Bird Bones Research Articles

Excavation of four caves in the Geodha Smoo near Durness, Sutherland

In response to the threat posed by marine and river erosion, a series of deeply stratified midden deposits was excavated in caves leading off a narrow, rock-cut inlet known as the Geodha Smoo, near Durness, Sutherland. These included the famous Smoo Cave (NGR: NC 4136 6714), at the southern end of the inlet; two smaller caves cut into the western wall of the inlet (Glassknapper's Cave and Antler Cave); and a fourth cave (Wetweather Cave) in the eastern wall. The majority of excavated deposits from these caves appear to relate to Viking/Norse or post-Norse activity, with fish bones, marine shells and mammal and bird bones representing the processing and consumption of marine and terrestrial foods. Possible evidence for metalsmithing in the form of iron slag and boat nails could suggest that boats were repaired in the sheltered inlet. Four radiocarbon dates from Smoo Cave and Glassknapper's Cave provide evidence for use of these sites between the eighth and 11th centuries AD. Convincing evidence for pre-Norse activity, although unsupported by radiocarbon dates, was recovered from Glassknapper's Cave in the form of probable Iron Age pottery, while late Neolithic pottery came from floor deposits in the Wetweather Cave.

Torsional resistance as a principal component of the structural design of long bones: Comparative multivariate evidence in birds

Here we study the occurrence of torsion-resisting morphological and histological features (thin bone walls, circular shaft cross-section, oblique collagen fibers, and laminar tissue arrangement) in a sample of 168 long bones from wings and legs of 22 bird species. These structural parameters were measured in mid diaphyseal undemineralized cross-sections and analyzed using uni-, bi-, and multivariate (principal components analysis) data analysis techniques. We found that the four variables are significantly and positively correlated, and that covariation between variables accounts for as much as 58% of the total variation. These results suggest that torsion is a main determinant of the macro- and microstructural design of long bones in birds. Humerus, ulna, and femur generally possess torsion-resisting features, while other bones (radius, carpometacarpus, tibiotarsus, tarsometatarsus, and foot phalanx) rather show bending/axial load-resisting structural properties. These results are congruent with in vivo strain data from the literature, which reported high torsional loading in humerus and ulna during flapping flight, but also in the subhorizontal avian femur during terrestrial locomotion. The precise function of the laminar tissue spatial arrangement, the role of pneumatization, and the influence of flight mode are discussed.

Variation of the Outer Circumferential Layer in the Limb Bones of Birds

The core of the limb bone cortex of mammals and birds is made of rapidly deposited, fibro-lamellar bone tissue (also present in non-avian theropods), which is usually surrounded by an avascular outer circumferential layer (OCL) of slowly deposited parallel-fibered bone. We present the first comparative allometric study of the relative OCL thickness (expressed as a fraction of the diaphyseal radius) in modern birds. Body size explains 79% of the OCL variation in thickness, which is inversely correlated with size, that is, shows negative allometry (slope -0.799). This may explain the apparent absence of OCL in the ratites. Since the OCL is deposited at the end of growth, we propose that its relative thickness probably correlates with the amount of slow, residual growth, which our results suggest to be on the average larger in small birds.

Effects of Ovulatory and Egg Laying Cycle on Bone Mineral Density and Content of Live White Leghorns as Assessed by Dual-Energy X-Ray Absorptiometry

