TABLE 1. Measurements of the bird footprints of Lerín Formation. Abbreviations: FL, footprint length; FW, footprint width; cpLxW, central pad length and width; II, digit II length; III, digit III length; IV, digit IV length; II^III, angle between digits II and III; III^IV, angle between digits III and IV; II^IV, angle between digits II and IV; PL, pace length. All parameters are given and compared in millimeters, except for II^III, III^IV, and II^IV, which are in degrees.

  FL FW cpLxW II III IV II^III III^IV II^IV PL
AG1-1 136 174 30x20 62 94 80 60 66 126 -
AG1-2 130 - 25x- - 98 80 - 70 - -
AG1-3 - - - - - - - - - -
AG2-1.1 121 164 25x25 58 90 70 68 70 138 -
AG2-1.2 120 - 25x20 - 90 78 - 76 - 400
AG3-1.1 123 157 24x28 50 92 72 58 58 116 -
AG3-1.2 124 - - 44 86 - 58 - - 470
AG3-2 154 178 28x30 55 112 78 74 76 150 -
AG3-3 140 - 25x26 66 95 - 63 63 126 -
AG3-4 124 156 20x22 55 94 70 61 67 128 -
AG4-1 125 190 20x25 65 92 82 58 78 136 -
AG4-2 - 172 - 60 100 - 59 72 131 -
Mean 130 170 25x25 57 95 76 62 70 131 -

TABLE 2. Avian fossil record from the early Miocene in the Iberian Peninsula. All the information is extracted from Sánchez-Marco (1999, 2006), Mlíkovský (2002), Grellet-Tinner et al. (2012), and Díaz-Martínez et al. (2015). Only the most recent taxonomic/ichnotaxonomic determination is considered.

Taxon/ichnotaxon Zone Locality (province) Reference
Koreanaornis isp. MN 1- MN 3 Los Arcos (Navarra) Díaz-Martínez et al. (2015)
Aves indet. MN 2 Navarrete (Teruel) Adrover (1975)
Gruipeda cf. máxima MN 2 Cenicero (La Rioja) Díaz-Martínez et al. (2011)
Uvaichnites riojana MN 2 Cenicero (La Rioja) Díaz-Martínez et al. (2012)
Koreanaornis isp. MN 2 Cenicero (La Rioja) Díaz-Martínez et al. (2015)
Uvaichnites riojana MN 2 Aguilares (Navarra) In this work
Plesiocathartes? gaillardi MN 3 El Fallol (Barcelona) Crusafont and Villalta (1955)
Phoenicopteridae indet. MN 3 Bardenas Reales (Navarra) Murelaga (2000)
Phoenicopteridae indet. MN 3 Bardenas Reales (Navarra) Grellet-Tinner et al. (2012)
Palaeortyx edwardsi MN 4 Can Mas (Barcelona) Villalta (1963)
Miophasianus altus MN 4 Can Mas (Barcelona) Sánchez-Marco (2006)
Aves indet. MN 4 Alto de Ballester (Teruel) Sánchez-Marco (1999)
Aves indet. MN 4 La Retama (Cuenca) Sánchez-Marco (1999)
Aves indet. MN 4 Estación Imperial (Madrid) Sánchez-Marco (1999)
Aves indet. MN 4 La Artesilla (Zaragoza) Sánchez-Marco (1999)
Miophasianus sp. MN 4 Córcoles (Guadalajara) Alférez et al. (1982)
Aves indet. MN 4 Els Casots (Barcelona) Sánchez-Marco (1999)
Large bird tracks MN 4- MN6 Salinas de Añana (Álava) Antón et al. (1993)
Small bird tracks MN 4- MN6 Salinas de Añana (Álava) Antón et al. (1993)