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FIGURE 5 in Computational fluid dynamics modeling of fossil ammonoid shells

FIGURE 5. Coefficient of drag results from Scheme 1 (green) and Scheme 3 (blue) plotted against Re compared against the data from Jacobs (1992; black). Comparisons shown are for Sphenodiscus (left) and Oppelia (right).

FIGURE 3 in Computational fluid dynamics modeling of fossil ammonoid shells

FIGURE 3. An illustration of the computational domain of the simulation. The model target (an ammonoid in this case) is shown as a circle. Each arrow indicates a distance from the shell to a target face of the computational domain. These arrows represent the straight-line distance between the nearest edge of the shell (not the shell's midpoint) and the corresponding wall as per the methods of Shiino, Kuwazuru, and Yoshikawa (2009). Dimensions in the figured example correspond to those of Scheme 3 (see Table 1)

FIGURE 4 in Computational fluid dynamics modeling of fossil ammonoid shells

FIGURE 4. Hemisphere simulation data plotted as velocity versus % difference from the literature baseline (Blevins 1984). Velocities shown are within a range in which the drag coefficient of a hemisphere is relatively stable around a value of 1.17 (Blevins, 1984). The drag values used to derive this plot are given in Appendix 3.

FIGURE 1 in Computational fluid dynamics modeling of fossil ammonoid shells

FIGURE 1. An outline of the workflow from model creation to completed simulation. Boxes are colored based on the general process they are included in: Case generation (blue), Mesh generation (purple), and numerical set-up (green). Two tracks are shown for case generation: one in which a model is created in blender from measurement data (below the dotted line) and the other where the model is created using a Structure from Motion technique such as laser scanning or photogrammetry (above the dotted line). Software used in each process is noted in "()" outside its respective step.

FIGURE 11 in Computational fluid dynamics modeling of fossil ammonoid shells

FIGURE 11. Plots of pressure overlain with water velocity vectors for the Serpenticone and Oxycone shells at both 15 cm/s (A) and 5 cm/s (B) inlet velocities. At 15 cm/s the flow around the Serpenticone shell is more chaotic and there is a buildup of pressure at around the trailing coils compared to the Oxycone shell. This difference mostly disappears at 5 cm/s.

FIGURE 9 in Computational fluid dynamics modeling of fossil ammonoid shells

FIGURE 9. Water velocity around the Sphenodiscus shell at inlet velocities of 15 cm/s (A) and 5 cm/s (B). Areas of slow water velocity caused by viscous interactions are larger to the sides and immediately behind the shell at the lower velocity because water is less readily shed.

Fig. 12 in The ammonoid recovery after the end-Permian mass extinction: Evidence from the Iran-Transcaucasia area, Siberia, Primorye, and Kazakhstan

Fig. 12. Representatives of Wuchiapingian ammonoids from the Hambast Formation of Abadeh, Central Iran. A. Pseudogastrioceras abichianum (Möller, 1879), DVGI, no. 10/850 (most likely Clarkina leveni Zone). B. Paraceltitites sp., DVGI, no. 1/850 (most likely Clarkina transcaucasica Zone): right lateral (B1) and ventral (B2) views. C. Paratirolites waageni (Stoyanov, 1910), DVGI no. 11/850 (Hambast Formation, upper Member 7), late Dorashamian Paratirolites kittli Zone.

Fig. 10 in The ammonoid recovery after the end-Permian mass extinction: Evidence from the Iran-Transcaucasia area, Siberia, Primorye, and Kazakhstan

Fig. 10. Ammonoids suture lines from lower Olenekian, Mesohedenstroemia bosphorensis Zone; SMID quarry at the Artyom environs, south Primorye. A. Ceratitid Inyoites sedini sp. nov., DVGI 1/851 (holotype). Suture line, height 21.2 mm (A1); whorl cross−section, height 21.1 mm (A2). B. Suture line of phylloceratid Subbalhaeceras shigetai gen. and sp. nov., DVGI 2/851 (holotype). Abbreviations: L, lateral lobe; U, umbilical lobe; V, ventral lobe.

