Rey) with vestiges of sauropod tracks; south of James Price Point. B, a similar but smaller feature at James Price Point, at the very margin of the lower-lying areas shown in Figure 24. The two water-filled areas at left and right have been trodden down by sauropods to leave an `anticlinal’ fold between them. doi:10.1371/journal.pone.0036208.gtransmitted reliefs of an entire trackway. In theory the same concession might extend ultimately to regions of deformed bedding that resemble minor tectonic structures and even to the larger features of physical geography seen at James Price Point. In effect, the state of ichnotaxonomy would come to resemble that of zoological taxonomy when the available names of taxa were extended to the `work’ of animals [47]. Seemingly valid ichnotaxonomic names might be bestowed on geographic features of the Dampier coast, in just the way that the name Homo sapiens might be applied to all and any human artefacts, from stone axes to space shuttles. It seems preferable to avoid that incongruous outcome by maintaining the genuine, if arbitrary, distinction between footprints and sedimentary structures (patterns of deformation) which are associated with footprints. That policy is, in fact, consistent with conventional practice in ichnotaxonomy, where features of transmitted relief are disregarded or treated, at best, as an indirect and inferior source of information about the `true’ footprints. Footprints, sensu stricto, are definitely objects of organic origin whereas the development of transmitted reliefs depends as much on the nature of the substrate as it does on the intervention of a track-maker. In fact, the development of transmitted relief, in the broadest sense, does not necessarily require the active involvement of a track-maker. In theory transmitted reliefs might be produced by organisms which are inert (e.g. a carcass T0901317MedChemExpress T0901317 settlingon to the floor of a lagoon) or by the impact of inorganic objects such as drop-stones, lapilli, volcanic bombs, meteorites or hail. Even so, the taxonomic implications should not be overrated. Ideally ichnotaxa should be established on type material comprising one or more footprints (true tracks), not transmitted reliefs (undertracks). But that is merely the description of ideal practice; it is not the stipulation of a mandatory requirement. Each case is to be judged on its individual merits, and no great harm will ensue if a valid ichnospecies should transpire to be founded on transmitted relief rather than a footprint (a true track). In practice all that matters is that type material should be adequate and diagnostic, regardless of its status as footprint or transmitted relief. That concession is not the thin end of a wedge that would ultimately permit all and any transmitted reliefs to be classified as conventional ichnotaxa, because only the most proximal reliefs are likely to retain the morphological details required to discriminate a valid ichnospecies. The more order I-CBP112 distal transmitted reliefs lack such consistent morphological detail and are far less likely to be mistaken for footprints (true tracks) – though they might easily and more appropriately be classified as a series of sedimentary structures (e.g. bowls, basins, troughs and folds of various shapes and sizes).Previous interpretationsSome of the sedimentary features described here may have attracted attention in the past, though the sauropod tracks werePLoS ONE | www.plosone.orgSubstrates Deformed by Cretaceous Dinosaurs.Rey) with vestiges of sauropod tracks; south of James Price Point. B, a similar but smaller feature at James Price Point, at the very margin of the lower-lying areas shown in Figure 24. The two water-filled areas at left and right have been trodden down by sauropods to leave an `anticlinal’ fold between them. doi:10.1371/journal.pone.0036208.gtransmitted reliefs of an entire trackway. In theory the same concession might extend ultimately to regions of deformed bedding that resemble minor tectonic structures and even to the larger features of physical geography seen at James Price Point. In effect, the state of ichnotaxonomy would come to resemble that of zoological taxonomy when the available names of taxa were extended to the `work’ of animals [47]. Seemingly valid ichnotaxonomic names might be bestowed on geographic features of the Dampier coast, in just the way that the name Homo sapiens might be applied to all and any human artefacts, from stone axes to space shuttles. It seems preferable to avoid that incongruous outcome by maintaining the genuine, if arbitrary, distinction between footprints and sedimentary structures (patterns of deformation) which are associated with footprints. That policy is, in fact, consistent with conventional practice in ichnotaxonomy, where features of transmitted relief are disregarded or treated, at best, as an indirect and inferior source of information about the `true’ footprints. Footprints, sensu stricto, are definitely objects of organic origin whereas the development of transmitted reliefs depends as much on the nature of the substrate as it does on the intervention of a track-maker. In fact, the development of transmitted relief, in the broadest sense, does not necessarily require the active involvement of a track-maker. In theory transmitted reliefs might be produced by organisms which are inert (e.g. a carcass settlingon to the floor of a lagoon) or by the impact of inorganic objects such as drop-stones, lapilli, volcanic bombs, meteorites or hail. Even so, the taxonomic implications should not be overrated. Ideally ichnotaxa should be established on type material comprising one or more footprints (true tracks), not transmitted reliefs (undertracks). But that is merely the description of ideal practice; it is not the stipulation of a mandatory requirement. Each case is to be judged on its individual merits, and no great harm will ensue if a valid ichnospecies should transpire to be founded on transmitted relief rather than a footprint (a true track). In practice all that matters is that type material should be adequate and diagnostic, regardless of its status as footprint or transmitted relief. That concession is not the thin end of a wedge that would ultimately permit all and any transmitted reliefs to be classified as conventional ichnotaxa, because only the most proximal reliefs are likely to retain the morphological details required to discriminate a valid ichnospecies. The more distal transmitted reliefs lack such consistent morphological detail and are far less likely to be mistaken for footprints (true tracks) – though they might easily and more appropriately be classified as a series of sedimentary structures (e.g. bowls, basins, troughs and folds of various shapes and sizes).Previous interpretationsSome of the sedimentary features described here may have attracted attention in the past, though the sauropod tracks werePLoS ONE | www.plosone.orgSubstrates Deformed by Cretaceous Dinosaurs.
