Matt Stimson

The end-Permian extinction was the largest such event in earth history and resulted in the ecologic restructuring of both terrestrial and marine environments. The dynamics and timing of marine ecologic recovery following this event has been the subject of numerous studies incorporating body and trace fossils. We report a relatively low diversity ichnoassemblage at a Utah Geological Survey fossil site (UGS locality 42Ws643T) in the upper Timpoweap Member (Smithian) of the Moenkopi Formation. The ichnoassemblage consists of predominantly horizontal locomotion and feeding traces typical of the Cruziana ichnofacies. Most of the traces are preserved in concave or convex epirelief and come from an approximately meter-thick package of coarsening upward, fine-grained, silty limestone bounded above and below by coarser-grained limestones. The trace fossil horizon is interpreted as a shallow, marine lagoon or shelf environment below fair weather wave base. Traces presumably produced by arthropods are dominant (Kouphichnium lithographicum, Protichnites, Petalichnus, and Cruziana) with rare occurrences of other invertebrate (Helminthoidichnites and Thalassinoides) and vertebrate (Undichna) traces. Occurrences of Petalichnus may actually be deep lateral impressions of Kouphichnium. Many of the trace fossil surfaces also preserve wrinkle structures, suggesting the presence of microbially stabilized substrates that may have played a role in increasing the preservation potential of the traces. The prevalence of microbial mats and the exceptional preservation of these traces are most likely due to greatly reduced infaunal bioturbation as a result of delayed ecologic recovery after the end-Permian mass extinction. This resulted in a loss of the sedimentary mixed layer providing a taphonomic window for detailed preservation similar to that observed in Early Cambrian and Lower Triassic deposits, including elsewhere in the Moenkopi. The ichnoassemblage preserved at UGS 42Ws643T also provides additional information concerning the diversity of shallow water environments during the Early Triassic and has implications for interpreting the global timing of ecologic recovery following the end-Permian mass extinction.

The Joggins Fossil Cliffs were inscribed as a UNESCO World Heritage Site in July 2008 and represent the world's finest example of a Coal Age ecosystem. This 15 km-long coastal cliff section displays multiple horizons of fossilized Carboniferous (310–325 Ma) forests. The Joggins fossil cliffs have yielded more than 200 different species of plants and animals, including the fossil record's earliest known amniote (Hylonomous lyelli) and the earliest land snail (Dendropupa vetusa),which are found entombed within the erect fossil lycopsid trees. Body fossils of terrestrial biota are not the only evidence of life preserved in Joggins; a diverse trace fossil assemblage of trackways from both vertebrate and invertebrate life is also found at this site. The trace fossil record at Joggins is as impressive as the creatures themselves and adds an important piece to the puzzle of life during the Coal Age. Although sometimes regarded as less important than body fossils, trace fossils provide important information about the locomotion and behaviour of prehistoric fauna and in some cases are the only evidence of a creature's existence. The existence of horseshoe crab activity within the Joggins Formation is well known; however, it remains a poorly studied part of the Coal Age ecosystem. We present here an overview of the paleoichnology of Carboniferous limulids from the Joggins Fossil Cliffs and their paleoenviromental implications of a possible coastal connection. Unquestionable undertracks of these limulids have been discovered, examined, and identified as the morphological equivalent to small-scale specimens of the ichnogenus Diplichnites. The ichnogenus Diplichnites is currently assigned to myriapods, including the colossal two metre long, half metre wide Arthropleura. The similarity between the two ichnofossils poses problems for the taxonomy of an already confusing ichnotaxa. On the other hand, it also explains the close proximity of both Koupichnium (limulid) and small-scale Diplichnites (myriapod) trackways within the same paleoenvironment, which is an unlikely association. This issue is reviewed and possible solutions proposed.

