FIGURE 1. Map of the Sumidero Quarry showing the outcrops of the Sierra Madre Group outside Cristóbal de las Casas, Chiapas (based on Alvarado-Ortega and Than-Marchese 2012, fig. 1).
FIGURE 2. A view of the Sumidero Quarry, San Cristóbal de las Casas, Chiapas.
FIGURE 3. Thin-section and some microfossils of the fossiliferous miliolid mudstone from the Sumidero Quarry, San Cristóbal de las Casas, Chiapas. A) General view of IGML-525-Mi. B) Quinqueloculina sp., in IGML-526-Mi. C) Nezzazata sp., IGML-526-Mi. D) Globorotalites sp., in IGML-526-Mi. E) Triloculina sp. in IGML-528-Mi. F) Pseudobolivina sp., in IGML-525-Mi. G) Spiroplectammina sp., in IGML-527-Mi. All scales bars equal to 100µm.
FIGURE 4. IGM 14037 under UV light, Teoichthys brevipina from the Albian deposits of the Sumidero Quarry, San Cristóbal de las Casas, Chiapas, Mexico. Abbreviations: ao, antorbital; cl, cleithrum; dc, diplospondylus centrum; dfr, dorsal fin ray; ex, extrascapular; f, frontal; lj, lower jaw; na, nasal; op, opercle; pa, parietal; pfr, pectoral fin ray; pop, preopercle; r, rostral; smx, supramaxilla.
FIGURE 5. IGM 14038 transferred to resin and coated with magnesium, Notagogus novomundi from the Albian deposits of the Sumidero Quarry, San Cristóbal de las Casas, Chiapas, Mexico. Abbreviations: adfr 1-13, anterior-dorsal fin rays; bf, basal fulcra; c, centrum (ossified); cfr 1-14, caudal fin rays; cl, cleithrum; dsp, demosphenotic; ff, fringing fulcra; io, infraorbital; iop, infraopercle; mx, maxilla; na, nasal; pa, parietal; pdfr 1-13, posterior-dorsal fin rays; pfr 1-12, pectoral fin ray; pop, preopercle; ptt, posttemporal; r, rostral; sc, scutes; suo, supraorbital; red arrows show the rays of the anterior dorsal fin; violet arrows show the rays of the posterior dorsal fin.
FIGURE 6. IGM 14039 under white light, indeterminate fish of the family Pycnodontidae, from the Albian deposits of the Sumidero Quarry, San Cristóbal de las Casas, Chiapas, Mexico. Abbreviations: afp, anal fin pterygiophor; afr, anal fin ray; cl, cleithrum; df, dermocranial fenestra; dfp, dorsal fin pterygiophore; dfr, dorsal fin ray; dhy, dermalhyomandibula; dpt, dermopterotic; drs, dorsal ridge scute; dsoc, dermosupraoccipital; dsph, dermosphenotic; esc, extrascapular; fr, frontal; ha, hemal arcocenthrum; hs, hemal spine; io, infraorbital; mbs, modified bar-like scale; na, neural arcocenthrum; ns, neural spine; op, opercle; pa, parietal; pcb, postcoelomic bone; pcl, postcleithrum; pclvks, postcloacal ventral keel scute; pipvf, point of insertion of the pelvic fin; pop, preopercle; soc, supraoccipital; ubs, unmodified broad scale; vks, ventral keel scute; (l), paired element of the left side; (r), paired element of the right side; (v), ventral view.
FIGURE 7. IGM 14040 under white light, Belenostomus sp. from the Sumidero Quarry, San Cristóbal de las Casas, Chiapas, southeastern Mexico. Abbreviations: afr, anal fin ray; cl, cleithrum; d, dentary; dfr, dorsal fin ray; mfs, middle flank scale; pfr, pectoral fin ray; ptt, posttemporal, pvb, pelvic fin bone; pvfr, pelvic fin ray (displaced); q-lja, quadrate-lower jaw articulation; numbers show the vertical scale rows; op, opercle; or, orbit; sop, subopercle; black arrows on the head show the impression of the alveolar and ventral edges of the dentary bone.
FIGURE 8. IGM 14041 under white light, Thorectichthys sp. from the Sumidero Quarry, San Cristóbal de las Casas, Chiapas, southeastern Mexico. Abbreviations: afr, anal fin ray; cl, cleithrum; dfr, dorsal fin ray; op, opercle; pa, parietal; pd, predorsal bones, pds, predorsal scutes; pfr, pectoral fin ray; ppvs, postpelvic ventral scutes; prvs, prepelvic ventral scutes; pvfr, pelvic fin ray.
FIGURE 9. Diversity and geographic distribution of the North America Albian-early Cenomanian osteichthyan fishes. A) Map of the Late Albian showing the sites of the Albian and the Albian-Cenomanian boundary. B) Map of the early Cenomanian showing the fossil fish sites. C) Generic diversity in the range Albian-early Cenomanian showing the contribution of the Mexican sites (in red bars and line). D) The lagerstätten effect on fish diversity in the localities considered. E) The latitudinal effect on fish diversity in the localities considered. G) The interconnectivity effect of the North American seas over fish diversity in the localities considered. Abbreviations: CQ, El Chango Quarry; DM, Dragon Mountain; EQ, El Espinal Quarry; GRF, Glen Rose Formation; HR, Hay River; KF, Kiowa Formation; MF, Mowry Formation; MQ, Muhi Quarry; SQ, Sumidero Quarry; SR, Smoky River; TQ, Tlayúa Quarry; numbers above the bars indicate the number of fish genera in each respective case.
