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Figure 4 in Histological study of the oral teeth and their bony support in the Mexican Jurassic gar †Nhanulepisosteus mexicanus (Ginglymodii, Lepisosteidae)

Figure 4. – †Nhanulepisosteus mexicanus. A-B: IGM 4902-5. Cross-section (respectively natural and polarized transmitted light) of a small tooth. We can show a crown of dentine (de), with an external crenulated layer of enameloid (arrow-heads). The pulp cavity (pc) is empty and its wall is regular. Scale bar = 100 μm.

Figure 2 in Histological study of the oral teeth and their bony support in the Mexican Jurassic gar †Nhanulepisosteus mexicanus (Ginglymodii, Lepisosteidae)

Figure 2. – †Nhanulepisosteus mexicanus: External view of the sample used for the paleohistological study (IGM 4902). (see Material and Methods chapter for explanations). Scale bar = 5 mm.

Figure 1 in Histological study of the oral teeth and their bony support in the Mexican Jurassic gar †Nhanulepisosteus mexicanus (Ginglymodii, Lepisosteidae)

Figure 1. – †Nhanulepisosteus mexicanus: External view of the fossil sample (IGM 4901) showing four caniniform teeth with their apical cap of acrodine (arrows). Two small teeth are seen between the fangs (arrowheads). Scale bar = 1 mm.

Figure 7 in Histological study of the oral teeth and their bony support in the Mexican Jurassic gar †Nhanulepisosteus mexicanus (Ginglymodii, Lepisosteidae)

Figure 7. – Comparison of the pulp cavity of the fang teeth in four Lepisosteoidei. Cross sections are made in the mid part of the teeth. A: †Nhanulepisosteus mexicanus (specimen IGM 4902; see Brito et al., 2017). B: †Atractosteus sp.* from the Santonian of Hungary (specimen VER 2014.91.3). C: Atractosteus tropicus. D: Lepisosteus platostomus (See fig. 3C in Meunier and Brito, 2017) The pulp cavity is completely invaded by the dentigerous tissue in †N. mexicanus and in the Santonian †Atractosteus whereas the dentine plies let at least the central mid part in the two extant species. The tooth of †Atractosteus sp. has eusthenodont plicidentine whereas teeth of Atractosteus tropicus and Lepisosteus platostomus have polyplocodont plicidentine. Abbreviations: de: dentine; en: collar enamel; er: external ridges; pc: pulp cavity; rd: radial folding of the dentine; vs: vascular space; arrowheads: dentine folds. Scale bars: A, D = 250 μm; B = 500 μm; C = 150 μm * The photo of the ground section was given to us by Dr. Marton Szabó, Department of Paleontology and Geology, Hungarian Natural History Museum, Ludovika têr 2, Budapest 1083, Hungary.

Figure 6 in Histological study of the oral teeth and their bony support in the Mexican Jurassic gar †Nhanulepisosteus mexicanus (Ginglymodii, Lepisosteidae)

Figure 6. – †Nhanulepisosteus mexicanus: Histological organization of the teeth supporting bone. A: Detail of the basal contact of a tooth (pc) and its supporting bone (bo) with vascular canals or cavities (vc). The white arrows point to osteons. B: Detail of the dentigerous plate showing lamellar bone and numerous cementing lines (black arrow-heads) that characterized an intensive remodeling of bone tissue below the tooth. We also show canalicles of Williamson (arrows). The asterisks point to secondary osteons. C-D: Detail of the secondary osteon (**) of Fig. 6B (respectively natural and polarized transmitted light). The secondary bone of the osteons is lamellar bone (black asterisks). The arrow-heads point to cementing line. We also show canalicles of Williamson (black arrows). E: Detail of the secondary osteon (*) of Fig. 6B showing canaliculi of Williamson (black arrows) and osteocytes (black arrowheads). A: IGM 4902-4; B, C, D, E: IGM 4902- 5. Scale bars: A = 200 μm; B = 100 μm; C, D = 50 μm; E = 25 μm.

Figure 5 in Histological study of the oral teeth and their bony support in the Mexican Jurassic gar †Nhanulepisosteus mexicanus (Ginglymodii, Lepisosteidae)

Figure 5. – †Nhanulepisosteus mexicanus: A: Pharyngeal dentigerous plate. We can see cross (white and black arrow-heads) and axial (white and black arrows) sections of minute teeth. We can also see a section of a scale (sc) (bo = bony tissue). B: Axial section of a pharyngeal tooth (white arrow) and its supporting bony plate (bp). A: IGM 4902-4; B: IGM 4902-5. Scale bars: A = 200 μm; B = 100 μm.

Figure 3 in Histological study of the oral teeth and their bony support in the Mexican Jurassic gar †Nhanulepisosteus mexicanus (Ginglymodii, Lepisosteidae)

Figure 3. – †Nhanulepisosteus mexicanus: Histological organization of the fangs (natural transmitted light). A: Axial section of a tooth. The pulp cavity (pc) is totally occupied by axial trabeculae of dentine (de) alternating with pulp spaces. The tooth is fixed on a basement of reconstructed bone (bo). vc = vascular cavities. B-D: Three cross-sections of different levels of a tooth. B: The section is localized at the tooth base; it shows a ridged crown of orthodentine surrounded by a thin layer of enameloid (en). The pulp cavity is occupied by vascularized dentine. On the bottom of the fig, the bone of attachment (bo). C: The section crosses the mid part of the pulp cavity. The tooth is constituted of a crown of orthodentine (de) surrounded by a layer of enamel (en) showing external crests. The pulp cavity is totally occupied by vascularized dentine. D: The section is in the higher part of the pulp cavity. The tooth is constituted of a crown of orthodentine (de) surrounded by the crenulated enamel (en). We can see the pulp cavity which is reduced. E: Cross-section in the mid part of the tooth. Details of the dentine showing the peripheral orthodentine layer (white asterisks), with its ondontoblastic canalicles and the vascular canals fit together. Each canal is surrounded by orthodentine (black arrow-head). The enameloid layer is crenulated (white arrow-heads). A: IGM 4902-5; B: IGM 4902-3; C,E: IGM 4902-2; D: IGM 4902-1. Scale bars: A, B, C = 200 μm; D = 100 μm; E = 50 μm.