Dual-energy X-ray absorptiometry has been validated in our laboratory as a noninvasive tool to assess skeletal integrity in live birds. The first objective of the current study was to determine if there were detectable changes in bone mineral density (BMD) and bone mineral content (BMC) while an egg was being formed in the oviduct. Implications from this experiment would define the time of day scans should be conducted for future experiments. Densitometric scans were conducted on the tibia and humerus of live hens undergoing active egg formation when hens were 0, 5, 15, and 20 h postoviposition at 24, 30, and 40 wk of age. No detectable changes in either the BMD or BMC of the tibia and humerus were observed as the egg was being formed in the reproductive tract at any age measured. These results suggest that densitometric scans may be conducted on bones in live birds at any time during the day, irrespective of the stage of egg formation. The second objective was to monitor the change and degree of variation in skeletal integrity of live birds during the first cycle of egg laying. The humerus and tibia of White Leghorns were scanned repeatedly at 10-wk intervals from 15 to 65 wk of age. The BMD of the humerus increased from 15 to 65 wk of age, whereas the BMD and BMC of the tibia increased from 15 to 55 wk of age, resulting in a bone-by-age interaction (P < 0.001). The BMC of the humerus did not change from 15 to 55 wk of age but increased at 65 wk of age. Age-related increases in BMD and BMC may be due to the inability of dual energy X-ray absorptiometry to distinguish medullary from structural bone. The CV for BMD and BMC of egg-type chickens was greater than 10% after 25 wk of age, which suggested that bone densitometry could be used as an indicator tool in genetic selection with a potential for improving skeletal integrity of birds.

COMPARISON OF THE SUPPLEMENTAL EFFECTS OF ROXAZYME-G ENZYME IN PALM KERNEL MEAL AND BREWERS DRIED GRAIN BASED DIETS FED TO MALE TURKEY POULTS

The influence of exogenous enzymes on the utilization of agro-industrial by-products in poultry ration was assessed. Palm kernel cake (PKC) meal and Brewer's dried grain (BDG) based diets were supplemented with Roxazyme-G enzyme and subsequently fed to male turkey poults for 8 weeks. Diets 1 and 2 contained PKC, which supplied 2.4% fibre while BDG supplied 2.4% fibre in diets 3 and 4. Diets 2 and 4 were supplemented with 15g of Roxazyme-G enzyme, while Diets 1 and 3 were not, thus acting respectively as controls for Diets 2 and 4. Roxazyme-G significantly (P 0.05) in the percentage of calcium and phosphorus elements in the bones of the experimental birds. Data from the study also showed that the poults fed diet 1 significantly (P [Niger Agric. J. 34 (2003): 116-124]

Hans Bots and Rob Visser (eds), Correspondance, 1785–1787, de Petrus Camper (1722–1789) et son fils Adriaan Gilles Camper (1759–1820), LIAS Sources and Documents Relating to the Early Modern History of Ideas, vol. 28, Amsterdam and Utrecht, APA–Holland University Press, 2002, pp. 304, illus., €50.00 (paperback ISBN 90-302-1098-2, ISSN 0304-0003).

The Dutch scientist second only to Boerhaave in international renown in the middle years of the eighteenth century, Petrus (otherwise Peter) Camper was typical of his time in bringing a restless intellectual curiosity to bear on a wide range of different subjects. Primarily a comparative anatomist, he made significant contributions to surgery, obstetrics, and ophthalmology as well. He discovered air spaces in bird bones and studied the hearing of fish and the croaking of frogs, while his measurement of the facial angle and his introduction of Camper's line notably furthered the young discipline of physical anthropology. From pioneer dissections of then little-known mammals, including an elephant and whales, he was later to apply his expertise to the identification of fossil vertebrates. At the same time, Camper was untypical in the privilege he enjoyed from middle life in having the economic option of either continuing in a successful medical career as a university professor and consultant, or of retreating into rural seclusion and comfort to spend his days in private research and writing. It was an option he exercised in favour of the latter twice. He owed it to late marriage to a burgomaster's widow of great wealth, a change in circumstances for which he paid a price in role ambiguity and in a sense of public obligation as a landowner, which ultimately led to high office. He seems to have been temperamentally ill-suited to a political life and retired from it depressed and frustrated. During the two years, 1785–7, leading up to his nomination as President of the Council of State of the United Provinces, Camper conducted an extensive correspondence with his third son, Adriaan, then following his father in a political career and in enjoying a leisurely grand tour which included a lengthy residence in Paris. Two collections of these letters, seventy-one by the father and fifty-one by the son, have survived and are now in the university libraries of Amsterdam and Groningen. Most of them in French but a few in English, they document on a day-by-day basis Adriaan's attempt to interest Georges Buffon in publishing the anatomical discoveries made by his father in his dissections of monkeys and whales. Buffon, by then old and feeble, expressed great admiration of the drawing that had resulted but could not be pinned down to acting in accordance with the father's wishes. In the end the negotiations came to nothing, and another thirty years elapsed before Adriaan saw into print the work on whales (only), long after his father's death. One of the editors of the publication under review, Rob Visser of the University of Utrecht, published in 1985 an authoritative account of Camper's zoological work and was consequently well-placed to realize the value of this correspondence for historians of the life sciences. This value resides most particularly in the light the letters shed on Camper's ways of working and intellectual preoccupations, in how his dissections had led him to view zoology in a very different way from Buffon, despite their shared antipathy to Linnaean method, and in how research on fossils was creating altered perspectives that would serve to shape the emerging discipline of palaeontology. The production of the volume is excellent and the editorial annotation all that one could hope for.

