852) from the Dobrotivá Formation, upper Darriwilian to lowermost Sandbian, Zaječov-Svatá Dobrotivá, Czech Republic (C–E). A. YPM 522182, part, complete holaspid with hypostome impressed. B. YPM 530933, complete holaspid. C. NM L19066, complete holaspid. D. NM L19075, complete cranidium. E. JV1607, anterior half of an holaspid specimen. Specimens in C–E covered by ammonium chloride.

Fig. 9 in Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae

Fig. 9. Biramous appendages reconstruction for the cheirurid trilobite Anacheirurus adserai, showing the anterior (A) and the posterior (B) morphology. Dashed lines indicate inferred proximal parts of the appendages.

Fig. 5 in Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae

Fig. 5. Endopodites of the cheirurid trilobite Anacheirurus adserai (Vela and Corbacho, 2007) from the Fezouata Shale, Araneograptus murrayi Zone, Tremadocian, Lower Ordovician, near Beni Zouli, Zagora Province, Morocco. A. Part of YPM 226573, general view (A1), close-up of the endopodites (A2) and explanatory drawing (A4), close-up of the distal claw (A3) and explanatory drawing (A5). B. Counterpart of YPM 226573, general view (B1), close up of the endopodites (B2) and explanatory drawing (B3), close up of the endopodites (B4) and explanatory drawing (B5), close up of the area pointed out in B4 (B6), arrows showing long endites on podomere 2 and 3. Numbers represent podomere number. Abbreviations: ar, axial ring.

Fig. 7 in Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae

Fig. 7. Exopodities of the cheirurid trilobite Anacheirurus adserai (Vela and Corbacho, 2007) (YPM 517074) from the Fezouata Shale, Araneograptus murrayi Zone, Tremadocian, Lower Ordovician, near Beni Zouli, Zagora Province, Morocco. Photographs: general view (A1), close-up of the exopodites (A2) and explanatory drawing (A3), close up to the ninth exopodite (A4) and explanatory drawing (A5). Scale bars 1 mm. Abbreviations: ar, axial ring; ex, exopodite.

Fig. 1 in Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae

Fig. 1. Cheirurid trilobite Anacheirurus adserai (Vela and Corbacho, 2007) from the Fezouata Shale, Araneograptus murrayi Zone, Tremadocian, Lower Ordovician, near Beni Zouli, Zagora Province, Morocco. A. MGL 102179, complete specimen (A1) and anterior region of the counterpart (A2); arrow pointing the antennae. B. MGL 102170, close-up of the posterior region of the trunk; arrow pointing the disarticulated pygidium. C. ML20-269198, latex cast of the counterpart. D. YPM 525125, close up of the posterior region of the trunk; arrow pointing the articulation between the thorax and the pygidium. Specimens in A1 and C coated with ammonium chloride. Scale bars 1 mm.

Fig. 6 in Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae

Fig. 6. Cheirurid trilobite Anacheirurus adserai (Vela and Corbacho, 2007) (MGL 102172) from the Fezouata Shale, Araneograptus murrayi Zone, Tremadocian, Lower Ordovician, near Beni Zouli, Zagora Province, Morocco. Photographs under alcohol: general view (A1), close-up of the exopodites A2) and explanatory drawing (A3). Scale bars 1 mm. Abbreviations: ar, axial ring.

Fig. 11 in Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae

Fig. 11. Ordovician diversity of Cheiruridae species across individual time slices, as defined in Adrain (2013). The dashed line represents the boundary between Tremadocian and Floian; blue, members of the subfamily Pilekiinae; red, members of the rest of Cheiruridae subfamilies excluding pilekiids. Data based on Adrain (2013, personal communication 2020).

Fig. 10 in Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae

Fig. 10. Trilobite exopodite reconstructions grouped by geological age. A. Eoredlichia intermediata (Lu, 1940), based on Ramsköld and Edgecombe 1996). B. Hongshiyanaspis yiliangensis Zhang and Lin in Zhang et al., 1980, based on Zeng et al. (2017). C. Redlichia rex Holmes, 2019, based on Holmes et al. (2019). D. Olenoides serratus (Rominger, 1887), based on Whittington 1980). E. Anacheirurus adserai (Vela and Corbacho, 2007). F. Ceraurus pleurexanthemus Green, 1832, based on Størmer (1951). G. Triarthrus eatoni (Hall, 1838), based on Whittington and Almond (1987). H. Cryptolithus bellulus (Ulrich, 1879), based on Campbell (1975). I. Chotecops ferdinandi Kayser, 1880), based on Bruton and Haas (1999).

Fig. 3 in Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae

Fig. 3. Juveniles of the cheirurid trilobite Anacheirurus adserai from the Fezouata Shale, Araneograptus murrayi Zone, Tremadocian, Lower Ordovician, near Beni Zouli, Zagora Province, Morocco. A. MGL 104146, late meraspid stage. B. MGL 102153, early holaspid stage. C. MGL 104533, early holaspid stage. Specimens in B, C covered by ammonium chloride. Scale bars 1 mm.

Fig. 4 in Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae

Fig. 4. Endopodites of the cheirurid trilobite Anacheirurus adserai (Vela and Corbacho, 2007) from the Fezouata Shale, Araneograptus murrayi Zone, Tremadocian, Lower Ordovician, near Beni Zouli, Zagora Province, Morocco. A. MGL 103863, photograph under alcohol with polarized light (A1), explanatory drawing with podomere numbers (A2). B. MGL 102225, photograph under alcohol with polarized light (B1), explanatory drawing with endopodite numbers (B2). Scale bars 1 mm. Abbreviations: ar, axial ring.

