Find research datasets worth reusing

opencc-by-4.0Sep 2019View details →

Fig. 2. Teleosauroid thalattosuchian Mystriosaurus laurillardi Kaup, 1834 in The mystery of Mystriosaurus: Redescribing the poorly known Early Jurassic teleosauroid thalattosuchians Mystriosaurus laurillardi and Steneosaurus brevior

Fig. 2. Teleosauroid thalattosuchian Mystriosaurus laurillardi Kaup, 1834 (NHMUK PV OR 14781, holotype of Steneosaurus brevior Blake, 1876, lower Toarcian of Whitby (Yorkshire, UK); skull in lateral (A1), dorsal (A2), and ventral (A3) views.

opencc-by-4.0Sep 2019View details →

Fig. 4 in The mystery of Mystriosaurus: Redescribing the poorly known Early Jurassic teleosauroid thalattosuchians Mystriosaurus laurillardi and Steneosaurus brevior

Fig. 4. Reconstruction of teleosauroid thalattosuchian Mystriosaurus laurillardi Kaup, 1834 cranium and mandible in dorsal (A1) and ventral (A2) view. The reconstructed portions are illustrated in SOM: fig. S6. Not to scale.

opencc-by-4.0Sep 2019View details →

Fig. 1. Teleosauroid thalattosuchian Mystriosaurus laurillardi Kaup, 1834 in The mystery of Mystriosaurus: Redescribing the poorly known Early Jurassic teleosauroid thalattosuchians Mystriosaurus laurillardi and Steneosaurus brevior

Fig. 1. Teleosauroid thalattosuchian Mystriosaurus laurillardi Kaup, 1834 (HLMD V946-948, holotype), lower Toarcian of Altdorf (southern Germany); skull in dorsal (A1) and lateral (A2) views, midsection of the skull in ventral view (A3), and of the mandible in dorsal view (A4).

Fig. 12 in Significance of intermediate forms in phyletic reconstruction of ammonites: Early Jurassic Phricodoceras case study

Fig. 12. Historical synthesis of the taxonomic interpretation for the genus Phricodoceras from 1826 until today. Six options are considered: H?, no taxonomic attribution or attribution deliberately left undetermined; Eo, explicit attribution to Eoderoceratoidea or implicit proximity with some ammonites currently attributed to the Eoderoceratidae; Ko, explicit attribution to the Kosmoceratidae; Ly, explicit attribution to the Lytoceratoidea (in the current sense); Ps, explicit attribution to the Psiloceratoidea and proximity with the Schlotheimiidae; La, enigmatic lazarus taxon. A cross indicates an absence of attribution to a taxon. A single black dot suggests an implicit or explicit but very reserved attribution. Two black dots suggest an explicit but debatable attribution. Three black dots suggest an unconditional explicit attribution. Four black dots suggest an explicit attribution based on ontogenetic evidence. For easy reading, the two columns corresponding to the two most frequent taxonomic interpretations (i.e., Eo and Ps) are shaded.

Fig. 11 in Significance of intermediate forms in phyletic reconstruction of ammonites: Early Jurassic Phricodoceras case study

Fig. 11. Habitus of some nodded, spined and/or tuberculate Lytoceratoidea (A) and Eoderoderatoidea (B–D). A. Analytoceras hermanni (Gümbel, 1861), Kammerkaralpe, Waidring, Tyrol, Austria, probably Late Hettangian (from Wähner 1894: pl. 3: 3a, b, modified), in ventral (A1) and lateral (A2) views. B. Epideroceras lorioli (Hug, 1899), St Peter's Field, Radstock, Somerset, UK, Echioceras raricostatum Chronozone, Paltechioceras aplanatum Subchronozone (from Edmunds et al. 2003: fig. 21. 4, modified), in lateral (B1) and apertural (B2) views. C. Tetraspidoceras repentinum Edmunds, 2009, St Peter's Field, Radstock, Somerset, UK, Uptonia jamesoni Chronozone, Phricodoceras taylori Subchronozone (from Edmunds 2009: pl. 32: 1, modified), in lateral (C1) and ventral (C2) views. D. Becheiceras bechei (Sowerby, 1821), Golden Cap, Seatown, Dorset, UK, Prodactylioceras davoei Chronozone, Oistoceras figulinum Subchronozone (from Edmunds 2009: pl. 38: 1, modified), in lateral (D1) and apertural (D2) views. Tubercles and/or spines in (t1) and/or (t2) positions of the Eoderoceratoidea (B–D) are not homologous with those of Phricodoceras, nevertheless this genus was long understood as a (borderline) member of this superfamily. In the case of Lytoceratoidea (A) the ornamental features in peri−siphonal position (pn3) are parabolic nodes which are morphologically clearly distinct from the tubercles or spines of both Eoderoceratoidea and Phricodoceras. The growth stage of the specimen is unknown.

