title: Ichnotaxonomic review of large ornithopod dinosaur tracks: temporal and geographic implications.
abstract: BACKGROUND
  Large ornithopod tracks are known from the Upper Jurassic to the uppermost Cretaceous rocks of all continents but Antarctica. They include the tracks historically called Iguanodon footprints, iguanodontid footprints, hadrosaur/hadrosaurid footprints, and other large ornithopod tracks that have been used to define ichnotaxa. More than 40 ichnospecies based on large ornithopod tracks have been defined, but the validity of many of them is questionable.
  
  
  RESULTS
  34 ichnogenera and 44 ichnospecies have been analysed in this work. Many of them are considered to be invalid because they have been defined on the basis of poorly preserved tracks without diagnostic features, have an inadequate diagnosis, or are based on temporal and/or geographical criteria. Only eight ichnospecies belonging to the ichnogenera Caririchnium, Iguanodontipus and Hadrosauropodus are here regarded as valid.
  
  
  CONCLUSIONS
  The monospecific ichnogenus Iguanodontipus (I. burreyi) is characterized by a small, rounded heel and elongate, narrow digit impressions. Its distribution is limited to the Berriasian-Valanginian of Europe. Caririchnium consists of four ichnospecies (C. magnificum [type ichnospecies], C. kortmeyeri, C. billsarjeanti and C. lotus) with a large, rounded heel and short, wide digit impressions. This ichnogenus ranges from the Berriasian-Hauterivian to the Aptian-Albian of South America, North America, Asia and Europe. Finally, Hadrosauropodus (three ichnospecies: H. langstoni [type ichnospecies], H. leonardii and H. kyoungsookimi) shows a large, bilobed heel and short, wide digit impressions. It is known from the Aptian-Albian to the Maastrichtian of North America, Asia and Europe. The ichnofamily Iguanodontipodidae includes large iguanodontian tracks characterized mainly by mesaxonic, tridactyl and subsymmetrical pes tracks that are as wide as (or wider than) long and have one pad impression in each digit and one in the heel. Its distribution is confidently limited to the Cretaceous of Europe, Asia, North America and South America.
authors: CONICET-Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, General Roca 1242, 8332 Fisque Menuco (General Roca), Río Negro, Argentina; Facultad de Ciencas, Estudios Agroalimentarios e Informática, Universidad de La Rioja, Madre de Dios 51-53, 26006 Logroño, La Rioja, Spain.
authors: Ignacio
authors: I
authors: Díaz-Martínez
authors: Universidad del País Vasco/Euskal Herriko Unibertsitatea, Facultad de Ciencia y Tecnología, Departamento de Estratigrafía y Paleontología, Apartado 644, 48080, Bilbao, Spain.
authors: Xabier
authors: X
authors: Pereda-Suberbiola
authors: Facultad de Ciencas, Estudios Agroalimentarios e Informática, Universidad de La Rioja, Madre de Dios 51-53, 26006 Logroño, La Rioja, Spain.
authors: Félix
authors: F
authors: Pérez-Lorente
authors: Grupo Aragosaurus-IUCA, Área de Paleontología, Facultad de Ciencias, Universidad de Zaragoza, Pedro Cerbuna 12, 50009, Zaragoza, Spain.
authors: José Ignacio
authors: JI
authors: Canudo
mesh_terms: D000818:Animals; D025061:Dinosaurs; D005843:Geography; D010163:Paleontology; D062211:Spatio-Temporal Analysis