Fig. 13 in Variability of conch morphology in a cephalopod species from the Cambrian to Ordovician transition strata of Siberia

Fig. 13. Restoration of the conch of Ruthenoceras elongatum Korde, 1949 from the Ust-kut Formation of Siberia, with hypothetical subspherical apex based mostly on ZPAL N. IV/4 (Fig. 5A). A. Septum in proximal view. B. Conch in lateral view with the body and proximal part of sipho exposed. C. The body and a portion of sipho in dorsal view.

Fig. 10 in Variability of conch morphology in a cephalopod species from the Cambrian to Ordovician transition strata of Siberia

Fig. 10. Contours of all the ellesmeroceratid nautiloid conchs (interpreted below as Ruthenoceras elongatum Korde, 1949) from sample Ang-4, block No. 1, probably latest Furongian Ust-kut Formation found at Pashino on the Angara River, Siberia, Russia, superimposed on the most complete specimen ZPAL N. IV/4 (Fig. 5A).

Fig. 9 in Variability of conch morphology in a cephalopod species from the Cambrian to Ordovician transition strata of Siberia

Fig. 9. Apical parts of ellesmeroceratid nautiloid conchs (interpreted below as Ruthenoceras elongatum Korde, 1949) from sample Ang-4, block No. 1, probably latest Furongian Ust-kut Formation found at Pashino on the Angara River, Siberia, Russia. A, B. ZPAL N. IV/11 and 117, respectively; conchs with low expansion rate rate in lateral (A1, B1) and dorsal (A2, B2) views. C–E. ZPAL N. IV/103, 18, and 114, respectively; conchs with high expansion rate rate in lateral (C1, D, E2), ventral (C2), and dorsal (E1) views.

Fig. 6 in Variability of conch morphology in a cephalopod species from the Cambrian to Ordovician transition strata of Siberia

Fig. 6. Suture lines of ellesmeroceratid nautiloids from sample Ang-4, block No. 1, probably latest Furongian Ust-kut Formation found at Pashino on the Angara River, Siberia, Russia. A–H. ZPAL N. IV/109, 111, 10, 27, 56, 51, 48, and 9, respectively. Scale bars 2 mm.

Fig. 1 in Variability of conch morphology in a cephalopod species from the Cambrian to Ordovician transition strata of Siberia

Fig. 1. Loose block No. 1 of a stromatolitic limestone with abundant nautiloid conchs of the Ust-kut Formation (latest Furongian or earliest Tremadocian) found on the left bank of the Angara River at the former village Pashino. A. The block partially exploited for fossils. B. Stromatolite columns with empty cavities and a laminar cover above. C. A piece of the rock with exposed nautiloids. D. Polished rock surface (note similarity of the specimen in the middle to the holotype of Ruthenoceras elongatum Korde, 1949). E. Naturally abraded upper surface of the stromatolite columns.

Fig. 12 in Variability of conch morphology in a cephalopod species from the Cambrian to Ordovician transition strata of Siberia

Fig. 12. Relationships between the basic conch geometry aspects of ellesmeroceratid nautiloids from sample Ang-4, block No. 1, probably latest Furongian Ust-kut Formation found at Pashino on the Angara River, Siberia, Russia. A. With an increase of septum depth its obliquity increases even stronger but the correlation is rather loose. B. If non-linear correspondence to ontogeny of these phragmocone aspects is ignored, the pattern of variability appears roughly unimodal. C–E. Also the distribution of indices of the living chamber elongation, septum inclination and depth does not reveal any multimodality. The regression lines in A and B are intuitive (drawn by hand and not computed) because only one dimension (aperture height) is measurable in smallest conchs.

Fig. 11 in Variability of conch morphology in a cephalopod species from the Cambrian to Ordovician transition strata of Siberia

Fig. 11. Ontogenetic change of conch geometry aspects of ellesmeroceratid nautiloids from sample Ang-4, block No. 1, probably latest Furongian Ust-kut Formation found at Pashino on the Angara River, Siberia, Russia. Aperture height is used as a measure of an individual age. A–C. Characters with linear growth pattern. D–G. Characters with non-linear growth pattern. The regression lines are intuitive (drawn by hand and not computed) because only one dimension (aperture height) is measurable in smallest conchs.

Fig. 7 in Variability of conch morphology in a cephalopod species from the Cambrian to Ordovician transition strata of Siberia

Fig. 7. Medial sections of ellesmeroceratid nautiloids interpreted below as Ruthenoceras elongatum Korde, 1949, from sample Ang-4, block No. 1, probably latest Furongian Ust-kut Formation found at Pashino on the Angara River, Siberia, Russia. A, B. Mature phragmocones with moderately oblique septa, ZPAL N. IV/14 and 15, respectively. C. Almost complete juvenile phragmocone ZPAL N. IV/92 showing extend of diaphragms in the siphuncle. D–G. Apical parts of phragmocones (not strictly medial sections), ZPAL N. IV/115, 118, 121, and 125, respectively. H. Mature phragmocone ZPAL N. IV/16 with extremely oblique septa. I. Straight part of the phragmocone ZPAL N. IV/17 with oblique diaphragms. Wet ground surfaces (A1, B, C1, D–G, H1, I) and acetate peels (A2, C2, H2).