Fig. 10 in Significance of intermediate forms in phyletic reconstruction of ammonites: Early Jurassic Phricodoceras case study

Fig. 10. Schematic representation and comparison of the ontogenies of an Angulaticeras macroconch (A. boucaultianum) and of a Phricodoceras macroconch (P. lamellosum) in a simplified diagram taking into account the assumed mobility (x−axis) and the assumed passive shell protection (y−axis). These parameters cannot be fully expressed quantitatively. Mobility depends mainly on hydrodynamic abilities, which are correlated with shell geometry but also with some aspects of ornamentation. Marked ornamental traits may play an important role. For example a keel or a ventral groove may increase the hydrodynamic stability of the shell and thereby facilitate mobility, but prominent tubercles and/or spines may significantly increase hydrodynamic drag thereby reducing mobility. Conversely the prominence of ornamentation (chiefly of tubercles and/or spines) may be an effective passive protection against predators. Although highly schematic and hypothetical, such a diagram can be understood as an approximate representation of an "adaptative landscape" in which successive growth stages can be roughly situated. This "adaptative landscape" can be divided into four quadrants labeled A–D. The two studied species occupy only quadrants A (rather poor mobility but good passive shell protection) and C (good mobility but poor passive shell protection). In fact, only the juvenile growth stages of Phricodoceras lamellosum are situated in quadrant A but all the other growth stages, of both species, are in quadrant C. This pattern underlines the adaptative peculiarity of the juvenile growth stages of Phricodoceras.

Fig. 8 in Significance of intermediate forms in phyletic reconstruction of ammonites: Early Jurassic Phricodoceras case study

Fig. 8. Septal suture lines of several Lytoceratoidea (A–D) and Eoderoceratoidea (E–H) for comparisons with those of the scholtheimiid ammonoids Angulaticeras and Phricodoceras (Fig. 7). A. Zaghouanites arcanum (Wiedenmayer, 1977) (from Rakús and Guex 2002: fig. 54e, modified). B. Eolytoceras tasekoi Frebold, 1967 (from Wiedmann 1970: text−fig. 9c, modified). C. Pleuroacanthites biformis (Sowerby in De La Beche, 1831) (from Canavari 1888: text–fig. 2.3, modified). D. Analytoceras gr. articulatum (Sowerby in De La Beche, 1831) (from Wiedmann 1970: text–fig. 8a, modified). E. Epideroceras planarmatum (Quenstedt, 1856) (from Schlatter 1980: beil. 15a, modified). F. Xipheroceras rasinodum (Quenstedt, 1884) (from Schlegelmilch 1976: 57, modified). G. Xipheroceras ziphus (Zieten, 1830) (from Schlegelmilch 1976: 56, modified). H. Eoderoceras bisbinigerum (Buckman, 1918) (from Schlegelmilch 1992: 62, modified). For each suture line the whorl height (wh) is indicated, if known. The main elements of the suture line are indicated by following abbreviations: E, external lobe; L, lateral lobe; U1, U2, umbilical lobes; I, internal lobe.

