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Fig. 3 in The tarphyceratid cephalopod Trocholites in the Middle-Upper Ordovician of the Prague Basin -the Baltican element in peri-Gondwana

Fig. 3. Parameters used to measure and describe the specimens studied herein (after Korn 2010). Abbreviations: ah, apertural height; cl, cameral length; dm, shell diameter across centre of umbilicus; fh, foramen height; iz, imprint zone; uw, umbilical width; wh, whorl height; ww, whorl width. Line drawings are based on NM L 63626 (holotype of Trocholites chaloupkai sp. nov.).

Fig. 3 in Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America

Fig. 3. Polished sections of samples from the lower Tremadocian (Ordovician) of Quebrada de Arenal, Trancas section, Cordillera Oriental, Jujuy, Argentina, showing the random orientation of the conchs of Ellesmeroceras humahuacaensis sp. nov. A. CEGH-UNC 27489, showing diagonal and transverse views of specimens. B. CEGH-UNC 27491. B1, several cephalopods tangentially cut, and fragments of shell material. B2, some almost transverse and oblique sections of cephalopods and a variety of undetermined shell material. B3, transverse and sagittal cuts of cephalopods and a variety of randomly oriented shell material. Scale bars 5 mm.

Fig. 2. A in Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America

Fig. 2. A. Map of South America showing the main Paleozoic geological provinces of NW Argentina. B. Map of the study area (Jujuy Province, Argentina). The satellite image from Google Earth. QA, Quebrada de Arenal (-23.474677, -65.337646); QY, Quebrada de Yacoraite (-23.3321972, -65.457527). C. General view of the outcrop where the specimens were collected along the Quebrada de Arenal. This interval is characterized by sandstone interbedded with a general interval of siltstone. D. Regional biostratigraphy and lithostratigraphy correlated with the map intervals used. Modified and updated from Balseiro and Waisfeld (2013) and Vaucher et al. (2020). R. f. anglica, Rhabdinopora flabelliformis anglica. E. Stratigraphic section of the Quebrada de Arenal with the main facies assemblages (FA) that defined the section. Modified from Vaucher et al. (2020). The position where the samples were collected is indicated and belongs to Kainella merdionalis Trilobite Biozon. Til., Tilcara Member; R., Ruspaca Member; K. t., Kainella teiichii.

Fig. 1 in Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America

Fig. 1. Cambrian and early Tremadocian cephalopod records from different localities within the paleotropical belt (compiled from literature).Abbreviations: Fm., formation; Mb., Member.

Fig. 2 in The tarphyceratid cephalopod Trocholites in the Middle-Upper Ordovician of the Prague Basin -the Baltican element in peri-Gondwana

Fig. 2. Correlation of the Dobrotivá and Zahořany formations (greyed-out levels) with global and Ibero-Bohemian chronostratigraphic units, and the herein discussed occurrence of Trocholites. Modified from Kraft et al. (2015), Fatka and Budil (2022), and Kraft et al. (2023).

Fig. 1 in The tarphyceratid cephalopod Trocholites in the Middle-Upper Ordovician of the Prague Basin -the Baltican element in peri-Gondwana

Fig. 1. Map of Ordovician rocks of the Prague Basin and position of the localities, from which the two studied specimens originate: Locality 1, Březová Hůrka near Starý Plzenec; Locality 2, Praha-Štěrboholy. Modified from Manda (2008).

Fig. 6 in Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America

Fig. 6. Ellesmeroceratid cephalopod Ellesmeroceras humahuacaensis sp. nov. (paratype CEGH-UNC 27495a) from the lower Tremadocian (Ordovician) of Quebrada de Arenal, Trancas section, Cordillera Oriental, Jujuy, Argentina. A1, external lateral (slightly oblique) view of the coated specimen; A2, longitudinal micro-CT section; A3, detail of the apical part and adjacent chambers viewed in the micro-CT scan.

Fig. 7 in The tarphyceratid cephalopod Trocholites in the Middle-Upper Ordovician of the Prague Basin -the Baltican element in peri-Gondwana

Fig. 7. Tarphyceratid cephalopod Trocholites chaloupkai sp. nov. from Praha-Štěrboholy, central Bohemia, Czech Republic, upper part of the Zahořany Formation (lower Katian, Upper Ordovician). A. Holotype NM L 63626, general view on shell ornament (A1); SEM image of shell ornament (A2) on umbilical wall of the outer whorl, coalescent ornament elements form a net-like (fenestrate) pattern; SEM image with detail of shell ornament (A3), transverse elements have a lamellar character and are imbricated adaperturally, the elements form undulating ridges that are locally coalescent with each other.

Fig. 5 in Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America

Fig. 5. Ellesmeroceratid cephalopod Ellesmeroceras humahuacaensis sp. nov. from the lower Tremadocian (Ordovician) of Quebrada de Arenal, Trancas section, Cordillera Oriental, Jujuy, Argentina. A. CEGH-UNC 27494a in lateral view (coated with ammonium chloride A1, without coating A2), intermediate view between lateral and dorsal (A3). Note the sutural lateral lobes and the bent apical part of the conch. B. CEGH-UNC 27494c in dorsal view. Note the specimen is crossed by a fracture in the rock that was fixed. C. CEGH-UNC 27501 in dorsal view with the apical part rather deformed. D. CEGHUNC 27496a in dorsal view. E. CEGH-UNC 27496c in dorsal view, partially broken externally. F. CEGH-UNC 27491b in dorsal view, with shell wall. G. CEGH-UNC 27491c in external view, showing the growth lines. Scale bars 2 mm.

