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FIG. 7. — Machaeracanthus goujeti n in Machaeracanthus goujeti n. sp. (Acanthodii) from the Lower Devonian of Spain and northwest France, with special reference to spine histology

FIG. 7. — Machaeracanthus goujeti n. sp.; Lower Devonian, Iberian Chain. Transverse section of middle part of spine MPZ 2010/958, juvenile: A, general view of upper longitudinal ridge, wing and pulp cavity; B, C, details of the hard tissues in the wing close to the central axis, showing lamellar dentine with growth increment and trabecular dentine with denteons; D, detail of centripetally growing trabecular dentine around the pulp cavity. Thin section observed in transmitted ordinary light. Abbreviations: see Material and methods Scale bars: A, 0.5 mm; B, D, 0.1 mm; C, 50 μm.

FIG. 9 in Machaeracanthus goujeti n. sp. (Acanthodii) from the Lower Devonian of Spain and northwest France, with special reference to spine histology

FIG. 9. — Scales of Machaeracanthus goujeti n. sp., Lower Devonian, Iberian Chain: A, B, element MGUV-15.075, Nogueras Fm, section Ni-2 (NI), in crown (A) and basal (B) views; C, D, element MGUV-15.077, Nogueras Fm., section Ni-2 (NI) in crown (C) and rostral (D) views; E, F, element MGUV-15.078, Nogueras Fm, section Ni-2 (NI), in crown (E) and rostral (F) views; G, element MPZ 2010/949, lateral view, Nogueras Fm., section Bco. Sur Sto. Domingo (ADRC); H, element MGUV-15.079, Nogueras Fm., section Bco. Sur Sto. Domingo (ADRC), basal view; I, element MGUV-15.080, Nogueras Fm., section Poyales-East (ADRC), crown view; J, element MGUV-15.082, Nogueras Fm., section Poyales-East (ADRC), crown view; K, element MGUV-15.081, Nogueras Fm., section Bco. Sur Sto. Domingo (ADRC), rostral view; L, element MGUV-15.076, Nogueras Fm, section Ni-2 (NI), anterior crown view. Scale bars: A-H, L, 500 μm; I-K, 250 μm.

FIG. 6. — Machaeracanthus goujeti n in Machaeracanthus goujeti n. sp. (Acanthodii) from the Lower Devonian of Spain and northwest France, with special reference to spine histology

FIG. 6. — Machaeracanthus goujeti n. sp.; Lower Devonian, Iberian Chain. Transverse section of distal part of spine MPZ 2010/955A, juvenile: A, general view; B, C, details of the upper longitudinal ridge. Arrows in C point to distal branches of dentinal tubules. Thin section observed in transmitted ordinary light. Abbreviations: see Material and methods. Scale bars: A, 0.5 mm; B, 0.1 mm; C, 50 μm.

FIG. 8. — Machaeracanthus goujeti n in Machaeracanthus goujeti n. sp. (Acanthodii) from the Lower Devonian of Spain and northwest France, with special reference to spine histology

FIG. 8. — Machaeracanthus goujeti n. sp.; Lower Devonian, Iberian Chain. Transverse section proximal part of spine MPZ 2009/27. A, general view of wing; B, detail of the wing (see framed area in A) showing trabecular dentine with taphonomic alteration; C, detail of B exhibiting the dentinal tubules. Thin section observed in transmitted ordinary light. Abbreviations: see Material and methods. Scale bars: A, 0.5 mm; B, 0.1 mm; C, 50 μm.

FIG. 3. — Machaeracanthus goujeti n in Machaeracanthus goujeti n. sp. (Acanthodii) from the Lower Devonian of Spain and northwest France, with special reference to spine histology

FIG. 3. — Machaeracanthus goujeti n. sp.; Lower Devonian, Iberian Chain; juvenile spine (morphotype 1) (MPZ 2010/950), Nogueras Fm., section Maripló (ADRC); Mpl26): A, upper surface view; B, lower surface view; C, trailing edge view. Arrows point to the distal end of wing and keel. Abbreviations: see Material and methods. Scale bar: 1 mm.

