FIGURE 1. Map of Yosobé and La Lobera, near Tlaxiaco, Oaxaca, Mexico.

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FIGURE 2. Map of the Tlaxiaco Basin and distribution of the vertebrate fossil localities and areas reported before the present manuscript. 1, Cerro de la Virgen; 2, Petlalcingo area; 3, Wieland´s area; 4, Amoltepec area; 5, Papalutla; 6; La Lobera; 7, Yosobé (6 and 7 are new localities reported in the present paper).

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FIGURE 3. Geologic map of Tlaxiaco showing the position and shape Yosobé and La Lobera localities (modified from SGM 2000a, 2000b, 2009).

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FIGURE 4. Geologic map and lithostratigraphical column of Yosobé. M, Marl stratum; L1-L8, limestone strata; the intermediate strata (L1-L2, L2-L3,... L7-L8) are the bituminous shales layers that carry the vertebrate assemblage of Yosobé.

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FIGURE 5. Yosobé locality. 1, general view of this locality showing the limestone layers (arrows) and fossil-bearing shale strata (between the arrows), and part of the village of Tlaxiaco in background. 2, bituminous and fossiliferous shale layers at Yosobé with some nodules in situ (arrows).

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FIGURE 6. Planohybodus sp. from Yosobé; 1, isolated and fragmented tooth, specimen IGM 9316. 2-5, fragment of a dorsal spine in anterior (2), lateral (3), posterior (4), and cross-section (5) views, specimen IGM 9317. Arrow indicates the anterior edge of the predorsal spine.

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FIGURE 7. Gyrodus sp., specimen IGM 9318 from Yosobé. 1, general view. 2, close up of possible vomerine teeth. Abbreviations: dsoc, dermosupraoccipital; fr, frontal; hm, hyomandibular; op, opercle; pa, parietal; pop, preopercle; s, scale; sc, sclerotic.

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FIGURE 8. Jurassic remains of Ginglymondi fishes from localities near Tlaxiaco. 1-4, Scheenstia sp., specimen IGM 9320 from Tithonian strata of La Lobera, including a group of disarticulated scales (1), isolated scale (2), and a possible fragment of a vomer with teeth (in ventral view and lateral view, 3 and 4, respectively). 5, isolated scale of an undetermined Lepisosteiform described here as Morphotype 1, specimen IGM 9321 from Kimmeridgian strata of Yosobé. 6-7, scales of both sides of the body of an undetermined Lepisosteiform described here as Morphotype 2, specimen IGM 9322 from Kimmeridgian strata of Yosobé. Abbreviations: adp, anterior dorsal process; avp, anterior ventral process; dp, dorsal process; arrows indicate the anterior edge of the scales.


FIGURE 9. Trunk remains of a Pleuropholidae fish, specimen IGM 9323 from Yosobé. Abbreviations: fsc, body-flak scales; rsc, rhomboidal scales.

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FIGURE 10. Vertebrates of marine reptiles from Yosobé. 1-3, Specimen IGM 9324, undetermined thalattosuchian crocodyliform in anterior (1), dorsal (2), and lateral (3) views. 4-6, Specimen IGM 9325, undetermined ophtalmosaurid ichthyosaur in anterior (4), dorsal (5), and ventral (6) views. In both specimens the arrows show the anterior direction. Abbreviations: dp, diapophysial process; fna, facet for the neural arch; ias, intervertebral articular surfaces; ncf, neural canal floor; ncs, neurocentral suture; nf, nutritive foramen; ns, neural spine; pz, posterior zygapophysis.

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