Fig. 7 in Significance of intermediate forms in phyletic reconstruction of ammonites: Early Jurassic Phricodoceras case study

Fig. 7. Septal suture lines of several Schlotheimiidae belonging to the genera Phricodoceras (A–E) and Angulaticeras (F–J). A. Phricodoceras urkuticum (Géczy, 1959) (from Géczy 1976: fig. 49, modified). B. Phricodoceras taylori (Sowerby, 1826) (from Dommergues 2003: fig. 6A, modified). C. Phricodoceras taylori (from Dommergues 2003: fig. 6B, modified). D. Phricodoceras taylori (from Schlegelmilch 1976: 61, modified). E. Phricodoceras gr. taylori (Sowerby, 1826) (from Schlatter 1990: fig. 3, modified). F. Angulaticeras martinischmidti (Lange, 1951) (from Schlegelmilch 1976: 38, modified). G. Angulaticeras charmassei (Orbigny, 1844) (from Schlegelmilch 1976: 38, modified). H. Angulaticeras densilobatum (Pompeckj, 1893) (from Schlegelmilch 1976: 39, modified). I. Angulaticeras lacunatum (J. Buckman, 1844) (from Schlegelmilch 1976, 38, modified). J. Angulaticeras rumpens (Oppel, 1862) (from Schlegelmilch 1976: 39, modified). For each suture line the whorl height (wh) is indicated, if known. The main elements of the suture line are indicated by following abbreviations: E, external lobe; L, lateral lobe; U1, U2, umbilical lobes; I, internal lobe.

Fig. 4 in Significance of intermediate forms in phyletic reconstruction of ammonites: Early Jurassic Phricodoceras case study

Fig. 4. Position and terminology of the tubercles, spines and/or bullae on Phricodoceras shells (juvenile and/or microconch. A, B. Normal view. C, D. Shaded view with indication of the main ornamental structure outlines (white lines). Abbreviations: t1, latero−umbilical position; t2, latero−ventral position; t3, peri−siphonal position; us, umbilical seam; vb, ventral band.

Fig. 3 in Significance of intermediate forms in phyletic reconstruction of ammonites: Early Jurassic Phricodoceras case study

Fig. 3. Microconch (m) / macroconch (M) dimorphism expressed by scholtheimiid ammonoid Phricodoceras exemplified by the NW Europe forms in the Uptonia jamesoni to Tragophylloceras ibex chronozones. A. Phricodoceras lamellosum (Orbigny, 1844) (M), UBGD 277451, Mazenay, Saône et Loire, France, probably early Uptonia jamesoni Chronozone, in apertural (A1), lateral (A2), and ventral (A3) views. B. Phricodoceras lamellosum (M), Kircheim unter Teck, Baden−Würtemberg, Germany, Early Pliensbachian (from Schlegelmilch 1976: pl. 27: 4, modified; original from Quenstedt 1884: pl. 28: 24), in apertural (B1), lateral (B2), and ventral (B3) views. C. Phricodoceras taylori (Sowerby, 1826) (m), Corbigny, Nièvre, France, Uptonia jamesoni Chronozone, Phricodoceras taylori Subchronozone (from Dommergues 2003: pl. 1: 4), in lateral view. D. Phricodoceras aff. cornutum (Simpson, 1843) (m), Fresnayle−Puceux, Calvados, France, Early Pliensbachian (from Dommergues et al. 2008: pl. 3: 6, modified), in ventral (D1) and lateral (D2) views. E. Phricodoceras taylori (m), Fresnay−le−Puceux, Calvados, France, Early Pliensbachian (from Dommergues et al. 2008: pl. 3: 5, modified), in ventral (E1) and lateral (E2) views. The two specimens corresponding to A, B are incomplete phragmocones (juvenile or immature shells) but the three corresponding to C–E are adult microconchs with the major part of the body chamber. The end of the phragmocone is starred. Notice the progressive ontogenetic transformation from tubercle (t3) to faint shoulder (s3) in specimen B. Abbreviations: t2, tubercle in latero−ventral position; t3, tubercle in peri−siphonal position; s3, shoulder peri−siphonal position.

Fig. 11 in A new pliosaurid from the Pliensbachian, Early Jurassic of Normandy, Northern France

Fig. 11. Cladogram showing the phylogenetic relationships of Cryonectes neustriacus gen. et sp. nov. Tree length: 133. CI = 0.52, RI = 0.63. For character list and taxa/ character matrix see SOM 1 and SOM 2. Bremer indices are indicated for each node.