FIG. 5. — Machaeracanthus goujeti n in Machaeracanthus goujeti n. sp. (Acanthodii) from the Lower Devonian of Spain and northwest France, with special reference to spine histology

FIG. 5. — Machaeracanthus goujeti n. sp., Lower Devonian, Iberian Chain. Transverse sections of spines showing the development of pulp cavity and vascular pattern: A, distal part of spine MPZ 2010/955A, juvenile (morphotype 1), Nogueras Fm., Poyales-East (ADRC); B, middle part of spine MPZ 2010/958, juvenile (morphotype 1); C, proximal part of spine MPZ 2009/27 (morphotype 1), Nogueras Fm., Poyales-East; D, middle part spine MPZ 2010/959 (morphotype 2). Abbreviations: see Material and methods. Scale bars: 1 mm.

FIG. 2 in Machaeracanthus goujeti n. sp. (Acanthodii) from the Lower Devonian of Spain and northwest France, with special reference to spine histology

FIG. 2. — Synthetic columns of the axial depression of Nigüella (NI) (A) and of the axial depression of the Río Cámaras (ADRC) (B) with the distribution of the different types of remains attributed to Machaeracanthus goujeti n. sp. from the Lochkovian-Pragian strata of the Nogueras Fm. (modified from Valenzuela-Ríos & Botella 2000; Botella & Valenzuela-Ríos 2005).

FIG. 1. — A in Machaeracanthus goujeti n. sp. (Acanthodii) from the Lower Devonian of Spain and northwest France, with special reference to spine histology

FIG. 1. — A, Geographical setting of the studied area with indication of the distribution of Precambrian and Palaeozoic rocks in the Iberian Peninsula; B, geological map of Palaeozoic rocks in the Iberian chains pointing out the two studied areas (Devonian outcrops in black). Abbreviations: ADRC, axial depression of the Río Camaras (Carls 1988); NI, axial depression of Nigüella (Valenzuela-Ríos 1989).

Fig. 9 in Systematics of Snakes Referred to Dipsas variegata in Panama and Western South America, with Revalidation of Two Species and Notes on Defensive Behaviors in the Dipsadini (Colubridae)

Fig. 9. Dipsas oreas (Cope). A typically banded specimen from northern Peru (ANSP 31778). The snake is in a defensive posture (see under Defensive Behaviors in the Dipsadini).

Fig. 17 in Systematics of Snakes Referred to Dipsas variegata in Panama and Western South America, with Revalidation of Two Species and Notes on Defensive Behaviors in the Dipsadini (Colubridae)

Fig. 17. Defensive behavior of Sibon argus (AMNH 115927) from 600 m on the continental divide north of El Cope´, Cocle´, Panama. Top: The head is widened when mildly disturbed. Bottom: When further harassed, the snake coiled its body into a symmetrically raised spring, keeping its head hidden in the center.

Fig. 21 in Systematics of Snakes Referred to Dipsas variegata in Panama and Western South America, with Revalidation of Two Species and Notes on Defensive Behaviors in the Dipsadini (Colubridae)

Fig. 21. The final stage of defensive behavior in Dipsas nicholsi—a raised coil narrowest at the top, with the head exposed. Over a period of several days, this snake consistently coiled in the same direction (counterclockwise following the coils from above). See figure 1 for another view of the same specimen.

Fig. 5 in Systematics of Snakes Referred to Dipsas variegata in Panama and Western South America, with Revalidation of Two Species and Notes on Defensive Behaviors in the Dipsadini (Colubridae)

Fig. 5. Dipsas nicholsi (Dunn) from Madden Forest, central Panama. Left: KU 110311 in dorsal and ventral view. Right: KU 110312, above; KU 110313, below.

Fig. 1 in Systematics of Snakes Referred to Dipsas variegata in Panama and Western South America, with Revalidation of Two Species and Notes on Defensive Behaviors in the Dipsadini (Colubridae)

Fig. 1. Dipsas nicholsi (Dunn), a snaileater endemic to central Panama. Top: A specimen (not collected) photographed in 1974 in the Madden Forest Preserve, by Harry W. Greene. Bottom: Another specimen from Madden Forest, this one in a final stage of defense posturing (see figs. 20–21), photographed in 1966 by C.W. Myers.

