A new paper:
Chase D. Brownstein (2018)
A tyrannosauroid tibia from the Navesink Formation of New Jersey and its biogeographic and evolutionary implications for North American tyrannosauroids.
Cretaceous Research (advance online publication)
The sparse dinosaur record of eastern North America has rendered the dinosaurs of the Late Cretaceous landmass of Appalachia obscure. Appalachia may have been a refugium for dinosaur species which would be replaced on Appalachia's western contemporary, Laramidia, from which the former landmass was isolated by the Western Interior Seaway. Among the theropods of the landmass, Appalachian tyrannosaurs are only represented currently by the two valid taxa Dryptosaurus aquilunguis and Appalachiosaurus montgomeriensis, a distinct but indeterminate taxon from the Campanian of Delaware, and indeterminate skeletons and isolated elements. New Jersey in particular has rendered many bones assignable to tyrannosauroids, contributing much to the study of members of this clade from Appalachia. Here, the partial tibia of a tyrannosauroid is described from the Maastrichtian Navesink Formation of Monmouth County, New Jersey. The specimen, originally described by paleontologists Edward Drinker Cope and Joseph Leidy, is important for revealing further the theropod fauna of the Navesink Formation of New Jersey and being the second definite occurrence of a tyrannosauroid in eastern North America during the Maastrichtian, thus illuminating the group's ecology and biogeography during that stage of the Cretaceous. Phylogenetic analysis plots the Navesink specimen as the sister taxon to Bistahieversor in a larger polytomy of all tyrannosauroids more derived than Eotyrannus, suggesting that the Navesink bone may represent either another âintermediateâ-grade tyrannosauroid from Appalachia or a relative of B. sealeyi that migrated to eastern North America after the regression of the Western Interior Seaway.
Recent papers not yet mentioned:
Ana M. Bravo, Paloma Sevilla & Fernando Barroso-BarcenillaÂ Â(2018)
Avian and crocodilian eggshells from the upper Barremian site of Vadillos-1 (Lower Cretaceous, Cuenca province, Spain).
Cretaceous Research 85: 28â41
The new upper Barremian microfossil site of Vadillos-1 (Lower Cretaceous, Beteta Gorges, Cuenca province, Spain) has yielded a rich fossil assemblage consisting of numerous eggshell fragments along with diverse skeletal remains of fishes, amphibians, turtles, crocodyliforms and dinosaurs. Crocodilian eggshells constitute the main fraction of the eggshell assemblage which includes abundant material belonging to the oofamily Krokolithidae, as well as a new type of crocodilian eggshells (Neokrokolithes trigonalis oogen. et oosp. nov.) characterised by a type of ornamentation and microstructure of the basal knobs not described before. Few fragments of the oospecies cf. Mycomorphoolithus kohringi, attributed to non-eusuchian crocodylomorphs, have been also found in this site thus expanding the record of this oospecies to the upper Barremian. The eggshell assemblage has also yielded the first record of avian eggshells (Tristratioolithus minuta oogen. et oosp. nov.) from the Lower Cretaceous of Europe. Comparisons with Lower Cretaceous avian eggshells suggest its possible attribution to Enantiornithes. The tiny eggshell fragments assemblage found at Vadillos-1 site is representative of a small sized fauna. Besides, the diversity appears strongly biased with >90% of the eggshells belonging to crocodilians and approximately 9% to Aves. As established for similar outcrops, this bias may reflect differences in preservation of eggshell types or represent, at least in part, a wetland ground nesting site.
Dongxu Chen, Fengqi Zhang, Yuntao Tian, Zhonghe Zhou, Yildirim Dilek, Hanlin Chen, Kefeng Zhang & Xueqin Zhao (2018)
Timing of the late Jehol Biota: New geochronometric constraints from the Jixi Basin, NE China.
Palaeogeography, Palaeoclimatology, Palaeoecology 492: 41-49
The first tephra geochronological constraint to the late Jehol Biota.
Raising the upper age of the Jehol Biota in East Asia by 4â9 Myr.
Accurate age calibration for the diversified dicots in NE Asia.
The Jehol Biota is a world-famous Early Cretaceous terrestrial ecosystem in East Asia and has revealed exceptionally wellâpreserved fossils which provide significant insights into the origin and evolution of birds and feathers, and the early diversifications of mammals and angiosperms. After the long-lived controversies over the timing of the biota varying from Late Jurassic to Early Cretaceous in last century, the lifespan of the early-middle Jehol Biota has been precisely dated from Barremian to early Aptian (ca. 131â120 Ma) by a series of recent radiometric analyses. However, few wellâconstrained ages are available for the late Jehol Biota, hindering our complete understanding of the evolutionary history of the terrestrial ecosystem. Alternating marine and non-marine deposits of the Chengzihe Formation in eastern Heilongjiang have yielded a non-marine bivalve assemblage of the Jehol Biota, basal angiosperms, and Cretaceous marine index bivalves, which collectively offer crucial and indisputable clues against the prevailing Jurassic time of the biota since 1990s. Here we present the first discovery of tephra layers from the Chengzihe Formation, dated by zircon U-Pb geochronology as ca. 116â111 Ma, providing the first quantitative age calibration for the early angiosperms and the Jehol bivalve assemblage. Therefore, we demonstrate that the duration of the Jehol Biota extends to late Aptianâearly Albian, approximately 4â9 Myr younger than the currently accepted age limits.
TomÃs Luppo, MÃnica G. LÃpez de Luchi, Augusto E. Rapalini, Carmen I. MartÃnez Dopico & Christopher M. Fanning (2018)
Geochronologic evidence of a large magmatic province in northern Patagonia encompassing the Permian-Triassic boundary.
Journal of South American Earth Sciences (advance online publication)
A ca.~6âkm thick succession of volcanic and volcaniclastic rocks was recognized in Northern Patagonia.
U-Pb zircon ages (SHRIMP) define a 10 Ma period (257- 248) of concurrent magmatism across the Permian-Triassic boundary.
The Permo-Triassic Magmatic Province is enlarged to central Patagonia (Los Menucos- La Esperanza magmatic complexes).
Depocenters may have recorded the passage among the P-Tr mass extinction and the arise of Mesozoic life diversity paths.
The Los Menucos Complex (northern Patagonia) consists of ~6âkm thick succession of acidic and intermediate volcanic and pyroclastic products, which has been traditionally assigned to the Middle/Late Triassic. New U/Pb (SHRIMP) zircon crystallization ages of 257âÂâ2 Ma at the base, 252âÂâ2 Ma at an intermediate level and 248âÂâ2 Ma near the top of the sequence, indicate that this volcanic event took place in about 10 Ma around the Permian-Triassic boundary. This volcanism can now be considered as the effusive terms of the neighboring and coeval La Esperanza Plutono-Volcanic Complex. This indicates that the climax of activity of a large magmatic province in northern Patagonia was coetaneous with the end-Permian mass extinctions. Likely correlation of La Esperanza- Los Menucos magmatic province with similar volcanic and plutonic rocks across other areas of northern Patagonia suggest a much larger extension than previously envisaged for this event. Its age, large volume and explosive nature suggest that the previously ignored potential role that this volcanism might have played in climatic deterioration around the Permian-Triassic boundary should be investigated.