LOWER MIOCENE SHORE BIRD-LIKE FOOTPRINTS FROM THE EBRO BASIN, LA RIOJA, SPAIN: PALEOECOLOGICAL AND PALEOENVIRONMENTAL SIGNIFICANCE

IGNACIO DÍAZ MARTÍNEZ; OIER SUÁREZ-HERNANDO; BLANCA MARTÍNEZ-GARCÍA; JOSÉ MARÍA HERNÁNDEZ; SALVADOR GARCÍA FERNÁNDEZ; FÉLIX PÉREZ-LORENTE; XABIER MURELAGA

PALAIOS

SEPM-SOC SEDIMENTARY GEOLOGY

Lugar: Lawrence; Año: 2015 vol. 30 p. 424 - 431

0883-1351

Small shorebird-like footprints have been discovered in Cenicero (La Rioja,29 Spain). They are preserved in a sandstone block of the transition unit between the30 Nájera and Haro Formations from the Ebro Basin. This level is positioned in the31 Y2 local zone (MN2), of Agenian age (lower Miocene). The footprints are small,32 tridactyl or tetradactyl, with slender and proximally unconnected digit33 impressions. They have phalangeal pads and claw marks, and there is no evidence34 of a web or metatarsal pad. The footprints are compared with other shorebird-like35 ichnotaxa and assigned to the Cretaceous ichnotaxon Koreanaornis isp., which is36 herein identified for the first time in the Cenozoic. Other shorebird-like footprints37 from the upper Eocene to lower Miocene in the Ebro Basin and the lower Miocene38 ichnotaxa Aviadactyla media and Aviadactyla vialovi are also related to this39 ichnotaxon. In addition to the shorebird-like footprints, the Cenicero tracksite has40 invertebrate traces and sedimentary and organic structures typical of the Scoyenia41 ichnofacies, suggesting a mud-dominated floodplain in a central-distal alluvial42 fringe as the paleoenvironment. The morphology, habitat, and behaviour inferred43 from the shorebird-like footprints in the Cenicero tracksite are similar to other fossil footprints found in the Mesozoic and Cenozoic as well as to modern shore45bird tracks. This is likely due to morphological, ecological, and behavioral convergences among different avian clades from the Early Cretaceous to the present.