Ben Creisler
Some recent non-dino papers:
Now out in English (posted with Russian link earlier):
D. I. Pashchenko, I. T. Kuzmin, A. G. Sennikov, P. P. Skutschas & M. B. Efimov (2018)
On the Finding of Neosuchians (Neosuchia, Crocodyliformes) in the Middle Jurassic (Bathonian) Deposits of the Moscow Region.
Paleontological Journal 52(5): 550â562
Remains of neosuchian crocodyliforms (isolated teeth, fragment mandibular bone) from the Middle Jurassic (Bathonian) Peski locality in the Moscow Region are described for the first time. The neosuchian from Peski is characterized by well-pronounced ornamentation on the dermal skull bones, and also bicarinate teeth oval in cross section without serration and with triangular conical crowns and fine striation of the enamel. The similarity of Bathonian vertebrate faunas of the Moscow Region, Great Britain, Western Siberia, and Kyrgyzstan is evidence of homogeneity of the vertebrate fauna throughout Laurasia.
====
Free pdf:
K.S. Myrvold, J. MilÃn& J.A. Rasmussen (2018)
Two new finds of turtle remains from the Danian and Selandian (Paleocene) deposits of Denmark with evidence of predation by crocodilians and sharks.
Bulletin of the Geological Society of Denmark 66: 211â218
Free pdf:
Two new fragments of a turtle carapace and a turtle plastron (hypoplastron) have been recovered from glacially transported boulders of Danian and Selandian age. The hypoplastron is identified as Ctenochelys cf. stenoporus, while the carapace fragment can only be assigned to the family Cheloniidae indet. Both specimens show evidence of predation by crocodilians in the form of rows of circular pits in the bones, and one specimen has rows of elongated scrape traces interpreted as scavenging by sharks. Together with the other, rare finds from the middle Danian of the Faxe Quarry and from late Danian deposits in the Copenhagen area, these new finds add important new knowledge to the sparse fossil record of turtles in Scandinavia, as well as evidence that the genus Ctenochelys survived across the K/Pg Boundary.
====
Julia L. Molnar, Rui Diogo , John R. Hutchinson & Stephanie E. Pierce (2018)
Evolution of hindlimb muscle anatomy across the tetrapod waterâtoâland transition, including comparisons with forelimb anatomy.
The Anatomical Journal (advance online publication)
Tetrapod limbs are a key innovation implicated in the evolutionary success of the clade. Although musculoskeletal evolution of the pectoral appendage across the finsâtoâlimbs transition is fairly well documented, that of the pelvic appendage is much less so. The skeletal elements of the pelvic appendage in some tetrapodomorph fish and the earliest tetrapods are relatively smaller and/or qualitatively less similar to those of crown tetrapods than those of the pectoral appendage. However, comparative and developmental works have suggested that the musculature of the tetrapod forelimb and hindlimb was initially very similar, constituting a âsimilarity bottleneckâ at the finsâtoâlimbs transition. Here we used extant phylogenetic bracketing and phylogenetic character optimization to reconstruct pelvic appendicular muscle anatomy in several key taxa spanning the finsâtoâlimbs and waterâtoâland transitions. Our results support the hypothesis that transformation of the pelvic appendages from finâlike to limbâlike lagged behind that of the pectoral appendages. Compared to similar reconstructions of the pectoral appendages, the pelvic appendages of the earliest tetrapods had fewer muscles, particularly in the distal limb (shank). In addition, our results suggest that the first tetrapods had a greater number of muscleâmuscle topological correspondences between the pectoral and pelvic appendages than tetrapodomorph fish had. However, ancestral crownâgroup tetrapods appear to have had an even greater number of similar muscles (both in terms of number and as a percentage of the total number of muscles), indicating that the main topological similarity bottleneck between the paired appendages may have occurred at the origin of the tetrapod crown group.
====
Lauren Sallan, Matt Friedman, Robert S. Sansom, Charlotte M. Bird & Ivan J. Sansom (2018)
The nearshore cradle of early vertebrate diversification.
Science 362(6413): 460-464
DOI: 10.1126/science.aar3689
Shallow-water diversification
Most of what we know about the relationship between diversification and environment in ancient marine environments has come from invertebrates. The influence of habitat on vertebrate diversification thus remains a persistent question. Sallan et al. studied fossil vertebrates spanning the mid-Paleozoic, including both jawed and jawless fish (see the Perspective by Pimiento). They found that diversification occurred primarily in nearshore environments, with diversified forms later colonizing deeper marine or freshwater habitats. Furthermore, more robust forms remained in the nearshore, whereas more gracile forms moved to deeper waters. This split is similar to current relationships between form and environment in aquatic habitats.
Abstract
Ancestral vertebrate habitats are subject to controversy and obscured by limited, often contradictory paleontological data. We assembled fossil vertebrate occurrence and habitat datasets spanning the middle Paleozoic (480 million to 360 million years ago) and found that early vertebrate clades, both jawed and jawless, originated in restricted, shallow intertidal-subtidal environments. Nearshore divergences gave rise to body plans with different dispersal abilities: Robust fishes shifted shoreward, whereas gracile groups moved seaward. Fresh waters were invaded repeatedly, but movement to deeper waters was contingent upon form and short-lived until the later Devonian. Our results contrast with the onshore-offshore trends, reef-centered diversification, and mid-shelf clustering observed for benthic invertebrates. Nearshore origins for vertebrates may be linked to the demands of their mobility and may have influenced the structure of their early fossil record and diversification.
*****
Catalina Pimiento (2018)
Our shallow-water origins.
Science 362(6413): 402-403
DOI: 10.1126/science.aau8461
Vertebrates encompass all animals with a backbone, from fish to humans. How and when they evolved are questions that have been studied for centuries, revealing the origins and processes involved in anatomical innovations such as jaws, teeth, and paired appendages (1). A less explored, but equally important question is where they evolved. On page 460 of this issue, Sallan et al. (2) compile a new database of early occurrences (mid-Paleozoic, 490 to 360 million years ago) and site-specific environmental information to reconstruct vertebrate ancestral habitats. They report that all major vertebrate clades originated in restricted, shallow-water environments.
==
News:
===
===
Ulrich Riller, Michael H. Poelchau, Auriol S. P. Rae, Felix M. Schulte, Gareth S. Collins, H. Jay Melosh, Richard A. F. Grieve, Joanna V. Morgan, Sean P. S. Gulick, Johanna Lofi, Abdoulaye Diaw, Naoma McCall, David A. Kring & IODPâICDP Expedition 364 Science Party (2018)
Rock fluidization during peak-ring formation of large impact structures.
Nature 562: 511â518
Large meteorite impact structures on the terrestrial bodies of the Solar System contain pronounced topographic rings, which emerged from uplifted target (crustal) rocks within minutes of impact. To flow rapidly over large distances, these target rocks must have weakened drastically, but they subsequently regained sufficient strength to build and sustain topographic rings. The mechanisms of rock deformation that accomplish such extreme change in mechanical behaviour during cratering are largely unknown and have been debated for decades. Recent drilling of the approximately 200-km-diameter Chicxulub impact structure in Mexico has produced a record of brittle and viscous deformation within its peak-ring rocks. Here we show how catastrophic rock weakening upon impact is followed by an increase in rock strength that culminated in the formation of the peak ring during cratering. The observations point to quasi-continuous rock flow and hence acoustic fluidization as the dominant physical process controlling initial cratering, followed by increasingly localized faulting.
News: