Morphology of the petrosal and stapes of Borealestes (Mammaliaformes, Docodonta) from the Middle Jurassic of Skye, Scotland

We describe, in unprecedented detail, the petros-als and stapes of the docodont Borealestes from the Middle Jurassic of Scotland, using high resolution lCT and phase- contrast synchrotron imaging. We describe the inner ear endocast and the vascularized interior structure of the pet-rosal, and provide the first endocranial view of a docodontan petrosal. Our study confirms some similarities in petrosal and stapedial morphology with the better known Haldan-odon of the Late Jurassic of Portugal, including: (1) the degree of curvature of the cochlea; (2) multiple features related to the highly pneumatized paroccipital region; (3) the shape of lateral trough, the fossa of the M. tensor tym-pani, and the ridge on the promontorium; (4) the round shape of the fenestra vestibuli; and (5) overall morphology of the stapes. But Borealestes differs from Haldanodon in having a bony ridge that separates the tympanic opening of the prootic canal, the secondary facial foramen and the hia-tus Fallopii, from the fenestra vestibuli. We identify two new vascular structures: the anterior and posterior trans-cochlear sinuses, which traverse the pars cochlearis around the cochlear nerve (VIII). These trans-cochlear sinuses have not been observed in previous docodont specimens, and could be an autapomorphy of Borealestes, or apomorphic for this clade. We also establish the anatomical relationship of the circum-promontorium plexus to the inner endocast. The high quality of our scans has made these structures visible for the first time

Adaptive diversity of incisor enamel microstructure in South American burrowing rodents (family Ctenomyidae, Caviomorpha)

The aim of this study was to analyse the morphofunctional and adaptive significance of variation in the upper incisor enamel microstructure of South American burrowing ctenomyids and other octodontoid taxa. We studied the specialized subterranean tooth-digger †Eucelophorus chapalmalensis (Pliocene – Middle Pleistocene), and compared it with other fossil and living ctenomyids with disparate digging adaptations, two fossorial octodontids and one arboreal echimyid. Morphofunctionally significant enamel traits were quite similar among the species studied despite their marked differences in habits, digging behaviour and substrates occupied, suggesting a possible phylogenetic constraint for the Octodontoidea. In this context of relative similarity, the inclination of Hunter–Schreger bands, relative thickness of external index (EI) and prismless enamel zone were highest in †Eucelophorus, in agreement with its outstanding craniomandibular tooth-digging specialization. Higher inclination of Hunter–Schreger bands reinforces enamel to withstand high tension forces, while high external index provides greater resistance to wear. Results suggest increased frequency of incisor use for digging in †Eucelophorus, which could be related to a more extreme tooth-digging strategy and/or occupancy of hard soils. Higher external index values as recurring patterns in distant clades of tooth-digging rodents support an adaptive significance of this enamel trait

A high-resolution three-dimensional reconstruction of a fossil forest (Upper Jurassic Shishugou Formation, Junggar Basin, Northwest China)

This study focuses on the three-dimensional (3D) reconstruction of an Late Jurassic fossil forest based on a fossil assemblage located in the Shishugou Formation near Jiangjunmiao, north-eastern Junggar Basin, Xinjiang Uygur Autonomous Region, Northwest China. On the basis of tree stumps found in growth position together with published data on megaplant fossils, seeds and spores, a highresolution digital computer model, including different forest layers, was developed. In a study area of 31,500 m, 65 tree stumps with diameters between 0.2 and 2.9 m were mapped and subsequently used for the 3D reconstruction. The forest grew under moist conditions, probably close to the banks of an anastomosing river and consisted primarily of conifers, in particular Araucariaceae. Even though the tree density of the forest is only 22 trees/ha, the 3D reconstruction indicates a relatively closed canopy. Megaplant fossils and spores also show evidence for the presence of Angiopteris, Osmunda and Coniopteris, which were then used to reconstruct the understory of the forest. The trees were modelled in three different growth stages, representing young, older and mature trees, respectively. The growth parameters of individual trees and ferns were randomized in order to avoid duplications within the reconstruction. Detailed textures of leaves, fronds and bark were created to give the plants a more realistic appearance than that in previously published 3D reconstructions of fossil forest assemblages. Estimations of net biomass (approximately 9 tons/ha), annual biomass production and a calculation of nearest neighbour index (0.86) suggest an open forest with spatially distributed trees

An exceptional P-H phosphonite: Biphenyl-2,2'-bisfenchylchlorophosphite and derived ligands (BIFOPs) in enantioselective copper-catalyzed 1,4-additions

Biphenyl-2,2'-bisfenchol (BIFOL) based chlorophosphite, BIFOP-Cl, exhibits surprisingly high stabilities against hydrolysis as well as hydridic and organometallic nucleophiles. Chloride substitution in BIFOP-Cl proceeds only under drastic conditions. New enantiopure, sterically demanding phosphorus ligands such as a phosphoramidite, a phosphite and a P-H phosphonite (BIFOP-H) are hereby accessible. In enantioselective Cu-catalyzed 1,4-additions of ZnEt(2 )to 2-cyclohexen-1-one, this P-H phosphonite (yielding 65% ee) exceeds even the corresponding phosphite and phosphoramidite