A new species of the phlyctaeniid arthrodire genus Groenlandaspis from the upper Famennian of Belgium is described. The remains of Groenlandaspis potyi sp. nov. consist of dissociated thoracic armor elements, but the specimen designed to be the holotype displays the median dorsal, anterior and posterior dorsolateral plates in connection. Though incomplete, the new species is characterized by an equilateral triangle-shaped median dorsal plate, a protruding posterodorsal apron of the posterior dorsolateral plate behind the overlap area for the median dorsal plate, and an overall lack of ornamentation. Groenlandaspis potyi sp. nov. constitutes the second occurrence of a Groenlandaspis species in continental Europe after the description of Groenlandaspis thorezi from upper Famennian quarries of Belgium. Another probable new species of Groenlandaspis is also described, though of unknown locality and horizon; it can however be deduced from the upper Famennian of Belgium without more precision. Together with some unpublished material of groenlandaspidids from the Famennian tetrapod-bearing locality of Strud, this material highlights the richness of the Groenlandaspididae diversity in Belgium. The discovery of Groenlandaspis potyi sp. nov. in Belgium reinforces the Famennian global distribution of this widespread genus during this period. Also, since those organisms have possibly been considered as non;marine indicators, this material is another argument pleading for close relationships between Euramerica and Gondwana around the Frasnian-Famennian boundary.
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Abstract Caecilians are elongate, limbless and annulated amphibians that, as far as is known, all have an at least partly fossorial lifestyle. It has been suggested that elongate limbless vertebrates show little morphological differentiation throughout the postcranial skeleton. However, relatively few studies have explored the axial skeleton in limbless tetrapods. In this study, we used ?CT data and three-dimensional geometric morphometrics to explore regional differences in vertebral shape across a broad range of caecilian species. Our results highlight substantial differences in vertebral shape along the axial skeleton, with anterior vertebrae being short and bulky, whereas posterior vertebrae are more elongated. This study shows that despite being limbless, elongate tetrapods such as caecilians still show regional heterogeneity in the shape of individual vertebrae along the vertebral column. Further studies are needed, however, to understand the possible causes and functional consequences of the observed variation in vertebral shape in caecilians.
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RBINS Staff Publications 2022
