Ben Creisler
Some new non-dino papers that may be of interest:
Conflicto antarcticus gen. & sp. nov.
Claudia P. Tambussi, Federico J. Degrange, Ricardo S, De Mendoza, Emilia Sferco & Sergrio Santillana
A stem anseriform from the early Palaeocene of Antarctica provides new key evidence in theÂ
Zoological Journal of the Linnean Society, zly085
A new Anseriformes, Conflicto antarcticus gen. et sp. nov., represented by associated bones of a single individual, from the early Palaeocene of Antarctica is described. The new taxon is unlike any other known member of the order. Conflicto antarcticus is a medium-sized (2 kg) stem anseriform. The forelimb and pectoral girdle bones suggest that it was a flying bird, and the bones of the hindlimb show that it had elongated legs. The os quadratum represents a unique combination of features; some are similar to the features of the ancestral quadrate for galloanserines and some are similar to Anseriformes, but features such as the presence of three foramina are exclusive among Neornithes. The incisura or foramen nervi suracoracoidei is absent in C. antarcticus, as in most anatids and all Galliformes. Phylogenetic analysis shows that C. antarcticus + Anatalavis oxfordi is the most basal stem Anseriformes clade. This implies that the duck-type beak must have developed at an early stage of anseriform evolution. Conflicto antarcticus represents one (and possibly the most) substantial record of a non-marine Palaeocene bird from the Southern Hemisphere and supports the hypothesis that Neognathae had already diversified in the earliest Palaeocene.
===
Free pdf:
Manja Voss, Mohammed Sameh M. Antar, Iyad S. Zalmout, Philip D. Gingerich (2019)
Stomach contents of the archaeocete Basilosaurus isis: Apex predator in oceans of the late Eocene.Â
PLoS ONE 14(1): e0209021.
Apex predators live at the top of an ecological pyramid, preying on animals in the pyramid below and normally immune from predation themselves. Apex predators are often, but not always, the largest animals of their kind. The living killer whale Orcinus orca is an apex predator in modern world oceans. Here we focus on an earlier apex predator, the late Eocene archaeocete Basilosaurus isis from Wadi Al Hitan in Egypt, and show from stomach contents that it fed on smaller whales (juvenile Dorudon atrox) and large fishes (Pycnodus mokattamensis). Our observations, the first direct evidence of diet in Basilosaurus isis, confirm a predator-prey relationship of the two most frequently found fossil whales in Wadi Al-Hitan, B. isis and D. atrox. This extends our understanding of their paleoecology. Late Eocene Basilosaurus isis, late Miocene Livyatan melvillei, and modern Orcinus orca are three marine apex predators known from relatively short intervals of time. Little is known about whales as apex predators through much of the Cenozoic era, and whales as apex predators deserve more attention than they have received.
==
Free pdf:
Manabu Sakamoto, Marcello Ruta and Chris Venditti (2019)
Extreme and rapid bursts of functional adaptations shape bite force in amniotes.
Proceedings of the Royal Society B: Biological Sciences 286 (1894): 20181932.
Free pdf:
Adaptation is the fundamental driver of functional and biomechanical evolution. Accordingly, the states of biomechanical traits (absolute or relative trait values) have long been used as proxies for adaptations in response to direct selection. However, ignoring evolutionary history, in particular ancestry, passage of time and the rate of evolution, can be misleading. Here, we apply a recently developed phylogenetic statistical approach using significant rate shifts to detect instances of exceptional rates of adaptive changes in bite force in a large group of terrestrial vertebrates, the amniotes. Our results show that bite force in amniotes evolved through multiple bursts of exceptional rates of adaptive changes, whereby whole groupsâincluding Darwin's finches, maniraptoran dinosaurs (group of non-avian dinosaurs including birds), anthropoids and hominins (fossil and modern humans)âexperienced significant rate increases compared to the background rate. However, in most parts of the amniote tree of life, we find no exceptional rate increases, indicating that coevolution with body size was primarily responsible for the patterns observed in bite force. Our approach represents a template for future studies in functional morphology and biomechanics, where exceptional rates of adaptive changes can be quantified and potentially linked to specific ecological factors underpinning major evolutionary radiations.