The classic Carboniferous section at Joggins is most famous for the discovery of standing fossil lycopsid trees that bear a terrestrial fauna within their once hollowed out stumps. The first discovery of this diverse entombed fauna was made by Sir John William Dawson and Sir Charles Lyell in 1852. Dawson’s extensive explorations of a single fossil forest at Coal Mine Point continued throughout the latter half of the nineteenth century. Eighteen productive trees were documented which yielded 12 species of tetrapods and 6 species of terrestrial arthropods. Among the disarticulated skeletal remains was the world’s oldest known reptile (oldest amniote) named Hylonomous lyelli. Only two other tetrapod-bearing trees have been discovered between Dawson’s death in 1899 until recent work (1994-present). Walter Bell noted two tetrapod-bearing stumps during the early twentieth century, however, the stratigraphic horizons and the specimens’ whereabouts remain unknown. The development of a search strategy informed by Dawson’s writings, and study of his specimens in London and Montreal, has resulted in the discovery of eight additional tetrapodbearing trees from six new stratigraphic horizons other than Dawson’s Coal Mine Point fossil forest since 1994. Most of the fossiliferous trees discovered in recent years conform to the general model described by Dawson, with tetrapods occurring near the basal mineral charcoal infill which records evidence of wildfires. Three of these productive trees derive from a sequence of upright lycopsids underlying the Forty Brine coal seam. The Forty Brine tetrapod-bearing trees demonstrate persistence of ecological conditions in successive lycopsid forests, wherein entire forest stands were charred by repeated wildfire disturbance, and in at least one case, resulting in the formation of an unequivocal basal fire scar. These, in addition to the other five tetrapod-bearing forests, confirm that Dawson and Lyell’s forest was not unique or unusual but that similar paleoecological conditions recurred. It is also unlikely that these conditions were exclusive to Joggins, and as yet undiscovered tetrapodbearing forests doubtless occurred in wetlands of the tropical biome where seasonality promoted disturbance and wildfire. Experimental computed tomography (CT) scanning shows promise in revealing the distribution of bone material within the tree fills, most of which is concentrated in the basal 15 cm in association with charred plant material. Tetrapod bones from the trees are presently being analyzed by electron microprobe to determine whether their CaO/P2O5 ratios record details of their thermal history and consequently about the chronology of their entombment as it relates to wildfire events and tree burial. The ability to study the taphonomy of the tree hollow fauna also permits evaluation of various scenarios of their entombment, in particular the long held pitfall theory and the newer perception of a hollow tree guild (denning). Our recent discoveries not only provide a clearer understanding of the role of wildfires in the development of the ecological niche inhabited by the earliest amniotes, but also unveil a rich new source of tetrapod skeletal material from this pivotal moment in vertebrate evolution.

Vertebrate ichnotaxa described by George Frederic Matthew in 1910 from the Upper Carboniferous (Lower Pennsylvanian) ‘Fern Ledges’ of Saint John, New Brunswick, were dismissed as dubious trackways by previous authors. Thus, three new ichnospecies Matthew described appeared in the 1975 Treatise on Invertebrate Paleontology as “unrecognized or unrecognizable” and were mostly forgotten by vertebrate ichnologists. These traces include Hylopus (?) variabilis, Nanopus (?) vetustus and Bipezia bilobata. One ichnospecies, Hylopus (?) variabilis, here is retained as a valid tetrapod footprint ichnotaxon and reassigned to the ichnogenus Limnopus as a new combination, together with other poorly preserved specimens Matthew labeled, but never described. Nanopus (?) vetustus and Bipezia bilobata named by Matthew in the same paper, have been reexamined and remain as nomina dubia. 

Red-bed strata exposed at Lepreau Falls, southern New Brunswick, were originally interpreted as belonging to the Triassic Lepreau Formation. Poorly preserved tetrapod trackways within the strata were previously assigned to two ichnospecies; one to a new Triassic ichnospecies, Isocampe lepreauense Sarjeant and Stringer, and the other to Rhynchosauroides cf. R. franconicus (Heller). Both were attributed to reptiles. Subsequent mapping of the rocks and reassignment of the exposed strata at Lepreau Falls to the Mississippian Mabou Group prompted our re-examination of the trackway fossils. Isocampe lepreauense was described from a specimen block preserving three trackways and the original description was based on erroneous interpretation of extramorphological digit drags. Rhynchosauroides cf. R. franconicus was a tentative assignment in a letter accompanying a cast in the New Brunswick Museum, but was never formally published. We redescribe and re-interpret all the trackways as gait vari...

A stem-relative of dragon- and damselflies, Brunellopteron norradi Béthoux, Deregnaucourt and Norrad gen. et spec. nov., is documented based on a specimen found at Robertson Point (Grand Lake, New Brunswick, Canada; Sunburry Creek Formation; early Moscovian, Pennsylvanian) and preserving the basal half of a hindwing. A comparative analysis of the evolution of wing venation in early odonates demonstrates that it belongs to a yet poorly documented subset of species. Specifically, it displays a MP+CuA fusion, a CuA+CuP fusion, and a CuP+AA fusion, but lacks the 'extended' MP+Cu/CuA fusion and the 'extended' (CuP/CuA+CuP)+AA fusion which occurrence is typical of most Odonata, including Meganeura-like species. The occurrence of intercalary veins suggests that its closest relative might be Gallotypus oudardi Nel, Garrouste and Roques, 2008, from the Moscovian of northern France.

The Joggins Fossil Cliffs were inscribed as a UNESCO World Heritage Site in July 2008 and represent the world's finest example of a Coal Age ecosystem. This 15 km-long coastal cliff section displays multiple horizons of fossilized Carboniferous (310–325 Ma) forests. The Joggins fossil cliffs have yielded more than 200 different species of plants and animals, including the fossil record's earliest known amniote (Hylonomous lyelli) and the earliest land snail (Dendropupa vetusa),which are found entombed within the erect fossil lycopsid trees. Body fossils of terrestrial biota are not the only evidence of life preserved in Joggins; a diverse trace fossil assemblage of trackways from both vertebrate and invertebrate life is also found at this site. The trace fossil record at Joggins is as impressive as the creatures themselves and adds an important piece to the puzzle of life during the Coal Age. Although sometimes regarded as less important than body fossils, trace fossils prov...

