BACKGROUND Megaloolithid eggs have long been associated with sauropod dinosaurs. Despite their extensive and worldwide fossil record, interpretations of egg size and shape, clutch morphology, and incubation strategy vary. The Pinyes locality in the Upper Cretaceous Tremp Formation in the southern Pyrenees, Catalonia provides new information for addressing these issues. Nine horizons containing ...

Islands are viewed as natural evolutionary laboratories for terrestrial organisms because they have boundaries that limit dispersal and often reveal evolutionary patterns and mechanisms. One such pattern is that the smallest and largest species of different types of tetrapod animals are frequently found on islands. Here I describe two new diminutive species of snakes of the genus Leptotyphlops ...

Double-nesting behaviour, a rare breeding system in which females lay in two nests, one incubated by herself and the other one by her mate, could be considered an intermediate stage in the evolutionary trend from biparental to uniparental care of single clutches. We examined the occurrence and success of double-nesting behaviour in Red-legged Partridges Alectoris rufa in Central Spain. Clutch s...

To study clutch size related energetic costs of incubation, clutch sizes were experimentally manipulated and metabolic rate of female great tits Parus major (L.) during nocturnal incubation (MRinc) was measured with the use of mobile oxygen analysers. Each individual was repeatedly measured, while incubating either reduced, control or enlarged clutches. In contrast to most previous studies, the...

This study presents clutch size, egg-characteristics and within-clutch egg dimensions variation in Nuthatch Sitta europaea in deciduous forests (Hrvatsko zagorje area; NW Croatia). Study comprised the period from 2000 to 2002. Cluch size were 5–8 eggs (mean = 6.63, modal = 7 eggs). Egg length averaged 19,79 mm, egg breadth 14.42 mm, egg volume 2099.66 mm3 and egg shape index 1,37 (during tree y...

Field studies were conducted with "three species of passerine, in order to investigate the possibility that an energetic constraint limits reproduction during incubation. Swallows (Hirundo rustiea), Dippers (Cinelus einelus) and Great Tits (Parus nlajor) were studied at sites in Central Scotland. All three species exhibit gynelateral intermittent incubation, so time and energy must be allocated...

Several studies of eye morphology have analysed macroevolutionary patterns in the diversity of eyes, and although these studies are often linked to environment or behaviour, they provide only indirect evidence of selection. Specific data to show the microevolutionary potential for adaptation by natural selection in eye morphology have been lacking. We document directional selection on eye size,...

53 According to life-history theory, the development of immune function should be balanced, through evol54 utionary optimization of the allocation of resources to reproduction, and mechanisms that promote sur55 vival. We investigated interspecific variability in cell-mediated immune response (CMI), as measured by 56 the phytohaemagglutinin (PHA) assay, in relation to clutch size, longevity, and...