Fig. 4 in Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America

Fig. 4. Virtual reconstruction of the ellesmeroceratid cephalopod Ellesmeroceras humahuacaensis sp. nov. from the lower Tremadocian, Lower Ordovician of Quebrada de Arenal, Trancas section, Cordillera Oriental, Jujuy, Argentina based on composite data of the CT scan analysis of sample CEGH-UNC 27495 (three specimens), in dorsal (A1) and lateral (A2) views.

Fig. 5 in The tarphyceratid cephalopod Trocholites in the Middle-Upper Ordovician of the Prague Basin -the Baltican element in peri-Gondwana

Fig. 5. Tarphyceratid cephalopod Trocholites chaloupkai sp. nov. from Praha-Štěrboholy, central Bohemia, Czech Republic, upper part of the Zahořany Formation (lower Katian, Upper Ordovician). Holotype NM L 63626, optical microscope photograph of whitened specimen in lateral view (A1); micro-CT images showing frontal (A2) and ventral (A3) views, note ventral lobe of suture line; virtual longitudinal sections in sagittal plane showing partly preserved septa in last (A4) and penultimate (A7) whorls; virtual longitudinal section in median plane (A8) showing the siphuncle and the earliest whorl of the phragmocone; virtual transverse sections in slightly eccentric (A5) and central (A6) planes documenting whorl profile shape and siphuncle.

Fig. 7 in Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America

Fig. 7. Polished sections with different orientations of the ellesmeroceratid cephalopod Ellesmeroceras humahuacaensis sp. nov. from the lower Tremadocian (Ordovician) of Quebrada de Arenal, Trancas section, Cordillera Oriental, Jujuy, Argentina. A. CEGH-UNC 27489a, sagittal and somewhat oblique cut showing part of the siphuncle, the living chamber and the camerae. B. CEGH-UNC 27489b, sagittal and oblique cut of part of phragmocone showing septal necks. C. CEGH-UNC 27489c, sagittal and oblique cut of part of phragmocone broken apically showing cameral depth. D. CEGH-UNC 27489d, oblique cut of a fragment of conch with some broken septa and part of the siphuncle visible apically. E. CEGH-UNC 27489e, oblique cut of part of a conch in which the siphuncle is partially visible. F. CEGH-UNC 24784a, nearly longitudinal cut showing the siphuncle with septal necks and connecting rings. G. CEGH-UNC 24784b, detail of siphuncle in an oblique section. Scale bars 2 mm.

Fig. 8 in Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America

Fig. 8. Early Tremadocian (Ordovician) cephalopods from Quebrada de Arenal, Trancas section, Cordillera Oriental, Jujuy, Argentina. A. Ellesmeroceratid Ellesmeroceras sp. (CEGH-UNC 27496b) in oblique-lateral (A1) and oblique-ventral (A2) view of the uncoated specimen, and oblique-lateral view of the coated specimen (A3). Arrow points to the siphuncle. Note the sinuosity of the suture lines. B. Bassleroceratid Bassleroceras? sp. (CEGH-UNC 27497) in lateral view (B1, B2) showing exogastric curvature, low expansion rate, and external siphuncle, in apical view of the apicalmost septum preserved (B3, B4), showing the slightly compressed shape and the siphuncle position. Photographs (B1, B3) and schematic drawings (B2, B4) Scale bars: A, 5 mm, B1, B2, 2 mm; B3, B4, 1 mm. discarded order Bassleroceratida (Evans 2011: 22, and dis- 3.2 mm correspond to part of the living chamber and 4.1 cussion and references therein). We followed here the pro- mm to part of the phragmocone. It has an oral dorsoventral posal by Pohle et al. (2022), in which the family is located diameter of ca. 3 mm, an apical dorsoventral diameter of c within the subclass but not included in any particular or- 2.6 mm, and an apical lateral diameter of ca. 2.1 mm. The der, although Kröger and Pohle (2021) included the family cross-section is slightly compressed (0.8), and the siphuncle within Ellesmerocerida. See Evans (2011) for further discus- is rather large, ventral and marginal (Fig. 8B), with a diamesion about the family Bassleroceratidae. ter 34 % of that the conch diameter. The chambers are very short, ca. 0.3 mm long (Fig. 8B1). There are 10 chambers in Genus Bassleroceras Ulrich and Foerste, 1935 a length equivalent to the conch diameter, i.e., an RCL of 0.1. Type species: Orthoceras perseus Billings, 1865, from the St. Armand At 2.3°, the expansion rate is very low. CEGH-UNC 27480a Limestone, near Phillipsburg, Missisquoi County, Quebec, Canada. is a 7.4 mm long fragment of a slightly exogastric conch, of Tremadocian, Lower Ordovician. which 4 mm corresponds to part of the living chamber and Bassleroceras? sp. 3.4 mm to the phragmocone. Adapically, the dorsoventral diameter is ca. 3 mm, and the siphuncle is 1 mm wide, or Fig. 8B. 33% of that the conch diameter. The chambers are 0.3 mm Material.—CEGH-UNC 27497 and 27480a, from the Alfa- long, indicating an RCL of 0.08. The SCI is 0.16. rcito Member, Santa Rosita Formation, lower Tremadocian, Remarks.—The slightly exogastric curvature of these spec- Lower Ordovician, Quebrada de Arenal, Trancas section, imens, along with the very low expansion rate of the conch, Jujuy, Argentina. suggests that they can be assigned to the Basslerocertidae. Description.—CEGH-UNC 27497 is a 7.3 mm long frag- We would need more material in order to investigate interment of a slightly exogastrically curved conch, of which nal structures and determine more precisely the taxonomic

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.