Hunting, fishing and animal husbandry at The Farm Beneath The Sand, western Greenland

A large and generally well preserved sample of animal bones was excavated at "The Farm Beneath The Sand" (Gården under Sandet, GUS) in the Norse Western Settlement in Greenland. The sample represents the entire period of occupation, from ea. AD 1000-1400 and could be divided into three time phases, allowing analysis of changes in the economy of the farm. A total of 8,250 bone fragments, from at least 36 species of fish, birds and mammals, were identified. The 166 fish bones from GUS constitute the hitherto largest sample from a Norse site in Greenland. The generally poor state of preservation of the fish bones, in combination with the fact that fish bones were only found in sieved samples, indicate that fishing may have played a larger role than the sheer number of fish bones indicates. The majority of the fish bones are from Arctic char (Salvelinus alpinus), followed by cod (Gadus morhua) and capelin (Ma/lotus villosus). The material of bird bones is strongly dominated by ptarmigan (Lagopus mutus), but there are also bones of, e.g., geese, auks, whooper swan (Cygnus cygnus), mallard (Anas platyrhynchos) and eider (Somateria mollissima). Remains of wings of White-tailed eagle (Haliaeetus albicilla) and a goose were found. The GUS people exploited the wild mammal fauna but also kept domestic animals. Bones of seals numerically dominate the mammal bone material. Reindeer (Rangifer tarandus) was also important, and Arctic hare (Lepus arcticus) was a smaller but constant element. Second in numerical importance among the mammals is sheep+goat which strongly dominate among the domestic animals. Right from the first time phase, the number of goats (Capra hircus) almost equals that of sheep (Ovis aries). The find of a complete goat skeleton is of particular interest. Cattle (Bos taurus) was also kept at GUS, whereas the find of only a single bone of swine (Sus domesticus) does not prove pig husbandry. Measurements of metacarpal and metatarsal bones indicate that sheep, goats and cattle were small and stout. Age estimates based on, i.a., tooth eruption and wear patterns indicate that cattle were kept mainly to provide milk. For sheep and goats, a more mixed exploitation is indicated, however, with the main emphasis on meat production. There are several indications of temporal changes in the economy of GUS: The exploitation of seals increases, and while common seal (Phoca vitulina) dominates the first phases, there is a change towards dominance of harp seal (Phom groenlandirn) in the later phase. The exploitation of reindeer decreases, sheep and goat become slightly more numerous, and cattle becomes scarcer. GUS was an inland farm, and its overall economy seems to have been strongly based on exploitation of the inland fauna: hunting of ptarmigan, geese, reindeer and hare; seals brought in from nearby breeding grounds; fishing for char, maybe at the mouth of the river in the nearby fjord. Hunting and fishing was combined with animal husbandry dominated by sheep and goats, and with a little cattle. Excursions must have been made to the seacoast to obtain harp seals and walruses (Odoben11s rosmarus). Throughout the period of occupation the relation between bone fragments of wild and domestic mammals was ea. 1:1, whereas the animal food gradually became more dominated by marine species: in phase 1, 29% of the fragments are from marine species, versus 44% in phase 3. A fair number of bones from horses and a skull and mandibles from greyhound-type dogs indicate that the farm had a certain level of status.

