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The Los Cayos dinosaor tracksite is located at the eastern sector ofthe Cameros Basin (Cornago Township, La Rioja province), NE Spain. The sediments consist of interbedded terrigenoos siliciclastics and carbonates belonging to the Enciso Groop (Early Cretaceoos, Aptian in age). The sedimentological and faonal evidence soggests that these sediments were deposited in a low gradient lacostrine environment.Los Cayos constitotes a relatively wide area with at least 6 localities that have yielded dinosaor tracks. More than 2,000 dinosaor tracks have been discovered to date. Mediom to large theropod dinosaors constitote aboot 95% of the ichnofaona. Ornithopod dinosaor tracks have been reported from only one of the ootcrops (Los Cayos D). Los Cayos S has yielded theropod and saoropod tracks. One saoropod trackway shows a narrow-gaoge locomotion pattern and a manos print morphology soggesting that the trackmaker was a titanosaorid, or at least a titanosaoriform saoropod. Sorne pterosaor manos impressions, avian-like footprints of small size and possible tortle tracks complete the assemblage of one of the most impressive and best-preserved dinosaor tracksites of the Eoropean Lower Cretaceoos.

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RESUMENSe describen 3 nuevos yacimientos de icnitas de Dinosaurios en el Cretácico inferior (Hauteriviense) de La Rioja: Valdeté, La Magdalena (ambos en el término de Préjano) y Muro de Aguas. La morfología y tamaño de las buellas sugiere que ban sido causadas por al menos 3 diferentes tipos de dinosaurios Iguanod6ntidos. Las ienitas de La Magdalena fueron producidas por un gran Ornit6podo graviportal desconocido osteol6gicamente. Su morfotipo indica un máximo desarrollo de este carácter dentro del conjunto de dinosaurios bípedos (Ornit6podos o Ter6podos). En el caso de los Ornit6podos, la graviportalidad es un estadio estructural derivado a partir de una forma relativamente más grácil, tridáctila y mesax6nica.Con respecto al cálculo de la velocidad que indican las trazas, la estimaci6n de la altura de la extremidad (h) ha sido realizada por medio de un análisis estadistico dentro de diversos esqueletos de Iguanod6ntidos conocidos. Las estimaciones de velocidad obtenidas presentan valores comunes en Ornit6podos de media y gran talla.Se han descrito, hasta la fecha, al menos 10 morfotipos ienológicos de dinosaurios en la wna de la Rioja Baja y norte de Soria (4 Omit6podos, 2 Ter6podos, l Coelurosaurio y 2 Saur6podos). Palabras clave: IcnitJJs de dinosaurios, cretácico inferior, EspaíJa. ABSTRAerTbree new Early Cretaceous (Hauterivian) dinosaur footprints outcrops are reported from La Rioja: Valdeté, La Magdalena (townsbip of Préjano) and Muro de Aguas. Tbe morpbology and size of tbe footprints suggest that tbe track-makers are tbree different iguanodontids at least. Tbe footprints from La Magdalena were printed by a graviportal ornithopod osteologically unknown. Tbat morphotype shows a maximun development of graviportality within the biped dinosaurs (omithopods or tberopods). Witbin omithopod dinosaurs graviportality is a derived structural state from a relatively slender, tridactyl, mesaxonic formoRespect to the estimation of speed of the track-makers, tbe height of the limb (b) has been calculated by means of an statistical analysis within tbe osteological material of several iguanodontids. Tbe speed values are the common ones reported within medium and great sized ornitbopods.Ten dinosaur footprint morpbotypes, at least, bave been reported from La Rioja Baja and the Nord area of Soria, up to now (four medium-great sized ornithopods, one small sized ornithopod, two tberopods, one coelurosaur and two sauropods).