Frederik Spindler, Ralf Werneburg & JÃrg W. Schneider (2019)
A new mesenosaurine from the lower Permian of Germany and the postcrania of Mesenosaurus: implications for early amniote comparative osteology.
PalZ (advance online publication)
Based on an exceptionally well-preserved articulated postcranial skeleton, the early amniote Cabarzia trostheidei gen. et sp. nov. is described. As the lack of the skull hampers its taxonomic assignment, a large sample of basal amniotes is included as part of an exhaustive comparison. Considering the slender, long-limbed proportions of the skeleton, several potential determinations are suggested in order to test for bolosaur, millerettid, araeoscelid, basal neodiapsid, or synapsid affinities. Numerous character conditions are re-evaluated regarding their distributions among early amniote subclades. The closest match to Cabarzia is found to be the middle Permian Mesenosaurus from Russia. The documentation for both genera provides the most complete postcranial descriptions of non-varanodontine varanopids. One of the main differences from Mesenosaurus is the curved ungual phalanx, indicating a use related to predatory behavior. An investigation of limb proportions, such as slender trunks, elongated hindlimbs, and relatively short forelimbs, may suggest the occurrence of facultative bipedalism in Mesenosaurus and Cabarzia. The oldest known mesenosaurine, C. trostheidei from the Asselian/Sakmarian, also pushes back the oldest evidence of bipedal locomotion by more than 15 Ma.
Angela C. Milner (2019)Â
A morphological revision of Keraterpeton, the earliest horned nectridean from the Pennsylvanian of England and Ireland.
Transactions of The Royal Society of Edinburgh (advance online publication)
The aquatic diplocaulid nectridean Keraterpeton galvani is the commonest taxon represented in the Jarrow Coal assemblage from Kilkenny, Ireland. The Jarrow locality has yielded the earliest known Carboniferous coal-swamp fauna in the fossil record and is, therefore, of importance in understanding the history and diversity of the diplocaulid clade. The morphology of Keraterpeton is described in detail with emphasis on newly observed anatomical features. A reconstruction of the palate includes the presence of interpterygoid vacuities and new morphological details of the pterygoid, parasphenoid and basicranial region. The hyoid apparatus comprising an ossified basibranchial element has not been reported previously in nectrideans. The structure of the scapulocoracoid and primitive nature of the humerus is described and the presence of a five-digit manus confirmed. Previously unrecognised accessory dermal ossifications are present in the pectoral girdle. Keraterpeton longtoni from the Bolsovian in Staffordshire, England, is also described and newly figured. The primitive condition in diplocaulids is defined on the basis of the earliest occurrence at Jarrow and discussed in relation to functional morphology and mode of life. The evolution of the diplocaulid clade is assessed in relation to the revised diagnoses that define the primitive condition in Keraterpeton.