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The Early Mississippian (known as 'Romer's Gap') marks the beginning of a critical point in tetrapod history as they transitioned from dominantly aquatic to more terrestrial ecosystems. This paleoecological expansion set the stage for the radiation of all terrestrial tetrapod crown groups. The exact timing for the transition into freshwater continental environments is poorly understood. However, new discoveries in Scotland, England, and Nova Scotia, represent rare exceptions; offering a glimpse into coastal terrestrial ecologies during 'Romer's Gap'. These sites have evidence for a marine-water connection suggesting a coastal paleogeographic position. In contrast, Early Mississippian sedimentary deposits of the Moncton Subbasin in southern New Brunswick (NB) are interpreted as freshwater intra-continental conditions (lacustrine, wetland, fluvial, alluvial settings). A single stratigraphic horizon in the Albert Formation (Hiram Brook Member), exposed near Norton, NB, has yielded abundant tetrapod footprints. Preliminary assessments suggest at least four trackway ichnogenera: cf. Characichnos, cf.Matthewichnus, cf.Hylopus, and cf.Batrachichnus and a fifth trackway that may represent a new ichnogenus. Footprints range in size from 1 to 3 cm, suggesting that tetrapods were smaller than those documented from near time-equivalent sites in Nova Scotia, but are comparable in size to skeletal fossils described from younger strata in Scotland. These footprints are interpreted to be preserved in interfluvial crevasse splays associated with wetland forests dominated by Lepidodendropsis lycopods and Aneimites ferns preserved in their ecological context. The relatively large sample size of footprints suggests that a community of tetrapods were present and part of a diverse ecosystem, adapted to terrestrial and semi-aquatic continental environments in the earliest Mississippian. Additional trackways from slightly younger redbed playa lake deposits in the Sussex Group suggest tetrapods were also venturing into semi-arid continental environments. The ichnofossil assemblage from NB demonstrates considerable variation in ichnotaxa morphology and paleoenvironmental context from sites of approximately equivalent age. [ABSTRACT FROM AUTHOR]

The Fundy Basin of Nova Scotia and New Brunswick, Canada, is the most northern extent of the Triassic-Jurassic Newark Supergroup on land. Mesozoic sedimentary rocks in New Brunswick are rare by comparison to the neighbouring province of Nova Scotia. The Upper Triassic is known for the oldest dinosaurs in Canada, together with other vertebrates, invertebrates, plants, and ichnofossils from the Upper Triassic of the Wolfville and Blomidon formations. The present study has found the first evidence of vertebrate life from the Triassic of New Brunswick in the Alma area the Bay of Fundy. A single horizon from strata at Waterside Beach has yielded isolated vertebrate bones (vertebral element, limb bone, isolated tooth and bone fragments), while at a second outcrop along Dennis Beach, a single horizon of mudstone preserved vertebrate ichnofossils. UAV-based photographs have been collected to digitally preserve 3D models of the outcrops. This documents the current context, as these coastal sites experience tidal erosion, exposing new outcrop. The ichnoassemblage includes footprints of dinosauromorphs (e.g., lagosuchians; ichnotaxon: Rotodactylus), lepidosauromorphs/archosauromorphs (ichnotaxon: Rhynchosauroides), Archosauriformes and "Rauisuchia" (ichnotaxon: Synaptichnium), and an unidentified dinosaur-like track. Rotodactylus is thought to represent dinosauromorphs that are close to the beginning of the dinosaurian clade and is an index ichnogenus with a limited stratigraphic range of Early Triassic (latest Olenekian) through the Middle Triassic (Anisian to the earliest Ladinian). The elements of the fossil assemblage described here are commonly found together and comparable to other sites of similar Early-Middle Triassic age in Morocco, South America, and Poland. This restricts the age of the Triassic strata at Dennis Beach and the vertebrate footprints preserved at that locality to between the latest Lower Triassic and the Middle Triassic, making it the oldest evidence of vertebrates from the Mesozoic in Canada inferred from footprints and isolated bones. [ABSTRACT FROM AUTHOR]