Fig. 7 in The ammonoid recovery after the end-Permian mass extinction: Evidence from the Iran-Transcaucasia area, Siberia, Primorye, and Kazakhstan

Fig. 7. Mangyshlak, Kazakhstan: temporal ranges of ammonoid genera of the upper Olenekian. Abbreviation: Reg. Series, Regional Series.

Fig. 1 in The ammonoid recovery after the end-Permian mass extinction: Evidence from the Iran-Transcaucasia area, Siberia, Primorye, and Kazakhstan

Fig. 1. Study areas: 1, Iran−Transcaucasia area; 2, Siberia and northern Russian Far East; 3, southern Russian Far East (South Primorye and Amur River); 4, Mangyshlak, Kazakhstan.

Fig. 2 in The ammonoid recovery after the end-Permian mass extinction: Evidence from the Iran-Transcaucasia area, Siberia, Primorye, and Kazakhstan

Fig. 2. View of the Permian–Triassic sequences of the section from the Wuchiapingian–Changhsingian Hambast (H) Formation to latest Changhsigian– Induan Elikah (E) Formation at the Hambast region, 28 km to south−western of the village of Abaraku, Abadeh, Central Iran.

Fig. 8 in The ammonoid recovery after the end-Permian mass extinction: Evidence from the Iran-Transcaucasia area, Siberia, Primorye, and Kazakhstan

Fig. 8. Suture lines of some Prolecanitida. A. Mesohedenstroemia olgae sp. nov., DVGI 2/851 (holotype), height 18.4 mm; Lower Olenekian, Mesohedenstroemia bosphorensis Zone; SMID quarry at the Artyom environs, south Primorye. B, C. Hedenstroemia tscherskii (Popov, 1961). Lower Olenekian, Lepiskites kolymensis Zone; Kenyelichi River, Kolyma River basin. B. DVGI 256−3b, height 60.0 mm (B1) and 73.0 mm (B2). C. DVGI 255−19c, height 73.0 mm. Abbreviations: D, dorsal lobe; I, inner lateral lobe; L, lateral lobe; U, umbilical lobe; V, ventral lobe.

Fig. 11 in The ammonoid recovery after the end-Permian mass extinction: Evidence from the Iran-Transcaucasia area, Siberia, Primorye, and Kazakhstan

Fig. 11. Suggested phylogenetic relationships in the Changhsingian–Olenekian goniatitid, prolecanitid, ceratitid, and phylloceratid ammonoid superfamilies and families.

Fig. 9 in The ammonoid recovery after the end-Permian mass extinction: Evidence from the Iran-Transcaucasia area, Siberia, Primorye, and Kazakhstan

Fig. 9. Some Early Olenekian Prolecanitida, Ceratitida, and Phylloceratida from Lower Olenekian, Mesohedenstroemia bosphorensis Zone; SMID quarry at the Artyom environs, South Primorye. A. Prolecantid Mesohedenstroemia olgae sp. nov., DVGI 2/851 (holotype), right lateral (A1) and ventral (A2) views. B. Ceratitid Inyoites sedini sp. nov., DVGI 1/851 (holotype). C. Phylloceratid Subbalhaeceras shigetai gen. and sp. nov., DVGI 2/851 (holotype), right lateral (C1), left lateral (C2), ventral (C3) views.

Fig. 9 in Form and formation of flares and parabolae based on new observations of the internal shell structure in lytoceratid and perisphinctid ammonoids

Fig. 9. Transition of parabolae and flares in Analytoceras hermanni (Gümbel, 1868) (BSPG Man-x) from Bihati river valley south of Baun, SW Timor, Hettangian, Jurassic (compare Hoffmann and Keupp 2010); in ventral (A) and lateral (B) views.

Fig. 8 in Form and formation of flares and parabolae based on new observations of the internal shell structure in lytoceratid and perisphinctid ammonoids

Fig. 8. Internal structure of parabolae (transversal section) in Choffatia sp. (BSPG MAn-4519) from Dubki near Saratov, SW Russia; Upper Callovian, Jurassic. A. Parabola with notches. B–E. Discontinuity of the parabolae, the primary shell forms slots at the position of the notches. A secondary shell is attached from beneath. The relief is compensated by the dorsal inner prismatic layer. Abbreviations: apc, apertural prismatic coating; dipl, dorsal inner prismatic layer; ipl, inner prismatic layer; ncl 1/2, nacreous layer of the primary/secondary shell.

