This paper reports on an orphaned collection of echinoderms housed at the Durban Natural Science Museum, South Africa. The collection includes holotypes of the South African endemic ophiuroid Asteroschema capensis Mortensen, 1925 [=Asteromorpha capensis (Mortensen, 1925)] according to Okanishi et al. (2013) and the South African endemic asteroid Anthenoides marleyi Mortensen, 1925. The holotype of the asteroid Hacelia superba var. capensis Mortensen, 1925 has not been found and is considered lost, whilst the holotype of Anthosticte pacei Mortensen, 1925 [=Tethyaster pacei (Mortensen, 1925)] is reported to be housed in the Zoological Museum Copenhagen, Denmark. The collection includes both wet and dry specimens of extant Asteroidea, Ophiuroidea, Echinoidea and Holothuroidea with Crinoidea being absent. Holothuroidea were excluded from examinations due to lack of locality data. In addition, Plococidaris verticillata (de Lamarck, 1816) is a new distribution record for South Africa. This paper gives new accession numbers of the specimens and the only photographic record of this collection.
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Caecilians are enigmatic limbless amphibians that, with a few exceptions, all have an at least partly burrowing lifestyle. Although it has been suggested that caecilian evolution resulted in sturdy and compact skulls as an adaptation to their head-first burrowing habits, no relationship between skull shape and burrowing performance has been demonstrated to date. However, the unique dual jaw-closing mechanism and the osteological variability of their temporal region suggest a potential relationship between skull shape and feeding mechanics. Here, we explored the relationships between skull shape, head musculature and in vivo bite forces. Although there is a correlation between bite force and external head shape, no relationship between bite force and skull shape could be detected. Whereas our data suggest that muscles are the principal drivers of variation in bite force, the shape of the skull is constrained by factors other than demands for bite force generation. However, a strong covariation between the cranium and mandible exists. Moreover, both cranium and mandible shape covary with jaw muscle architecture. Caecilians show a gradient between species with a long retroarticular process associated with a large and pennate-fibered m. interhyoideus posterior and species with a short process but long and parallel-fibered jaw adductors. Our results demonstrate the complexity of the relationship between form and function of this jaw system. Further studies that focus on factors such as gape distance or jaw velocity will be needed in order to fully understand the evolution of feeding mechanics in caecilians.
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RBINS Staff Publications 2021