Fig. 9 in A new pliosaurid from the Pliensbachian, Early Jurassic of Normandy, Northern France

Fig. 9. Pliosaurid plesiosaur Cryonectes neustriacus gen. et sp. nov., MAE2007.1.1(J), holotype; Late Pliensbachian, Early Jurassic, Calvados, France. A. Cervical vertebrae 1 to 5 in right lateral view. B. Vertebrae 1 to 5 in anterior view. C. Vertebrae 1 to 5 in ventral view.

Fig. 7 in A new pliosaurid from the Pliensbachian, Early Jurassic of Normandy, Northern France

Fig. 7. Pliosaurid plesiosaur Cryonectes neustriacus gen. et sp. nov., MAE 2007.1.1(J), holotype; Late Pliensbachian, Early Jurassic, Calvados, France. A. Skull in left lateral view. Posterior part of the right mandibular ramus in lateral (B) and lingual (C) views. Photographs (A1, B1, C1) and explanatory drawings (A2, B2, C2). D. Section of the right mandibular ramus (see Fig. 2 and 4 for actual line of section). E, F. Teeth.

Fig. 10 in A new pliosaurid from the Pliensbachian, Early Jurassic of Normandy, Northern France

Fig. 10. Pliosaurid plesiosaur Cryonectes neustriacus gen. et sp. nov., MAE2007.1.1(J), holotype; Late Pliensbachian, Early Jurassic, Calvados, France. A. Vertebrae 6 to 10 in right lateral view. B. Vertebrae 6 to 10 in anterior view. C. Vertebrae 6 to 10 in ventral view. D. An isolated neural arch in left lateral view.

Fig. 6 in A new pliosaurid from the Pliensbachian, Early Jurassic of Normandy, Northern France

Fig. 6. Pliosaurid plesiosaur Cryonectes neustriacus gen. et sp. nov., MAE 2007.1.1(J), holotype; Late Pliensbachian, Early Jurassic, Calvados, France. A. Rostrum in dorsal view. B. Close−up photograph of the parasphenoid and posterior interpterygoid vacuities. Close−up photograph of the anterior interpterygoid vacuity (C) and the posterior part of the palate in oblique anterior view (D). E. Rostrum in ventral view.

Fig. 5 in A new pliosaurid from the Pliensbachian, Early Jurassic of Normandy, Northern France

Fig. 5. Pliosaurid plesiosaur Cryonectes neustriacus gen. et sp. nov., MAE 2007.1.1(J), holotype; Late Pliensbachian, Early Jurassic, Calvados, France. Skull in ventral view (A) and explanatory drawing (B).

Fig. 3 in A new pliosaurid from the Pliensbachian, Early Jurassic of Normandy, Northern France

Fig. 3. Pliosaurid plesiosaur Cryonectes neustriacus gen. et sp. nov., MAE 2007.1.1(J), holotype; Late Pliensbachian, Early Jurassic, Calvados, France. Skull in dorsal view (A) and explanatory drawing (B).

Fig. 2 in A new pliosaurid from the Pliensbachian, Early Jurassic of Normandy, Northern France

Fig. 2. Nannofossil assemblages present in the matrix of the specimen Cryonectes neustriacus sp. nov., MAE 2007.1.1(J) from Upper Pliensbachian, Calvados, France. A, B. Thick specimens of Crepidolithus impontus. C. Thin specimen of Crepidolithus impontus. D. Parhabdolithus liasicus. E. Mitrolithus elegans. F. Crepidolithus crassus. G. Similiscutum cruciulus. H. Lotharingius frodoi. I. Calyculus sp. ind. Scale bars 5 µm.

Fig. 1 in A new pliosaurid from the Pliensbachian, Early Jurassic of Normandy, Northern France

Fig. 1. Simplified stratigraphic section of the Lower Jurassic succession in the Roche−Blain quarry (modified from Dugué et al. 1998), with the possible stratigraphic position of the specimen Cryonectes neustriacus MAE 2007. 1.1(J), holotype, as indicated by arrows. Abbreviations: P. spi., Pleuroceras spinatum Ammonite Zone; D. ten., Dactylioceras tenuicostatum Ammonite Zone; H. serp., Harpoceras serpentinus Ammonite Zone; H. v., Haugia variabilis Ammonite Zone; A.P., "Argile à poissons" formation; M., mudstone; W., wackestone; P., packstone; G, grainstone.