Fragmentation and preservation of bird bones in uneaten food remains of the Gyrfalcon Falco rusticolus

This paper presents fragmentation patterns of bird bones in uneaten food remains of the gyrfalcon Falco rusticolus. The victims' bones show a relatively low degree of fragmentation. Elements of the pectoral girdle and wing predominate while head and leg elements are poorly represented.

Lead and arsenic in bones of birds of prey from Spain

The bones (humerus and/or femur) of 229 birds of prey from 11 species were analyzed for Pb and As to evaluate their exposure to Pb shot. The species with the highest mean Pb levels were red kite ( Milvus milvus) and Eurasian griffon ( Gyps fulvus), and the species with the lowest levels were Eurasian buzzard ( Buteo buteo) and booted eagle ( Hieraaetus pennatus). Red kite also had the highest mean As level, an element present in small amounts in Pb shot. Elevated bone Pb concentrations (>10 μg/g dry weight) were found in 10 birds from six species. Clinical signs compatible with lethal Pb poisoning and/or excessive bone Pb concentrations (>20 μg/g) were observed in one Eurasian eagle-owl ( Bubo bubo), one red kite, and one Eurasian griffon. Pb poisoning has been diagnosed in eight upland raptor species in Spain to date.

THE DIET OF THE BARN OWL TYTO ALBA IN THE NEGEV DESERT

Food remains left by predators, and pellets in particular, are a good source of information about species composition in a particular area. Such information is essential for research and conservation purposes. We report here on the composition of an assemblage of barn owl (Tyto alba) pellets collected from the Holot Agur Nature Reserve located in the sand dunes in the northwestern Negev, about 10 km north of Nizzana, at 30o58′N 34o24′E. Most of the material was in compacted form, with some in the form of whole pellets. The remains were collected on 18 November 2002 from an old bus that had been abandoned in the area years before. The climate of this area is arid, with an average annual rainfall of about 100 mm, concentrated mainly between December and February (Jaffe, 1988). In the northern Negev the average mean monthly ambient temperature ranges between 11 oC in January and 26 oC in July (Jaffe, 1988). The bus was located in sand dunes where the plant community is composed mainly of low bushes of Arthemisia monosperma and Retema roetam. The area within a radius of about 1 km from the bus is devoid of trees, caves, or other potential nesting or roosting sites suitable for barn owls. Judging by the amount of material and eggshells, the bus has apparently been used for several years by barn owls. The material was brought to the lab in Tel Aviv where it was soaked for 24 hours in water, after which the bones and exoskeletons of invertebrates were separated from vegetational material and hair. Skulls and mandibles were identified using the reference collection of the Zoological Museum of Tel Aviv University. The minimum number of individuals (MNI) per species was calculated from mandibles or crania. The assemblage was composed mostly of small mammals (97%), some reptiles, and a few bones of birds in addition to some invertebrates (Table 1). It contained the remains of at least 1026 specimens, 989 of which were mammals belonging to 10 species of rodents—seven of the family Gerbillidae, two species of shrews (the common shrew and the pygmy white-toothed shrew), and an insectivorous bat. In addition, there were chameleons, geckos, and Agama lizards. The most abundant species were gerbils— Gerbillus allenbyi, G. pyramidum, and G. gerbillus (some of which may belong to G. dasyurus, whose mandibles are indistinguishable from those of G. gerbillus)—followed by the common shrew Crocidura suaveolens and the jirds Meriones crassus and M. sacramenti. All species found were known to occur in or near the area (Yom-Tov, 1988; Werner, 1988; Mendelssohn and Yom-Tov, 1999; Yom-Tov and Dayan, 1996). NOTE:

