The pareiasaur fossil record in China is poor compared to that of Russia or South Africa. A new pareiasaur specimen is here reported from the upper Permian Naobaogou Formation of the Daqing Mountains, Nei Mongol, China. It is recognized as a new species of Elginia, a taxon otherwise known only from the upper Permian Cutties Hillock Sandstone of Scotland. Diagnostic features include a moderately developed cheek flange; prominent otic notch (formed between squamosal and quadratojugal at the posterior margin of the temporal plate); enlarged supraorbital bosses on prefrontal, postfrontal and postorbital; a hypertrophied supratemporal horn, and squamosal horn prominently projecting posteriorly from caudal margin of temporal plate. The new taxon is differentiated from E. mirabilis by a well-developed and crescentic postfrontal boss, which is the largest among a series of circumorbital bosses; upper orbital border distinctly domed with a smooth rather than angled anterodorsal margin; lesser developed cranial bosses, basal confluence of the transverse process and postzygapophysis forms a horizontal flange in some dorsal vertebrae. The new discovery significantly extends the geographical distribution of Elginia and Elginiidae.
Ichniotherium tracks with a relatively short pedal digit V (digit length ratio V/IV < 0.6) form the majority of yet described Late Carboniferous to Early Permian diadectomorph tracks and can be related to a certain diadectid clade with corresponding phalangeal reduction that includes Diadectes and its close relatives. Here we document the variation of digit proportions and trackway parameters in 25 trackways (69 step cycles) from nine localities and seven further specimens with incomplete step cycles from the type locality of Ichniotherium cottae (Gottlob quarry) in order to find out whether this type of Ichniotherium tracks represents a homogeneous group or an assemblage of distinct morphotypes and includes variability indicative for evolutionary change in trackmaker locomotion. According to our results, the largest sample of tracks from three Lower Permian sites of the Thuringian Forest, commonly referred to Ichniotherium cottae, is not homogeneous but shows a clear distinction in pace length, pace angulation, apparent trunk length and toe proportions between tracks from Bromacker quarry and those from the stratigraphically older sites Birkheide and Gottlob quarry. Three Late Carboniferous trackways of Ichniotherium with relatively short pedal digit V from Haine's Farm, Ohio, and Alveley near Birmingham, United Kingdom, that have been referred to the ichnotaxa "Baropus hainesi", "Megabaropus hainesi" and "Ichniotherium willsi", respectively, share a marked outward rotation of foot imprints with respect to walking direction. Apart from this feature they are in many aspects similar to the Birkheide and Gottlob records of Ichniotherium cottae. With the possible exception of the Maroon Formation (Early Permian, Colorado) sample, Early Permian Ichniotherium trackways with a relatively short pedal digit V fall into the morphological spectrum of the three well defined 'Hainesi-Willsi', 'Birkheide-Gottlob' and 'Bromacker' morphotypes. With their more obtuse pace angulations and higher body-size-normalized pace and stride lengths the Bromacker type tracks imply higher walking speeds of their trackmakers compared to all other Ichniotherium tracks. More generally, a trend towards higher locomotion capability from the last common ancestor of all Ichniotherium producers to the last common ancestor of all "Ichniotherium with relatively short pedal digit V" and from the latter to the trackmakers of the mid-Early Permian Bromacker type can be deduced â with the reservation that overall sample size is relatively small, making this scenario a preliminary assessment. Whether the presumed advancements represent a more general pattern within diadectomorphs, remains open until the non-European Ichniotherium trackway record improves. Ichnotaxonomic implications are discussed.
Meagan M. Gilbert, Emily L. Bamforth, Luis A. Buatois & Robin W.
Paleoecology and sedimentology of a vertebrate microfossil assemblage
from the easternmost Dinosaur Park Formation (Late Cretaceous, Upper
Campanian,) Saskatchewan, Canada: Reconstructing diversity in a coastal
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online
Presents the first description of a Campanian-aged (Late Cretaceous)
terrestrial microvertebrate site in Saskatchewan
Several described taxa extend the spatial range of species known from
the Dinosaur Park Formation in Alberta.
Several lines of evidence suggest the site was deposited in a marginal
marine environment undergoing regional transgression.
Illustrates how microvertebarte sites can be a source of as
A ~42âm section of Late Cretaceous Upper Campanian sediments in
Saskatchewan Landing Provincial Park, southwestern Saskatchewan, Canada,
represents the easternmost outcrop of the Dinosaur Park Formation in the Western
Interior Basin. Herein we document a new microvertebrate locality from the
upper part of this formation that shows high diversity in a mixed coastal and
marine assemblage. Palynology, ichnology, sedimentology, and vertebrate
palaeontology are integrated to determine paleoenvironmental and
paleoecological conditions in the region. The site is interpreted as having
been deposited under marginal-marine conditions near a shoreline undergoing
transgression by the encroaching Bearpaw Sea. Though well studied and sampled
in Alberta, the Dinosaur Park Formation is poorly exposed with little known
associated vertebrate assemblages in Saskatchewan. These discoveries from the
new microvertebrate site offer new insights into Late Cretaceous ecosystems
near paleocoastlines, allowing for future studies of spatial diversity patterns
relative to Albertan faunas. Herein is also presented the first published
occurrences of several Late Campanian vertebrate taxa in Saskatchewan.
Not fossil but will be useful in studying evolution...
Sergej Nowoshilow, Siegfried Schloissnig, Ji-Feng Fei, Andreas Dahl, Andy W. C. Pang, Martin Pippel, Sylke Winkler, Alex R. Hastie, George Young, Juliana G. Roscito, Francisco Falcon, Dunja Knapp, Sean Powell, Alfredo Cruz, Han Cao, Bianca Habermann, Michael Hiller, Elly M. Tanaka & Eugene W. Myers (2018)
The axolotl genome and the evolution of key tissue formation regulators.
Nature (advance online publication)Â
Salamanders serve as important tetrapod models for developmental, regeneration and evolutionary studies. An extensive molecular toolkit makes the Mexican axolotl (Ambystoma mexicanum) a key representative salamander for molecular investigations. Here we report the sequencing and assembly of the 32-gigabase-pair axolotl genome using an approach that combined long-read sequencing, optical mapping and development of a new genome assembler (MARVEL). We observed a size expansion of introns and intergenic regions, largely attributable to multiplication of long terminal repeat retroelements. We provide evidence that intron size in developmental genes is under constraint and that species-restricted genes may contribute to limb regeneration. The axolotl genome assembly does not contain the essential developmental gene Pax3. However, mutation of the axolotl Pax3 paralogue Pax7 resulted in an axolotl phenotype that was similar to those seen in Pax3â/â and Pax7â/â mutant mice. The axolotl genome provides a rich biological resource for developmental and evolutionary studies.