The classic Carboniferous section at Joggins is most famous for the discovery of standing fossil lycopsid trees that bear a terrestrial fauna within their once hollowed out stumps. The first discovery of this diverse entombed fauna was made by Sir John William Dawson and Sir Charles Lyell in 1852. Dawson’s extensive explorations of a single fossil forest at Coal Mine Point continued throughout the latter half of the nineteenth century. Eighteen productive trees were documented which yielded 12 species of tetrapods and 6 species of terrestrial arthropods. Among the disarticulated skeletal remains was the world’s oldest known reptile (oldest amniote) named Hylonomous lyelli. Only two other tetrapod-bearing trees have been discovered between Dawson’s death in 1899 until recent work (1994-present). Walter Bell noted two tetrapod-bearing stumps during the early twentieth century, however, the stratigraphic horizons and the specimens’ whereabouts remain unknown. The development of a searc...

The end-Permian extinction was the largest such event in earth history and resulted in the ecologic restructuring of both terrestrial and marine environments. The dynamics and timing of marine ecologic recovery following this event has been the subject of numerous studies incorporating body and trace fossils. We report a relatively low diversity ichnoassemblage at a Utah Geological Survey fossil site (UGS locality 42Ws643T) in the upper Timpoweap Member (Smithian) of the Moenkopi Formation. The ichnoassemblage consists of predominantly horizontal locomotion and feeding traces typical of the Cruziana ichnofacies. Most of the traces are preserved in concave or convex epirelief and come from an approximately meter-thick package of coarsening upward, fine-grained, silty limestone bounded above and below by coarser-grained limestones. The trace fossil horizon is interpreted as a shallow, marine lagoon or shelf environment below fair weather wave base. Traces presumably produced by arthropods are dominant (Kouphichnium lithographicum, Protichnites, Petalichnus, and Cruziana) with rare occurrences of other invertebrate (Helminthoidichnites and Thalassinoides) and vertebrate (Undichna) traces. Occurrences of Petalichnus may actually be deep lateral impressions of Kouphichnium. Many of the trace fossil surfaces also preserve wrinkle structures, suggesting the presence of microbially stabilized substrates that may have played a role in increasing the preservation potential of the traces. The prevalence of microbial mats and the exceptional preservation of these traces are most likely due to greatly reduced infaunal bioturbation as a result of delayed ecologic recovery after the end-Permian mass extinction. This resulted in a loss of the sedimentary mixed layer providing a taphonomic window for detailed preservation similar to that observed in Early Cambrian and Lower Triassic deposits, including elsewhere in the Moenkopi. The ichnoassemblage preserved at UGS 42Ws643T also provides additional information concerning the diversity of shallow water environments during the Early Triassic and has implications for interpreting the global timing of ecologic recovery following the end-Permian mass extinction.

1st Joggins Research Symposium Joggins, Nova Scotia The first Joggins Research Symposium was held at the Joggins Fossil Centre, Joggins, Nova Scotia, on 22 September, 2018. The Symposium was part of the celebration of the 10th anniversary of the designation of Joggins Fossil Cliffs as a UNESCO World Heritage Site. Its purpose was to highlight recent and current research at the site. The Joggins Fossil Institute staff and Science Advisory Committee facilitated a fruitful meeting, with 12 submitted abstracts and over 25 participants, including academic and government scientists and representatives from the Nova Scotia Museum and the Fundy Geological Museum. Not surprisingly, the conference also included a field trip to the Joggins Fossil Cliffs beach where there was plenty of time for discussion and inspiration. In the following pages, we are pleased to provide the abstracts of oral presentations from the meeting. As you will see, topics included ichnology, sedimentology, education an...

The Campbellton Formation has long been known to yield a fossil assemblage of Devonian (Emsian) fish and eurypterids at its westernmost exposure near Campbellton and Atholville, and a well described flora and early land animal fauna toward its easternmost exposure near Dalhousie Junction. Although the body fossil assemblage (paleobotany, vertebrate and invertebrate paleontology), paleoecology and paleoenvironmental context of the formation have been extensively studied, ichnofossils are rare and have not been described previously. Fossils from the vertebrate and eurypterid bearing ‘Atholville Beds’ contain a low diversity ichnofossil assemblage represented by three ichnotaxa:Monomorphichnus, ?Taenidium and Helminthoidichnites. Monomorphichnus is proposed here as being produced by the produced by the activity of the eurypterid Pterygotus anglicus.

A new specimen of Batrachichnus salamandroides from the classic Carboniferous section at Joggins, Nova Scotia, is the smallest set of tetrapod footprints known in the fossil record. The trackmaker was a juvenile, quadrupedal temnospondyl or microsaur with a trunk length of 3.55 mm and an estimated body length of 8 mm (skull, presacral vertebrae, and caudal vertebrae). The 48 mm-long trackway preserves a high degree of extramorphological variation along its course, including a gait change associated with a change in direction along with an increased stride and pace, and the appearance of overstepped imprints, in the latter portion of the trackway. These morphological changes suggest the tetrapod changed from a walking gait to a running gait.