HAWAIIAN BIRDS: LESSONS FROM A REDISCOVERED AVIFAUNA

IN THE INTRODUCTION to Hawaiian Birdlife, Andrew Berger (1972) wrote with frustration and dismay about his futile search for several species of endemic Hawaiian birds that had been described by collectors in the 1890s, but apparently were extinct by the mid-20th century. He bemoaned the fact that the ecology and behavior of those birds could never be studied. In fact, the loss of diversity and the gaps in our knowledge of the ecology and evolution of Hawaii's birds both are far greater than Berger could have imagined. During the past three decades, paleontological efforts spearheaded by Storrs Olson and Helen James have unearthed an unsuspected number and diversity of extinct birds. Bones collected from sand dunes, lava tubes, sinkholes, and former lakebeds have approximately doubled the number of endemic Hawaiian species. Among the fossil taxa collected and described by Olson and James are at least 15 new species in the spectacular honeycreeper radiation (tribe Drepanidini); several species of raptors unknown in the historical avifauna, including an eagle, a harrier, and a radiation of bird-eating owls; and many flightless birds, including rails, ibises, ducks, and geese (Olson and James 1982a, b, 1991; James and Olson 1991). Olson and James have demonstrated that the historically recorded Hawaiian avifauna, although spectacular, is a meager and biased sample of the fauna that existed prehistorically (i.e. before 1778, the year of the arrival of James Cook in the Hawaiian Islands). Radiocarbon dating of bones of extinct birds and presence of extinct birds in some archaeological sites have shown that extinctions on Hawaii occurred after humans colonized the archipelago, -1,600 years ago (Olson and James 1982a, b; James et al. 1987, Burney et al. 2001). That pattern of massive, rapid extinction of endemic birds following human colonization has been found on oceanic islands throughout the

On the Chemical Purity of Marine Microfossils

As a paleontologist, I was pleased to see the 35-million-year-old shell of the planktonic foraminiferan Cribrohantkenina inflata grace the cover of Physics Today ( Physics Today 0031-9228 54 12 2001 16 https://doi.org/10.1063/1.1445530. December 2001; story on page 16 ). Calcium carbonate–secreting microfossils are a powerful proxy for estimating sea-surface temperature change through time using stable oxygen isotopes. Another challenge that biogeochemists and geoscientists face is the alteration of in vivo isotopic values by mineral and chemical changes after an organism’s death. Implicit in any isotopic analysis using calcite shells, or fossil mammal teeth, or even dinosaur bones, is the assumption that the original stable isotopes survived the passage of millions of years.A hemisphere away from the late Cretaceous marine localities of Paul Pearson’s work, 1 1. P. Pearson, et al. , Nature 413, 481 (2001). https://doi.org/10.1038/35097000 dinosaur bones lie buried in late Cretaceous clays above the Arctic Circle on the North Slope of Alaska. 2 2. W. A. Clemens, L. G. Nelms, Geology 21, 503 (1993). https://doi.org/10.1130/0091-7613(1993)021<0503:PIOATV>2.3.CO;2 They are so well preserved that an oil geologist in the 1960s originally identified them as the fossil remains of Ice Age mammals. A collection of those bones is cataloged in the University of California Museum of Paleontology. Under high magnification, the Alaska fossils reveal a beautifully preserved system of bone cells that are identical to the micron-scale architecture of a modern vertebrate bone. Similar to the Pearson group’s foraminifera, the dinosaur bones are entombed in clay sediments and do not appear altered by secondary remineralization or recrystallization. Microbeam particle-induced x-ray emission analysis revealed, however, that the bones showed significant postmortem enrichment by metals, primarily iron and manganese, more than 104 times greater than in the bones of modern crocodilians and birds (a dinosaur’s closest living relatives). 3 3. M. B. Goodwin, G. S. Bench, J. Vertebr. Paleontol. 20(3), 45A (2000). Clay surrounding the Alaska dinosaurs was also markedly enriched in these metals from the burial environment.Understandably, such factors are site specific and most likely vary by sediment layer and location. Their range and potential influence on a paleobiological isotopic signature remains largely unknown. Until that situation changes, the potential alteration of stable isotope values in fossil shells, bones, and teeth prevents the rejection of the null hypothesis that all fossil material is altered.Beauty is in the eye of the beholder, and exceptional fossil preservation, even at the micron level, does not guarantee pristine chemistry.REFERENCESSection:ChooseTop of pageREFERENCES <<CITING ARTICLES1. P. Pearson, et al. , Nature 413, 481 (2001). https://doi.org/10.1038/35097000 , Google ScholarCrossref2. W. A. Clemens, L. G. Nelms, Geology 21, 503 (1993). https://doi.org/10.1130/0091-7613(1993)021<0503:PIOATV>2.3.CO;2 , Google ScholarCrossref3. M. B. Goodwin, G. S. Bench, J. Vertebr. Paleontol. 20(3), 45A (2000). Google Scholar© 2002 American Institute of Physics.

