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Microconchids have been described from the classic Pennsylvanian locality at Joggins, Nova Scotia. These encrusting tentaculitoid tubeworms have previously been mentioned and described from Joggins under the polychaete genus Spirorbis. Detailed morphological and microstructural investigation revealed that they belong to the species Microconchus carbonarius Murchison, confirming the previous tentative assignment (as Spirorbis carbonarius) made by Sir J. William Dawson in the nineteenth century. The occurrence of the same species in Upper Carboniferous deposits of England provides evidence supporting a connection between England and Nova Scotia in the Late Carboniferous (Pennsylvanian). Migration of the species could have been possible via brackish seas connecting both areas during maximum sea level during the Pennsylvanian. The species inhabited retrograding poorly drained coastal plain and open-water brackish environments, encrusting bivalve shells and plant remains in both sandstone and limestone deposits. Their high density (up to 19 individuals/cm2) may have resulted from their aggregative behaviour, high fecundity, and a lack of any competition with other skeleton-bearing encrusters. The large number (34%) of regenerated tubes indicates that microconchids were often preyed upon by associated animals, most probably fishes, which could graze on their dense encrusting aggregations. Des microconchides sont decrits qui proviennent de la localite pennsylvanienne classique de Joggins (Nouvelle- Ecosse). Ces vers a tube tentaculitoides incrustants ont deja ete mentionnes pour cette localite et decrits comme appartenant au genre des polychetes Spirorbis. Une etude morphologique et microstructurale detaillee a revele qu'ils appartiennent a l'espece Microconchus carbonarius Murchison, ce qui confirme leur affectation preliminaire anterieure (a Spirorbis carbonarius) par Sir J. William Dawson, au 19e siecle. La presence de la meme espece dans des depots du Carbonifere superieur d'Angleterre appuie l'existence d'un lien entre l'Angleterre et la Nouvelle-Ecosse au Carbonifere tardif (Pennsylvanien). La migration de l'espece pourrait avoir ete possible par l'intermediaire de mers saumatres reliant les deux regions, en periode de niveau maximum de la mer au Pennsylvanien. L'espece habitait des milieux de plaine cotiere mal drainee en retrogradation et d'eaux saumatres libres, des coquilles de bivalves et des restes de plantes s'incrustant dans des depots de gres et de calcaire. Leur densite elevee (jusqu'a 19 individus au [cm.sup.2]) pourrait etre le fait de leur comportement gregaire, leur grande fecondite et l'absence de toute concurrence avec d'autres especes incrustantes a squelette. Le grand nombre (34 %) de tubes regeneres indique que les microconchides etaient souvent la proie d'animaux associes, fort probablement des poissons, qui pouvaient brouter leurs denses agregations incrustantes. [Traduit par la Redaction], Introduction The Joggins Fossil Cliffs UNESCO World Heritage Site in Nova Scotia, Canada (Fig. 1), is one of the thickest successions of a Carboniferous coal basin in the world (Boon [...]

Coprolites offer insights into the diets of the animals that produced them, and thereby also provide a unique perspective of the paleoenvironments and paleoecosystems that existed during their deposition. Late [...]