Ben Creisler
Some recent non-dino amphibian stuff...
Special issue of Earth and Environmental Science Transactions of The Royal Society of Edinburgh
A Legacy in Fossils: a Tribute to Stan Wood
Volume 108 - Issue 1 - July 2018
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Mesanerpeton woodi gen. et sp. nov.Â
Timothy R. Smithson and Jennifer A. Clack (2018)
A new tetrapod from Romer's Gap reveals an early adaptation for walking.
Earth and Environmental Science Transactions of The Royal Society of Edinburgh 108(1): 89-97
A new early tetrapod, Mesanerpeton woodi gen. et sp. nov., collected by Stan Wood from the Ballagan Formation, Tournaisian CM palynozone, at Willie's Hole, Scottish Borders, is described. It includes vertebrae like those of Crassigyrinus, with poorly developed neural arches, a well ossified ulna with a large olecranon, and a humerus that is structurally intermediate between the pleisiomorphic condition of Devonian taxa and that of all later forms. A comparative analysis of this new material and other tetrapodomorph humeri revealed how an increase in humeral torsion transformed the course of the brachial artery and median nerve through the bone, from an entirely ventral path to one in which the blood vessel and nerve passed through the entepicondyle from the dorsal to the ventral surface. Increasing humeral torsion is suggested to improve walking in early tetrapods by potentially contributing to an increase in stride length, and is one of a number of changes to limb morphology during the Early Carboniferous that led to the development of terrestrial locomotion.
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Jennifer A. Clack, Laura B. Porro & Carys E. Bennett (2018)
A Crassigyrinus-like jaw from the Tournaisian (Early Mississippian) of Scotland.
Earth and Environmental Science Transactions of The Royal Society of Edinburgh 108(1): 37-46
The early tetrapod Crassigyrinus scoticus was a large aquatic predator from the mid Carboniferous (late VisÃan or early Serpukovian) of Scotland, around 330 My in age. There are five main specimens with cranial remains: an articulated skeleton; two incomplete skulls; and two lower jaws. Crassigyrinus retains several apparently primitive features of the palatal dentition and lower jaw, and its phylogenetic position is disputed. A partial lower jaw resembling that of Crassigyrinus was discovered at Burnmouth in the Borders region of Scotland. The horizon in which it was found is dated as late Tournaisian, CM palynozone, around 350 My in age. Though it lacks dentition, the jaw preserves much of the postsplenial, angular and surangular, whose appearance externally and internally is almost identical to that of C. scoticus. Internally, the jaw shows a similarly limited extent of the suturing between the splenial series and the prearticular, a primitive condition. Externally, the type and distribution of dermal ornamentation closely matches that of C. scoticus, as does the deeply excavated and marginally positioned lateral line groove. As well as external and internal features, all specimens of C. scoticus are of similar skull size, though the Burnmouth jaw is somewhat smaller. If correctly attributable to Crassigyrinus, this specimen extends the existence of the genus by approximately 20 million years towards the base of the Carboniferous.
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Some additional amphibian evolution stuff that may of interest to some:
Free pdf:
Michael Veith, Sergà Bogaerts, Frank Pasmans & Sarah Kieren (2018)
The changing views on the evolutionary relationships of extant Salamandridae (Amphibia: Urodela)
PLoS ONE 13(8): e0198237.
The phylogenetic relationships among members of the family Salamandridae have been repeatedly investigated over the last 90 years, with changing character and taxon sampling. We review the changing composition and the phylogenetic position of salamandrid genera and species groups and add a new phylogeny based exclusively on sequences of nuclear genes. Salamandrina often changed its position depending on the characters used. It was included several times in a clade together with the primitive newts (Echinotriton, Pleurodeles, Tylototriton) due to their seemingly ancestral morphology. The latter were often inferred as a monophyletic clade. Respective monophyly was almost consistently established in all molecular studies for true salamanders (Chioglossa, Lyciasalamandra, Mertensiella, Salamandra), modern Asian newts (Cynops, Laotriton, Pachytriton, Paramesotriton) and modern New World newts (Notophthalmus, Taricha). Reciprocal non-monophyly has been established through molecular studies for the European mountain newts (Calotriton, Euproctus) and the modern European newts (Ichthyosaura, Lissotriton, Neurergus, Ommatotriton, Triturus) since Calotriton was identified as the sister lineage of Triturus. In pre-molecular studies, their respective monophyly had almost always been assumed, mainly because a complex courtship behaviour shared by their respective members. Our nuclear tree is nearly identical to a mito-genomic tree, with all but one node being highly supported. The major difference concerns the position of Calotriton, which is no longer nested within the modern European newts. This has implications for the evolution of courtship behaviour of European newts. Within modern European newts, Ichthyosaura and Lissotriton changed their position compared to the mito-genomic tree. Previous molecular trees based on seemingly large nuclear data sets, but analysed together with mitochondrial data, did not reveal monophyly of modern European newts since taxon sampling and nuclear gene coverage was too poor to obtain conclusive results. We therefore conclude that mitochondrial and nuclear data should be analysed on their own.
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Free pdf:
Jia Jia, Zhang Meihua, Ke-Qin Gao & Jiang Jianping (2018)
Dataset of ÎCT scan of the holotype specimen of Batrachuperus londongensis Liu and Tian, 1978, an endemic hynobiid (Amphibia, Urodela) from Mount Emei, Sichuan Province, China.
China Scientific Data 3(2):
DOI: 10.11922/csdata.2018.0005.zh
Dataset DOI: 10.11922/sciencedb.557
As a primitive clade of tailed amphibians, hynobiids are significant in understanding the early evolutionary history of salamanders. However, no consensus has been reached in regard to the time and location of origin, evolutionary history of certain characters, and phylogenetic relationships of Hynobiidae, due to several factors including: poor fossil records, insufficient morphological investigations of living taxa, inconsistent results of cladistic analyses using molecular data, and lack of morphology-based phylogenetic analyses. Batrachuperus londongensis , living in the Longdong River area at Mount Emei, Sichuan Province, China, features as the single living hynobiid species that is facultatively neotenic. Despite that the species has been known to scientific community for 40 years, its osteology has not been thoroughly investigated. This paper provides the technical procedures of employing high resolution CT scan (ÎCT) technique in investigating the osteology of the holotype (CIB 14380) of Batrachuperus londongensis . ÎCT scan of the holotype specimen (CIB 14380) of B. londongensis was completed using the Quantum GX microCT Imaging System at Chengdu Institute of Biology, Chinese Academy of Sciences. The voxel size derived from these scans ranges between 67.1â144 Îm. Several distinctive osteological traits characterizing the neotenic individuals of B. londongensis were revealed, such as the highly ossified hyobranchial apparatus and wholly ossified carpals and tarsals in the limb. This study represents the first attempt of applying ÎCT scanning techniques in the osteological research of living hynobiids endemic in China. The dataset includes ÎCT source data of the holotype and associated parameter files; reconstructed images and videos displaying the cranial part and the whole skeleton; and a 3D pdf and 3D printable stl files for the cranial part of the holotype. The source data files created from the ÎCT scan display a clear outline of the skeleton and can be easily read by software, like VG Studio. This dataset benefits researchers and the public interested in the osteology of the facultatively neotenic Batrachuperus londongensis , and is valuable for investigating the morphology of hynobiids endemic in China.