Avifaunal extinctions, vegetation change, and Polynesian impacts in prehistoric Hawai'i

AbstractPre‐contact avifaunal extinctions in Hawai'i generally have been attributed to human predation and/or landscape alteration by colonizing Polynesians. However, until recently there have been insufficient data for evaluating most of the important variables involved in this issue. This situation has changed with recent archaeological, paleontological, and wetland coring research conducted on O'ahu's ‘Ewa Plain, a hot, dry emerged limestone reef characterized by numerous sinkholes. The main evidence obtained from this research includes (1) wetland coring data that stratigraphically demonstrate forest decline before any burning, (2) radiocarbon dating of bones of rats and extinct birds that provides a time frame for their occurrence unavailable from stratified deposits, and (3) the radiocarbon‐based history of human settlement of the 'Ewa Plain.Based on this evidence the argument is made that (1) at least some major avian extinctions occurred within the period immediately following Polynesian colonization, (2) these extinctions were due primarily to the rapid decline of their native lowland forest habitat, (3) human settlement of the 'Ewa Plain occurred after native forest collapse, not coincident with it, and (4) the main source of destruction of the native forests was the introduced Polynesian rat, Rattus exulans, not Hawaiian agricultural clearing and burning. This model also explains the absence of large quantities of bird bone in early sites (in contrast to other places in Polynesia and Micronesia), and the absence in early middens of many plants (notably Kanaloa kahoolawensis) that were common in the native forest.

Prehistoric Butchery and Consumption of Birds in the Kingdom of Tonga, South Pacific

We evaluate the preservational attributes (element frequency, breakage, burning, cut-marks, rodent gnawing, and age) of ca.500 bird bones from three prehistoric archaeological sites on the Polynesian islands of Foa and Lifuka in the Ha‘apai Group, Kingdom of Tonga. Two of the sites lie in calcareous beach sands whereas the third is the refuse infilling of a well. Although differing in age, all three sites are unequivocally cultural in origin, as evidenced by rich artifact assemblages and various sedimentological features (pits, hearths, etc.) that reflect human activities. The sites also contain bones from a diverse assemblage of marine fish, marine and terrestrial reptiles (sea turtles, iguanas), and terrestrial mammals (fruit bats, rats, pigs, dogs). We find no evidence for deposition of bones (bird or otherwise) in these Tongan sites by non-human agents. This is expected given that we are unaware of any non-human species or geological process that would concentrate the bones of fishes, reptiles, birds, and mammals on a beach ridge or in a well in Tonga. This is especially the case since the species range from very small to very large, and represent marine, fresh water, coastal, and forested habitats. Nevertheless, clear evidence of cultural involvement cannot be discerned on most individual bones, whether bird or non-bird. Furthermore, most taphonomic attributes (element frequency, breakage, burning, and cut-marks) of bones of a domesticated species (the chicken, Gallus gallus) resemble those found on bones of indigenous landbirds. We believe that all bones in any zooarchaeological assemblage should be evaluated carefully to determine who or what was responsible for their deposition. We see no reason, however, why bird bones should be held to some standard higher than those applied to the bones of other taxa, as some have suggested.

