Dinosaur tracks have been identified near San Martín Atexcal, southern Puebla, Mexico, within the sedimentary sequence of the San Juan Raya Formation of Lower Cretaceous (Albian) age. The tracksite, located in the bed of the Magdalena River, reveals six different ichnofossiliferous levels identified within a 9 m thick sedimentary sequence. The inferred environment is that of a tidal (marginal marine) mudflat (Level I). Level I preserves three theropods trackways (?Allosauroidea), additionally, isolated tracks belonging to iguanodontids (Ornithopoda). Level II preserves faint iguanodontid tracks. Levels III to V preserve sauropod tracks. Younger level VI preserves, although morphologically different, a track belonging to Ornithopoda. The dinosaur tracks from San Martín Atexcal support the existence of continental facies within the San Juan Raya Formation; they represent the second record of dinosaur tracks from the Lower Cretaceous of Mexico and are part of an important but little documented record of Lower Cretaceous dinosaurs in Mexico. 1. Introduction Since the first report on dinosaur tracks from Mexico, the number of reported localities has increased considerably [1–3]. To date, this record includes three reports of Jurassic dinosaur tracks, plus several dinosaur tracks and trackways of Late Cretaceous dinosaurs; most of these localities are distributed from the central through northern parts of the country [3]. However, the evidence of Mexican dinosaurs of Lower Cretaceous age is now restricted to the site reported here (see [3, 4]). This track site is located near the small town of San Martin Atexcal in southern Puebla, central Mexico (Figure 1), and it represents the first known dinosaur track site of this age from Mexico. Two other small outcrops, recently discovered, reveal more dinosaur tracks within the San Juan Raya Formation; however, these remain unstudied. Figure 1: Geographic location of the State of Puebla (a) in central Mexico and the Lower Cretaceous dinosaur track site near San Martin Atexcal, Puebla (b). The locality is indicated by the asterisk. The site herein reported reveals dinosaur tracks in at least six different stratigraphic levels in the upper part of the San Juan Raya Formation. The objective of this paper is to document this dinosaur track site, to comment on the observed ichnofaunal succession, and place the information regarding the tracks in the broader context of the Lower Cretaceous dinosaur paleoichnology. 2. Study Area and Geological Context This Lower Cretaceous dinosaur tracksite is located in southern Puebla,
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