Palaeoenvironments of Early Devonian fish and other aquatic fauna of the Campbellton Formation, New Brunswick, Canada

The palaeoecology and palaeoenvironments of the classic fish-bearing strata of the Campbellton Formation are here described. A well-documented fossil assemblage includes acanthodian, placoderm, chondrichthyan, and cephalaspid fishes, tracheophyte remains, eurypterids, ostracods, and molluscs. As part of the Old Red Sandstone continent, the Emsian Campbellton Formation occupied a small basin within the mountainous terrain of the Acadian Orogen, and may have connected through a narrow seaway to a closing foreland basin. The highest diversity of vertebrate fossils was found above a basal unconformity with Val dʹAmour Formation volcanics, marked by fissure-fills and unstratified breccia representing a craggy, irregular palaeosurface that provided shelter for some fauna and sediment for rapid burial of skeletal remains. Overlying prodeltaic calcareous siltstones are also highly fossiliferous, and represent a low energy habitat. Occurrences of pterygotid eurypterids, cephalaspids, and chondrichthyans in deltaic sandstones, place these taxa in a habitat that may have been variably fresh or brackish. The surrounding landscape was vegetated with primitive tracheophytes, and abundant plant debris is preserved throughout the basin. The diverse assemblage of fish, arthropods, gastropods, plants and microbial growths suggests that a trophically complex ecosystem was in existence.