Influence of calcareous nodules content on scaling effect in shear strength of cohesive soil containing calcareous nodules

The difference in the shear strength and other characteristics of the cohesive soil containing calcareous nodules (CSCN) between samples with large size and corresponding scaling size, which is called scaling effect, is significantly affected by its calcareous nodule content (CNC) of the gradation composition. However, current researches rarely reveal the influence of the CNC on the scaling effect in shear strength of samples. In this study, how and why the CNC affects the scaling effect in shear strength were explored. Then a method to reduce the scaling effect based on the reason for influence was proposed. Results show that the correlation between the scaling effect in shear strength and the CNC presents a step curve. This is attributed to that it is easier to form a skeleton effect in samples with scaling size for the same CNC. Considering the skeleton effect, a calculation model for the shear strength parameters of CSCN samples with large size is proposed to reduce the scaling effect. This paper demonstrates that the proposed calculation model provides an access to obtain calculated shear strength parameters of CSCN samples with large size by using measured results of samples with corresponding scaling size.

Cranium of an Eocene/Oligocene pheasant-sized galliform bird from western North America, with the description of a vascular autapomorphy of the Galliformes

We describe the fossil cranium of a pheasant-sized galliform land bird from latest Eocene or earliest Oligocene marine rocks of the Jansen Creek Member, Makah Formation (Washington State, USA), which is the only three-dimensionally preserved cranium of a Paleogene representative of the Galliformes. The specimen was freed from a hard calcareous nodule with dilute formic acid. Micro-computed tomography provided further osteological details and a virtual cranial endocast. The fossil exhibits a plesiomorphic temporal morphology, lacking an ossified aponeurosis zygomatica, a feature characterizing some extant Cracidae and most Odontophoridae and Phasianidae. Overall, the fossil is most similar to the skull of the Asian phasianid taxon Arborophila, but this resemblance may well be plesiomorphic for a more inclusive clade. Still, we consider it possible that the fossil represents an archaic member of the Phasianoidea, in which case it would be the earliest record of this taxon from the New World. The fossil exhibits a previously unnoticed cranial autapomorphy of galliforms, a foramen in the temporal region that enables the vena profunda to enter the braincase, for which the name foramen temporale venosum is here introduced. Consistently present in all studied extant galliform taxa and absent in all other extant birds, this foramen enables a vascular connection between the brain and the ophthalmic rete, the latter playing an important role in thermoregulation of the avian brain.

Skeleton of a leopard frog (Rana pipiens) from Champlain Sea deposits (ca. 10 000 BP) near Eardley, Quebec

A well-preserved skeleton of a leopard frog (Rana pipiens) was recovered from a calcareous nodule collected near Eardley, Quebec. Such nodules from the Ottawa area evidently date to the Ottawa Delta phase of the Champlain Sea, ca. 10 000 BP, and may contain remains of fishes, birds, mammals, marine mollusc shells and other invertebrates, and plants. Palynological analysis of matrix from the specimen suggests either (1) that forest communities were prominent in the area where the frog lived, or (2) that, presuming the specimen was from a large body of water, the environment supported herb and shrub tundra communities with only a few trees. This is the first record of an amphibian from Champlain Sea deposits. The specimen indicates the presence of grassy meadows near the seacoast.

Paleoecology and distribution of the Early Cambrian rostroconch Watsonella crosbyi Grabau

Watsonella crosbyi Grabau, 1900, a senior synonym of Heraultipegma varensalense (Cobbold, 1935) and H. yannense He and Yang, 1982, is the oldest known rostroconch. The species ranges through most of the Early Cambrian and has been recovered from temperate siliciclastic (Avalon Platform) and tropical carbonate (south China, Mongolia?, southern France) environments. Watsonella crosbyi occurs through approximately 880 meters of the sub-trilobitic Lower Cambrian of southeastern Newfoundland. Its lowest occurrence corresponds to the first appearance of relatively diverse small shelly faunas of the pre-Tommotian Watsonella crosbyi Zone (new).The general form of Watsonella crosbyi conchs (laterally compressed, prosogyrate, elongate posterior, subdued comarginal growth lines, very thin shell with anterior and posterior gapes) is similar to that in a number of larger burrowing pelecypods, but this does not rule out other benthic habits. However, recovery of locally common in situ conchs (plane of commissure vertical, long axis subhorizontal) in the lower and upper parts of its stratigraphic range in southeastern Newfoundland corroborates an infaunal life habit for the species. The animal is a prominent element in faunas from offshore, cohesive, siliciclastic mudstones but also occurs in calcareous nodule-rich mudstones, shell hash limestones, and, infrequently, in peritidal algalaminate limestones. A phylogenetic sequence from laterally compressed monoplacophorans to early ribeiroid rostroconchs and leading to the oldest pelecypods was completed by the middle Early Cambrian and involved infaunal mollusks.

XII. On the structure of the Dicynodont skull

We propose in this communication to supplement our previous account of the Dicynodon ( D. leoniceps ? ) skull by some observations on another specimen of unknown species, for which we are indebted, through the kind offices of Dr. Smith Woodward, to the generosity of the Trustees of the British Museum. As is so commonly the case, this skull is included in a hard calcareous nodule, and thus inaccessible to systematic observation except by serial sections. It was found in the Karoo beds of South Africa.