FIGURE 1. Map of the Belisario Domínguez quarry, near Palenque, Chiapas, southeastern Mexico. Yellow areas into the map show the Paleocene Tenejapa-Lacadón geological unit.

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FIGURE 2. Eekaulostomus cuevasae gen. and sp. nov. from the Danian marine deposits of the Belisario Domínguez quarry, near Palenque, Chiapas, southeastern Mexico. 1, General view of IGM 4716, holotype and single specimen known. 2, Idealized line drawing of the same specimen.

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FIGURE 3. Head and anterior part of the trunk of Eekaulostomus cuevasae gen. and sp. nov. from the Belisario Domínguez quarry. 1, General view of the head of specimen IGM 4716. 2, Line drawing of 1. Abbreviations: aa, anguloarticular; br, branchiostegals; cl, cleithrum; den, dentary; eccor, ectocoracoid; ecp, ectopterygoid; fr, frontal; hy, hyomandibula; iop, interopercle; la, lachrymal; le, lateral ethmoid; mes, mesethmoid; mx, maxilla; op, opercle; pa, parasphenoid; pal, palatine; pmx, premaxilla; pop, preopercle; pvfr, pelvic fin rays; q, quadrate; sc, scutes; sop, subopercle; sy, symplectic; v, vertebral centra; vo, vomer (the rays of pelvic fin are seen below the cleithrum).

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FIGURE 4. Unpaired and caudal fins of Eekaulostomus cuevasae gen. and sp. nov. from the Belisario Domínguez quarry. 1, General view of the head of specimen IGM 4716. 2, Idealized line drawing of 1. Abbreviations: afs, anal fin spines; afr, anal fin rays; dfr, dorsal fin rays; dfs, dorsal fin spines; pr, procurrent rays; black arrows enclose the principal rays of caudal fin.

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FIGURE 5. Scutes of Eekaulostomus cuevasae gen. and sp. nov. from the Belisario Domínguez quarry. 1, Close-up of the head of specimen IGM 4716, showing a scute with the external surface exposed. 2, Idealized line drawing of 1. 3, Close-up of the caudal region of the specimen IGM 4716, showing a scute with the internal surface exposed.

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FIGURE 6. Phylogenetic relationships of Eekaulostomus cuevasae gen. and sp. nov. and the superfamily Aulostomoidea within the order Gasterosteiformes (modified from Keivany and Nelson, 2006) (check the characters supporting the nodes in Table 2; number near the nodes show the bootstrap values obtained above 50%).

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FIGURE 7. Geographical and temporal distribution of fossil and recent members of the superfamily Aulostomoidea, including Eekaulostomus cuevasae gen. and sp. nov. from the Belisario Domínguez quarry, near Palenque, Chiapas, southeastern Mexico.

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