Lorenzo Marchetti (2016)
New occurrences of tetrapod ichnotaxa from the Permian Orobic Basin (Northern Italy) and critical discussion of the age of the ichnoassociation.
Papers in Palaeontology (advance online publication)
late Cisuralian (Artinskian–Kungurian) is a key time interval for Permian
tetrapod evolution. In all the main low-latitude Pangean sites, the fossil footprint
record clearly shows a diversification and dispersal of non-synapsid amniote
tracks compared to the early Cisuralian (Asselian–Sakmarian). However, data on
latest Cisuralian (i.e. late Kungurian) sites are quite fragmentary. A new
ichnotaxonomic study was carried out in the central part of the Orobic Basin,
where the highly-fossiliferous Pizzo del Diavolo formation crops out and can
potentially cover this gap in knowledge. The following tetrapod ichnogenera
were identified: Amphisauropus, Batrachichnus, cf. Dimetropus, Dromopus,
Erpetopus, Hyloidichnus, Limnopus, cf. Merifontichnus and Varanopus; they can
be attributed to seymouriamorph and temnospondyl amphibians; pelycosaur
synapsids; and diapsid, parareptile and captorhinid reptiles. Dimetropus and
Merifontichnus are identified for the first time in the Permian of Italy. The
ichnoassociation, in agreement with the radiometric dating of the underlying
Cabianca formation, suggests a late Kungurian (latest Cisuralian) age for the
Pizzo del Diavolo formation. It includes the youngest and most diverse
non-synapsid amniote ichnofauna of the Cisuralian with five different
ichnogenera and possibly six ichnospecies, and thus constitutes a key area for
the study of eureptile and parareptile dispersal at low latitudes
Michael Stein, Suzanne J. Hand & Michael Archer (2016)
A new crocodile displaying extreme constriction of the mandible, from the late Oligocene of Riversleigh, Australia.
Journal of Vertebrate Paleontology (advance online publication)
A new fossil crocodile, Ultrastenos willisi, is described from a cranium and postcranial materials collected from the Riversleigh World Heritage Area, northwestern Queensland, Australia. The mandible displays pronounced anterior constriction, approaching that seen in the extant gharial, Gavialis gangeticus, and false gharial, Tomistoma schlegelii. As such, U. willisi potentially filled the ecomorphological niche associated with longirostry that has been previously unaccounted for in Riversleigh's Oligo–Miocene crocodile fauna. The pronounced constriction and features of the posterior cranium further distinguish U. willisi from all other known crocodiles, including the only reported Australian Oligo–Miocene longirostral crocodile, Harpacochampsa camfieldensis, from Bullock Creek in the Northern Territory. Ultrastenos willisi is recognized as a new genus and species assigned to subfamily Mekosuchinae on the basis of phylogenetic analysis.
Saradee Sengupta , Dhurjati Prasad Sengupta & Saswati Bandyopadhyay (2016)
Stratigraphy of the upper Gondwana formations around Sohagpur, western part of the Satpura Gondwana Basin, Central India.
Journal of the Geological Society of India 87(5): 503-519
The present work provides a detailed lithological map of the western part of the Satpura basin around Sohagpur and reports the presence of new archosauromorph fossil bones from that region. The study area is dominated by the Bagra Formation along with a narrow patch of the underlying upper part of the Denwa Formation. The lower Denwa and the underlying Pachmarhi formations are absent here. The presence of the Pachmarhi Formation, as a tongue shaped area, as mapped by Crookshank (1936) is discarded in this study on the basis of lithology and petrographic analyses, instead the presence of the Bagra Formation is suggested in this area. A comparison of the lithologies and the vertebrate faunas of the upper Gondwana formations between eastern and western part of the basin has been carried out for the first time. The comparison indicates that the Denwa Formation present in the western sector represents only the topmost part of the formation while the complete succession of Denwa is preserved in the eastern sector. The Bagra Formation in the western sector documents the presence of sheet-like sandstone bodies unlike the eastern part. The vertebrate fauna of the eastern part is dominated by temnospondyl amphibians while that of the western part is dominated by archosauromorph. The vertebrate fossils of upper part of Denwa Formation, found from similar lithologies in west and east though, have differences in the amount of transportation before their burial.
Patrick J. Orr, Laetitia B. Adler, Susan R. Beardmore, Heinz Furrer, Maria E. McNamara, Enrique Peñalver-Mollá & Ragna Redelstorff (2016)
"Stick 'n' peel": Explaining unusual patterns of disarticulation and loss of completeness in fossil vertebrates.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
Most fossil vertebrate skeletons are incomplete and/or disarticulated; this is often the result of disturbance by water currents.
Existing taphonomic models emphasise the size, shape and density of bones when determining whether or not they will be transported in currents.
Decay fluids leaking from a carcass stick it to the substrate; bones on the downward-facing side are preferentially affected.
If subjected to a current, these bones are less likely to be removed than others; this anomaly, 'stick 'n peel', can impact significantly on the skeletal taphonomy of a carcass.
The phenomenon is common in the fossil record and can be identified retrospectively by a characteristic set of unusual taphonomic features.
Few fossil vertebrate skeletons are complete and fully articulated. Various taphonomic processes reduce the skeletal fidelity of decaying carcasses, the effects of most of which are reasonably well understood. Some fossil vertebrates, however, exhibit patterns of disarticulation and loss of completeness that are difficult to explain. Such skeletons are one of two variants. They are incomplete, often markedly so, but the preserved parts are highly articulated. Alternatively, they are complete, or nearly so, but articulation varies markedly between parts of the body. A characteristic feature is the absence of skeletal elements that, on the basis of their larger size and/or greater density, would be predicted to be present. Here we erect a model, termed "stick 'n' peel", that explains how these distinctive patterns originate. The model emphasizes the role of decay products, especially fluids released from the carcass while resting on the sediment surface. These fluids permeate the sediment below and around the carcass. As a result, skeletal elements on the downward facing side of the carcass become adhered to the sediment surface, and are less likely to be remobilized as a result of current activity than others. The pattern of articulation and, especially, completeness is thus not what would be predicted on the basis of the size, shape and density of the skeletal elements. The effects of stick ‘n’ peel are difficult to predict a priori. Stick ‘n’ peel has been identified in vertebrate fossils in lacustrine and marine settings and is likely to be a common feature of the taphonomic history of many vertebrate assemblages. Specimens becoming adhered to the substrate may also explain the preservation in situ of the multi-element skeletons of invertebrates such as echinoderms, and integumentary structures such as hair and feathers in exceptionally preserved fossils.