Figure 3. – Lepisosteus platostomus. Left jaw. A in Histological characteristics of lower jaw bones and oral teeth of the short nose gar, Lepisosteus platostomus Rafinesque, 1820 (Lepisosteidae)

Figure 3. – Lepisosteus platostomus. Left jaw. A: Axial section of a caniniform tooth showing the apical cap of acrodin (ac) above the dentine cone (de), the collar enamel (en) that covers the tooth shaft, the dentine folds in the pulp cavity (pc), and the coronoid bone (cb). Scale bar = 500 μm. B: Detail of the apex of the tooth showing the odontoblastic canaliculi (arrow). Scale bar = 20 μm. C: Transverse section of a caniniform tooth showing the external ridges (arrows) and the dentine folds (arrowheads) in the pulp cavity (pc). The dentine is overlain by a thin collar enamel (en) covering the tooth shaft and participating in the folds. Scale bar = 100 μm. D: The section crosses through three small lingual teeth that show minute folds in their pulp cavity. A caniniform tooth can be seen at the bottom left. Scale bar = 50 μm.

Figure 2. – Lepisosteus platostomus. A in Histological characteristics of lower jaw bones and oral teeth of the short nose gar, Lepisosteus platostomus Rafinesque, 1820 (Lepisosteidae)

Figure 2. – Lepisosteus platostomus. A: External view of the left lower jaw showing the caniniform teeth on the labial side of the jaw. The largest tooth (arrow) is located at the anterior tip of the jaw. On the lingual side of the jaw there are small sharp teeth (arrowheads). Scale bar = 5 mm. In the inset a detail of a caniniform tooth showing the external ridges at its base (arrowhead). Scale bar = 1 mm. B-D: Right jaw. B: Cross section of the jaw (microradiograph) showing five small teeth inserted on a coronoid bone (upper left) plus a larger tooth on the dentary. The white asterisk indicates the unmineralized Meckel's cartilage on the left hand side of the dentary (de). Scale bar = 2.5 mm. In the inset a microradiograph of a caniniform tooth and its attachment bone (bo), also showing its dentine core (arrowhead) with the apical acrodin cap (arrow). C: Parasagittal median section of the jaw (microradiograph) showing five caniniform teeth. The dentine folds occupy the total height of the pulp cavities. On the left one can also see five hypermineralized acrodin caps. Scale bar = 2 mm. D: Parasagittal lingual section of the jaw (microradiograph) showing the small lingual teeth series some of them showing minute mineralized folds in the pulp cavity. Scale bar = 1 mm.

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Figure 4. – Lepisosteus platostomus. A-C in Histological characteristics of lower jaw bones and oral teeth of the short nose gar, Lepisosteus platostomus Rafinesque, 1820 (Lepisosteidae)

Figure 4. – Lepisosteus platostomus. A-C: Lower right jaw, transverse sections, natural transmitted light. A: Dentary. Primary bone with canaliculi of Williamson is dominating but with some areas of secondary bone around some vascular cavities. A patch of multilayered ganoine is seen (white asterisk) and the white arrowheads point to small secondary vascular canals. Scale bar = 50 μm. B: Detail of the inset 1 of Fig. 4A showing primary bone (bo) and secondary bone (black asterisks) with canaliculi of Williamson (arrowheads) present in the two types of bone tissues. Scale bar = 50 μm. C: Detail of the inset 2 of Fig. 4A showing several ramified canaliculi of Williamson (arrowheads). Scale bar = 50 μm. D: Scale. Transverse section, natural transmitted light. The bony basal plate (bp) shows the canaliculi of Williamson that are relatively parallel and with very few branchings. (G = ganoine). Scale bar = 200 μm. E: Coronoid bone. Detail of bony tissue showing several osteocytes (arrows) with their canaliculi. Scale bar = 10 μm. F: Coronoid bone. Detail of the base of a tooth (de) showing attachment bone (ab), primary bone (bo) and a vascular canal (vc) surrounded by secondary bone that is discordant (arrowheads) relatively to the primary bone. Scale bar = 5 μm.

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Figure 1 in Histological characteristics of lower jaw bones and oral teeth of the short nose gar, Lepisosteus platostomus Rafinesque, 1820 (Lepisosteidae)

Figure 1. – Lepisosteus platostomus. Tomographic image of a fang (black asterisk), and a mid-sized caniniform teeth (white asterisk) in the anterior part of the left lower jaw. The tridimensional reconstruction of the dentary bone and teeth shows three folds in the internal wall of the fang (arrows), which occupy two thirds of the pulp cavity. The space indicated by arrows between the narrow walls of each fold corresponds to external area of the tooth due to the synchronized folding of both the dentine and the collar enamel. The pulp cavity of the second tooth also shows two folds (arrowheads) along the vertical axis of the shaft. Scale bar = 500 μm. (from Germain et al., 2016: fig. 1).