New papers:
First record of this European temnospondyl family Micromelerpetidae in Africa
Stratigraphically oldest record of tetrapods in the Maghreb
Moroccan micromelerpetid skeletons assigned to new species Branchierpeton saberi
Long-distance migration of aquatic temnospondyls in Variscan mountain belt
Abstract
Recent fieldwork in late Carboniferous (Kasimovian) continental sediments of the Souss Basin, south-central Morocco, yielded two skeletons of small branchiosaur-like micromelerpetids. It is the first record of this European dissorophoid temnospondyl family in Africa and the stratigraphically oldest record of tetrapods in the Maghreb. The Moroccan micromelerpetid skeletons are assigned to the new species Branchierpeton saberi which is specifically unique by five cranial characters combined with a distinct shape of humerus and interclavicle. The new African micromelerpetid suggests that long-distance migration in the late Paleozoic Variscan mountain belt was possible even for small, mainly aquatic temnospondyls. The new Branchierpeton species might be of biostratigraphic value as a Kasimovian index fossil.
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The early Permian karst deposits near Richards Spur, Oklahoma, preserve a diverse assemblage of terrestrial dissorophoid temnospondyls in an upland environment. The dissorophids, an armored dissorophoid clade, were previously represented only by two species of the eucacopine Cacops, Cacops morrisi and Cacops woehri, a genus also known from the lowland floodplains of the Texas red beds by the genotype C. aspidephorus. Here we report the first documented occurrences of two other dissorophid taxa at Richards Spur, Aspidosaurus and Dissorophus, identified on the basis of their distinctive osteoderms. Similar to Cacops, both taxa are also known from the Texas red beds and other lowland Permo-Carboniferous localities. Their documentation increases both the dissorophoid diversity at Richards Spur and the faunal overlap between the tetrapod assemblage at Richards Spur and the classic early Permian localities of North America. Additional cranial and postcranial material is referred to C. morrisi, to a previously reported indeterminate dissorophine, and to C. woehri, the knowledge of which is greatly expanded through this report. Analysis of several osteoderm morphotypes using neutron tomography reveals information that both strengthens taxonomic referrals (e.g., bifurcated ventral flange in Dissorophus) and reveals unexpected new insights into dissorophid osteoderm variation (ventral flange of the internal series in Cacops; presence of an internal series in Aspidosaurus). The extensive diversity of terrestrial dissorophoids at this site is unparalleled and furthers the interpretation of the assemblage as a unique early Permian paleocommunity produced by distinct environmental conditions.
Loredana Macaluso, ÂGiorgio Carnevale, ÂRaffaello Casu, ÂDaniel Pietrocola, Andrea Villa & ÂMassimo Delfino (2019)
Structural and environmental constraints on reduction of paired appendages among vertebrates.
Biological Journal of the Linnean Society, blz097 (advance online publication)
doi:
https://doi.org/10.1093/biolinnean/blz097https://academic.oup.com/biolinnean/advance-article-abstract/doi/10.1093/biolinnean/blz097/5540011Burrowing habits or complex environments have generally been considered as potential drivers acting on reduction and loss of the appendicular skeleton among vertebrates. Herein, we suggest that this might be the case for lissamphibians and squamates, but that fin loss in fishes is usually prevented by important structural constraints, because pectoral fins are commonly used to control rolling and pitching. We provide an overview of the distribution of paired appendage reduction across vertebrates while examining the ecological affinities of finless and limbless clades. We analysed the correlation between lifestyle and fin or limb loss using the discrete comparative analysis. The resulting Bayesian factors indicate strong evidence of correlation between: (1) pectoral-fin loss and coexistence of anguilliform elongation and burrowing habits or complex habitat in teleost fishes; and (2) limb loss and a burrowing or grass-swimming lifestyle in squamate reptiles and lissamphibians. These correlations suggest that a complex environment or a fossorial habit is a driving force leading to appendage loss. The only style of locomotion that is functional even in the absence of paired appendages is the undulatory one, which is typical of all elongated reptiles and lissamphibians, but certainly less common in teleost fishes.