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Shell growth in Pecten conforms closely to a model where the shell margin is a sector of an ellipse (nearly circular), and where shell growth reflects an expansion and migration of the margin away from the shell apex. Detailed ontogenetic measurements on seven species (n = 23) indicate that all specimens are allometric, as reflected in both (1) a curvature of the ribs on the flattened left valve, and (2) a doming or vaulting of the coiled right valve. Patterns of covariation between growth parameters indicate that shell morphologies converge towards specific adult geometries.

• Read more about The structure of ontogenetic variation in the shell of Pecten

A new porolepiform, Duffichthys mirabilis gen. et sp. nov., is described from the Upper Fras locality of Scat Craig, near Elgin, Scotland. Duffichthys is a member of the Holoptychiidae, and snares derived characters with Glyptolepis, but has a unique lower-jaw morphology characterized by an extremely parasymphysial tooth plate attachment; two isolated parasymphysial tooth plates, probably belongit Duffichthys, differ from those of other known holoptychiids in carrying only a single fang.

• Read more about A new holoptychiid porolepiform fish from the Upper Frasnian of Elgin, Scotland

Alispira gracilis and Alispira tenuicostata previously have been known only from early Silurian rocks of the Siberian Platform and the eastern Baltic region. Here they are described from early Silurian (Llandovery) rocks of Canada, from the Beaverfoot Formation in the southern Rocky Mountains, the Nonda Formation in the northern Rocky Mountains (both British Columbia), and the Mount Kindle Formation in the District of Mackenzie. A third species, Alispira lowi, is described from the Severn River Formation in northern Manitoba.

• Read more about The Early Silurian atrypid brachiopod Alispira from western Canada

Dinosaur jaw remains from the Early Cretaceous Khok Kruat Formation of northeastern Thailand, including a well-preserved dentary and a maxilla fragment, are described as belonging to a new species of the primitive ceratopian Psittacosaurus, P. sattayaraki. It differs from previously described species of Psittacosaurus from Mongolia and China in the morphology of its dentary.

• Read more about A new species of the ornithischian dinosaur Psittacosaurus from the Early Cretaceous of Thailand

Sedimentary rocks of the Scotia Group, Prins Karls Forland, Svalbard, have been metamorphosed to lower greenschist facies. Yet Scotia chert nodules contain abundant organic-walled microfossils belonging to at least seventeen taxa. Their black colour indicates that the fossils underwent substantial thermal alteration. However, it is suggested that preservation in a matrix of early diagenetic silica shielded them from the most destructive mechanical and chemical effects of metamorphism.

• Read more about Vendian microfossils in metasedimentary cherts of the Scotia Group, Prins Karls Forland, Svalbard

The heteromorph ammonites (Ancyloceratina) from the Upper Maastrichtian Valudavur Formation (Valudayur Group, Anisoceras beds of authors) of Pondicherry, south India are revised in a sequel to the previously published account of the normally coiled Phylloceratina, Lytoceratina and Ammonitina. Twelve species referred to eight genera are recognized, of which Cyrtoptychoceras is a new representative of the Polyptychoceratinae. The fauna is of great importance in the development of heteromorph ammonite taxonomy, although a source of great confusion to previous workers.

• Read more about Heteromorph ammonites from the Upper Maastrichtian of Pondicherry, south India

In considering ventral shape and longitudinal sectional outline of the test in fourteen living spatanoid species, four types can be recognized: flat, globular, wedge-shaped, and domed, with two intermediate series. Although the basic arrangement of spines is common to all, differences in test profile impart different attitudes to the spines and hence affect their function for burrowing. Three different burrowing mechanisms are recognized, which are the consequence of specific test profiles. Each burrowing mechanism corresponds to a specific burrowing depth and to sediment grain size.

• Read more about Adaptation of test shape for burrowing and locomotion in spatangoid echinoids

The Chia Gara Formation consists of 125-232 m of thin-bedded limestones, marls and shales in the area between Zalkho and Amadia. Iraqi Kurdistan, north of Mosul. The formation ranges in age from the base of the Tithonian, where it is underlain by formations that contain a few Kimmeridgian ammonites, up to nearly the top of the Berriasian, where it is succeeded by the Garagu Formation, which contains uppermost Berriasian and Valangiman ammonites.

• Read more about Tithonian and Berriasian ammonites from the Chia Gara Formation in northern Iraq

The surface ornamentation of acrotretoid brachiopods includes three kinds of microstructural features which appear to reflect the nature of the periostracum and the outer mantle lobe responsible for secreting the first-formed layers of the phosphatic shell. Radial folds, less than 1 um in wavelength, must have been casts of wrinkles in a thick, inner sealing membrane of a vesicular periostracum. Coarser folds are discrete segments of concentric ridges (fila), disposed as outwardly convex arcs (drapes) with chords up to 40 um in length.

• Read more about Ornamentation and shell structure of acrotretoid brachiopods

Two species of nautiloid - a new genus and species of Cyclostomiceratidae and a new species of Dideroceras from the Llanvirn Series of Wales and western Shropshire - show preservational features which suggest that the adapical portions of the phragmocones imploded after the death of the organism. The limit of phragmocone damage is close to the most adoral development of siphonal diaphragms or endocones. It is thought that the apical part of the phragmocone was partly or completely filled with gas, failing to flood or flooding very slowly after the death of the organism.

• Read more about Phragmocone implosion in Ordovician nautiloids and the function of siphonal diaphragms and endocones