Fig. 7 in Form and formation of flares and parabolae based on new observations of the internal shell structure in lytoceratid and perisphinctid ammonoids

Fig. 7. Internal structure of parabolae (median section, growth direction right) in Choffatia sp. (BSPG MAn-4520) from Dubki near Saratov, SW Russia; Upper Callovian, Jurassic. A, B. Discontinuity of the parabola, the primary nacreous layer ends abruptly. A secondary nacreous layer is attached from beneath. The relief is compensated by the dorsal inner prismatic layer. C. Discontinuity of parabolae at the position of the notches. The primary shell bends outwards and has an apertural prismatic coating. The secondary shell is attached from beneath. In front of the free edge of the primary shell a symmetric, prismatic thickening is formed. The dorsal shell compensates the relief. D. Lateral parts of the notches show the typical outward undulation of the new shell of the parabolic node. Abbreviations: apc, apertural prismatic coating; dipl, dorsal inner prismatic layer; dncl, dorsal nacreous layer; dopl, dorsal outer prismatic layer; ncl 1/2, nacreous layer of the primary/secondary shell; opl 1/2, outer prismatic layer of the primary/secondary shell; pt, prismatic thickening; S, septum.

Fig. 6 in Form and formation of flares and parabolae based on new observations of the internal shell structure in lytoceratid and perisphinctid ammonoids

Fig. 6. Internal structure of a secondary flare (median section, growth direction right) in Argonauticeras besairiei Collignon, 1949 (BSPG MAo- 1802) from Ambatolafia, Mahajanga Basin, NW Madagascar; Lower Albian, Cretaceous. Abbreviations: apc, apertural prismatic coating; dipl, dorsal inner prismatic layer; ipl, inner prismatic layer; ncl 1/2, nacreous layer of the primary/secondary shell; opl 1/2, outer prismatic layer of the primary/secondary shell; sb, shell bulge.

Fig. 2 in Form and formation of flares and parabolae based on new observations of the internal shell structure in lytoceratid and perisphinctid ammonoids

Fig. 2. Internal structure of flares (median section, growth direction right) in Argonauticeras besairiei Collignon, 1949 (BSPG MAo-1801) from Ambatolafia, Mahajanga Basin, NW Madagascar; Lower Albian, Cretaceous. A. Complete flare, the primary shell bends outwards and forms a frill. The flare ends in a backward reflection of the shell, i.e., apertural margin. Secondary shell material is attached from beneath and forms a prominent bulge in front of the flare. B. Close-up of A, contact of the primary shell and the secondary shell. The interior of the flares is covered by an apertural prismatic coating. C. Apertural margin of the flare, the primary shell wedges out. The primary outer prismatic layer and the apertural prismatic coating form a vanishing prismatic wedge. Abbreviations: apc, apertural prismatic coating; dipl, dorsal inner prismatic layer; ipl, inner prismatic layer; ncl 1/2, nacreous layer of the primary/secondary shell; opl 1/2, outer prismatic layer of the primary/secondary shell; sb, shell bulge; var, varix.

Fig. 5 in Form and formation of flares and parabolae based on new observations of the internal shell structure in lytoceratid and perisphinctid ammonoids

Fig. 5. Resorption process in flares of Lytoceratoidea. A. A complete flare with mantle cover. B. The retracting mantle begins resorption of shell material at the base of the flare. C. The mantle tissue rounds the flare stump through resorption. D. The retracted mantle begins secretion of secondary shell material. E. The mantle continues secreting the secondary shell. F. The mantle of the subsequent whorl begins to overgrow the flare stump of the preceding whorl. G. The mantle of the subsequent whorl overgrows the complete flare of the preceding whorl and begins its resorption. H. The mantle of the subsequent whorl resorbs the flare stump of the preceding whorl. I. The mantle of the subsequent whorl has smoothed the shell surface of the preceding whorl.