Fig. 3 in Systematics of Snakes Referred to Dipsas variegata in Panama and Western South America, with Revalidation of Two Species and Notes on Defensive Behaviors in the Dipsadini (Colubridae)

Fig. 3. Dipsas variegata (Duméril, Bibron, and Duméril). Representative specimens in dorsal and ventral view. Left: D. v. variegata from Rancho Grande, Venezuela (FMNH 204479, 468 mm SVL). Right: D. v. trinitatis from near Asa Wright Nature Center, Trinidad (FMNH 217217, 419 mm SVL).

Fig. 13 in Systematics of Snakes Referred to Dipsas variegata in Panama and Western South America, with Revalidation of Two Species and Notes on Defensive Behaviors in the Dipsadini (Colubridae)

Fig. 13. Dipsas andiana (Boulenger) in dorsal and ventral view. Left: Specimen from Bolívar Province, Ecuador (KU 132503). Right: Specimen from Pichincha province, Ecuador (MCZ 166543).

Fig. 2 in Systematics of Snakes Referred to Dipsas variegata in Panama and Western South America, with Revalidation of Two Species and Notes on Defensive Behaviors in the Dipsadini (Colubridae)

Fig. 2. Variation in dorsal head patterns of Dipsas variegata (Duméril, Bibron, and Duméril). From top to bottom: AMNH 111075 (Bolívar, Venezuela), AMNH 137584 (Trinidad), AMNH 21275 (Guyana), AMNH 114769 (Bolívar, Venezuela). The cephalic color pattern of Dipsas variegata, which varies from indistinct to blotched, lacks the distinctive Πshaped marking that characterizes D. nicholsi and D. andiana (cf. figs. 4, 8).

Fig. 15 in Systematics of Snakes Referred to Dipsas variegata in Panama and Western South America, with Revalidation of Two Species and Notes on Defensive Behaviors in the Dipsadini (Colubridae)

Fig. 15. Dipsas andiana (Boulenger). A specimen of unknown locality (AMNH 79013) with an atypical head pattern. See text.

Fig. 19 in Systematics of Snakes Referred to Dipsas variegata in Panama and Western South America, with Revalidation of Two Species and Notes on Defensive Behaviors in the Dipsadini (Colubridae)

Fig. 19. Complex defensive behavior in Sibynomorphus mikanii. Top: The head is raised and widened, and the body is inflated, especially obvious at the widened neck (which approaches the dorsoventral hood formation of some snakes). Middle: After continued provoking, the snake has deflated the body and arranged itself into a loose asymmetrical coil or ball, with its head hidden. Bottom: An alternative coil at another time, with the head almost hidden.

Fig. 20 in Systematics of Snakes Referred to Dipsas variegata in Panama and Western South America, with Revalidation of Two Species and Notes on Defensive Behaviors in the Dipsadini (Colubridae)

Fig. 20. Initial stages in the defensive coiling of Dipsas nicholsi (KU 110313). Top: Beginning formation of an anterior coil (stage 1). Bottom: Anterior coil complete, posterior coil initiated (stage 2). See text for behavioral sequence in which stage 2 above is replaced by abrupt whipping motions while retaining the forward coil. See figure 21 for stage 3, in which the snake has gathered itself into a single coil.

Fig. 16 in Systematics of Snakes Referred to Dipsas variegata in Panama and Western South America, with Revalidation of Two Species and Notes on Defensive Behaviors in the Dipsadini (Colubridae)

Fig. 16. Head widening (triangulation)—the temporary acquisition of triangular head shape by spreading the jaw articulations—a common defensive trait among the Dipsadini and some other snakes. This behavior can also be seen in figures 9 and 17–19. Top: Dipsas viguieri from lowland Madden Forest, central Panama (KU 110317). Bottom: Dipsas temporalis from cloud forest on ridge between Río Jaqué and Río Imamadó, 800– 890 m, Darién, Panama (specimen one of KU 110294–110297).