The Association of Anastomosed Fluvial Deposits and Dinosaur Tracks, Eggs, and Nests: Implications for the Interpretation of Floodplain Environments and a Possible Survival Strategy for Ornithopods

Facies architecture and palaeoenvironmental implications of the upper Cretaceous (Santonian) Csehbánya formation at the Iharkút vertebrate locality (Bakony Mountains, Northwestern Hungary)

“…These sandstone bodies are clearly isolated from each other, embedded in floodplain sediments suggesting multiple co-existing channels. The above mentioned characters are considered as diagnostic features of anastomosing river deposits (Eberth and Miall, 1991;Kirschbaum and McCabe, 1992;Nadon, 1993Nadon, , 1994Makaske, 2001;Horiuchi et al, 2012). The grain size range of Unit 2 varies from fine-to medium-grained sandstone and both the lower and the upper contacts of this unit are typically gradational.…”

“…One of the reasons for the accumulation of rich vertebrate fossil-bearing strata is that a relatively high number of animals are attracted to the floodplain due to abundant water and food supply (different plants or prey), which can result in a rich accumulation of bones (Behrensmeyer, 1988;Nadon, 1993;Andersson and Kaakinen, 2004). Furthermore, certain floodplain environments are favourable for bone preservation because of the relatively high depositional rate, post-mortem transportation, and reworking of animal remains by various fluvial processes (Behrensmeyer, 1988;Aslan and Behrensmeyer, 1996).…”

“…A significant part of continental vertebrate fossils is found in alluvial deposits thus the reconstruction of the depositional history of alluvial sequences is the main goal of any sedimentological, paleontological and taphonomical examination of vertebrate sites (Behrensmeyer, 1982(Behrensmeyer, , 1988Retallack, 1984; Badgley, 1986a,b;Eberth and Miall, 1991;Nadon, 1993;Therrien, 2005;Roberts, 2007). One of the reasons for the accumulation of rich vertebrate fossil-bearing strata is that a relatively high number of animals are attracted to the floodplain due to abundant water and food supply (different plants or prey), which can result in a rich accumulation of bones (Behrensmeyer, 1988;Nadon, 1993;Andersson and Kaakinen, 2004).…”

“…Splay deposits usually formed during periods of overbank flooding (Nadon, 1994;Makaske, 2001;Roberts, 2007) when the transport capacity of the flow was drastically reduced after leaving a channel causing most of the sediment load to be deposited on the floodplain (van Gelder et al, 1994). Such sheet deposits are commonly associated with ribbon sandstones of anastomosing river systems (Smith et al, 1989;Eberth and Miall, 1991;Kirschbaum and McCabe, 1992;Miall, 1996;Nadon, 1993;Makaske, 2001;Makaske et al, 2002;Roberts, 2007) and suggest that flooding events must have been characteristic features …”

“…Georgakakos, 1987;Malmon et al, 2004;Rogers, 2005;Billi, 2007). Anastomosing river systems often form in response to a strongly seasonal rainfall (Nadon, 1993(Nadon, , 1994. Furthermore, Nadon (1994) …”