Ichnocoenoses from the Carboniferous of eastern Canada and their implications for the recognition of ichnofacies in nonmarine strata

Abstract

Sixty-six suites of trace fossils from thirty-four different localities were collected or observed in the Carboniferous Mabou and Cumberland groups of western Cape Breton Island. Recurrent suites have been compiled into thirteen ichnocoenoses. Twelve of these ichnocoenoses, together with others from the Carboniferous elsewhere in the Maritimes, can be considered representative of two revised ichnofacies and their related composite ichnofacies. The remaining ichnocoenosis is currently anomalous. In our view, some ichnofacies identifi ed in the nonmarine realm have been too broadly defi ned. They allow for the inclusion of ichnocoenoses that are better considered representatives of composite ichnofacies. The Mermia ichnofacies is thus emended to consist primarily of systematic-coverage interface burrows and trails, irregular interface burrows and trails, non-striate pits, sinusoidal burrows and trails, migrating burrows, systematic-coverage burrow networks, (dense coverage) simple burrows and, if present, subordinate trackways. It remains an ichnofacies indicative of quiet water, oxygenated, permanently subaqueous conditions with signifi cant organic input. Two Cape Breton Island ichnocoenoses are representative of the revised Mermia ichnofacies. The Scoyenia ichnofacies is emended to consist primarily of bilobate or striate pits and trails, trackways, meniscate burrows, (sparse coverage) simple burrows and, if present, subordinate vertical burrows. It remains an ichnofacies indicative of transitional environments, specifi cally quiet water conditions that regularly dry out, or periodically inundated fl oodplains. Four Cape Breton Island ichnocoenoses are representative of the revised Scoyenia ichnofacies. Six ichnocoenoses from Cape Breton Island contain some trace fossils considered typical of both the Mermia and Scoyenia ichnofacies as emended. Two interpretations are possible. These ichnocoenoses might indicate instances where the trace-fossil producers were environmentally tolerant animals that could inhabit and behave similarly in either setting. Alternatively, they may represent cases where producers active in different environments had their traces juxtaposed or even overprinted due to a change in environmental conditions. In this latter case, the ichnocoenoses can be considered examples of composite ichnofacies that are taphonomic successors of combinations of the Mermia, Scoyenia, and the well-established Skolithos ichnofacies. RÉSUMÉ Soixante-six ensembles d'ichnofossiles de 34 emplacements différents ont été prélevés ou observés dans les groupes carbonifères de Mabou et de Cumberland dans l'ouest de l'île du Cap-Breton. Les ensembles répétitifs ont été compilés au sein de 13 ichnocoenoses. Douze de ces ichnocoenoses, auxquelles on peut ajouter les autres exemplaires du Carbonifère présents ailleurs dans les Maritimes, peuvent être considérées comme des types représentatifs de deux ichnofaciès révisés et de leurs ichnofaciès composites connexes. Les autres ichnocoenoses constituent actuellement des types...

Insights into an Early Jurassic dinosaur habitat: ichnofacies and enigmatic structures from the Portland Formation, Hoover Quarry, Massachusetts, U.S.A.

“…In continental rocks from the Cretaceous of South Korea, Kim et al (2005) also concluded that in some of their track bearing ichnocoenoses there were traces characteristic of the Mermia, Skolithos, and Scoyenia ichnofacies. These authors separated traces into "morphological groups" that themselves are characteristic of discrete ichnofacies, and used these groups to conclude that some of their assemblages represented composites of more than one ichnofacies (Keighley and Pickerill 2003;Kim et al 2005). If the approach of these authors is applied to the Hoover Quarry assemblage, morphological groups VII (Palaeophycus, Planolites), VIII (Eubrontes cf.…”

“…However, in continental settings, most workers report Planolites in lacustrine, floodplain, or channel facies; thus, standing water (or at least fully saturated substrates) seems to be a necessity for the Planolites tracemaker (Gierlowski-Kordesch 1991; Pickerill 1992; Buatois and Mangano 1993;MacNaughton and Pickerill 1995;Metz 1996;Keighley and Pickerill 2003;Gillette et al 2003;Melchor 2004). The Planolites producer may be a variety of vermiform animals, perhaps polychaetes (Pemberton and Frey 1982), although arthropods, including insect larvae, are more likely producers in continental settings (Buatois and Mangano 1993).…”

“…Although only two specimens confidently attributable to Scoyenia were recovered from the Hoover Quarry, the overall assemblage of this site is assigned to a Scoyenia-Skolithos composite ichnofacies based on criteria outlined by , Buatois and Mangano (1995), and Keighley and Pickerill (2003). Currently, the Scoyenia ichnofacies is considered representative of moist or wet fine-grained sediments in shallow, low energy, aquatic deposits that are either periodically exposed to air, or are in low areas periodically inundated by water Buatois and Mangano 1995).…”

“…Keighley and Pickerill (2003) offered emended concepts for the Mermia and Skolithos ichnofacies, and in Carboniferous nonmarine rocks of eastern Canada, recognized ichnocoenoses that contained traces from both ichnofacies. In continental rocks from the Cretaceous of South Korea, Kim et al (2005) also concluded that in some of their track bearing ichnocoenoses there were traces characteristic of the Mermia, Skolithos, and Scoyenia ichnofacies.…”

“…In this contribution we examine a suite of non-marine strata comparable to that of Gierlowski-Kordesch's studies and exposed in the Hoover Sandstone Quarry in East Longmeadow, Massachusetts, in order to characterize the paleoecology of the fauna and to augment our understanding of Scoyenia and related continental ichnofacies (sensu Smith et al 1993;Keighley and Pickerill 2003;Lawfield and Pickerill 2006). In addition to describing the invertebrate traces, we examine vertebrate tracks and previously recovered vertebrate skeletal material from the Hoover Quarry, and integrate this paleontological data with limited sedimentologic and regional stratigraphic information to help place the Hoover Quarry trace association within known ichnofacies.…”