Human exploitation of seabirds in coastal southern Chile during the mid-Holocene

We analyzed a collection of 738 bird bones, representing a minimum of 71 individuals, found in a settlement of hunter-gatherers from the mid-Holocene, 5,000 years BP, in the coastal locality of Chan Chan, southern Chile. The camp was inhabited for over ca. 500 years, during which time a steady hunting pressure on the local marine resources was exerted, particularly on seabirds. The most abundant taxon (bones/number of individuals) was the red-legged cormorant Phalacrocorax gaimardi (551/44) which was also the prey which provided the highest edible proportion of body mass. Albatrosses Thalassarche cf. melanophris (103/12) and shearwaters Puffinus cf. griseus (20/5) were secondary prey. Cormorants were presumably hunted at their breeding colonies (which are still present in the area) so it is probable that egging also occurred. Because they are pelagic, albatrosses could have been hunted at sea, but the adequate technology for this (boats, hooks) is not apparent in the archaeological record. The bird assemblage obtained in the sample does not qualitatively differ from that of the present, indicating a reasonable stability in species richness from the considered period until the present. The high diversity of coastal resources in Chan Chan was likely important in leading to the, at least seasonal, occupation of these areas by hunter-gatherers and also may have encouraged the development of the adequate technology for the exploitation of these resources.

Avian long bones, flight and bipedalism

Morphological, geometrical, chemical and mechanical characteristics of avian long bones are reviewed. Important differences exist between long bones of birds and mammals. Differences are also present in appendicular bones of birds, either between wing bones and leg bones or proximal (stylopodial) long bones and distal (zeugopodial) long bones. Special emphasis is put on pneumatization, in terms of both phylogenetic origin and geometrical and mechanical characteristics linked to it. Cortical thickness, bending strength and flexural Young's modulus were significantly lower in pneumatized bones than in marrow-filled bones. Possible adaptive reasons for the differences shown are discussed.

Incidence and mechanical significance of pneumatization in the long bones of birds

The incidence of pneumatization in avian long bones was studied, by direct observation, in a large sample of species. Only proximal bones (humerus and femur) presented pneumatization in the sample studied. The incidence obtained was related to the variation of the maximum cortical thickness and mechanical properties, such as bending strength and flexural Young's modulus. Cortical thickness, bending strength and flexural Young's modulus were significantly lower in pneumatized bones than in marrow-filled bones. Furthermore, some congruence was found between pneumatization and systematic groups when compared. In this sense, Charadriformes was the only order studied with total absence of long bone pneumatization. Results on cortical thickness appear to be in agreement with modelling predictions previously made and with results obtained on other groups of flying vertebrates. The possible selective advantage of reduction in cortical thickness in relation to flying is suggested.

Incidence and mechanical significance of pneumatization in the long bones of birds

The incidence of pneumatization in avian long bones was studied, by direct observation, in a large sample of species. Only proximal bones (humerus and femur) presented pneumatization in the sample studied. The incidence obtained was related to the variation of the maximum cortical thickness and mechanical properties, such as bending strength and flexural Young's modulus. Cortical thickness, bending strength and flexural Young's modulus were significantly lower in pneumatized bones than in marrow-filled bones. Furthermore, some congruence was found between pneumatization and systematic groups when compared. In this sense, Charadriformes was the only order studied with total absence of long bone pneumatization. Results on cortical thickness appear to be in agreement with modelling predictions previously made and with results obtained on other groups of flying vertebrates. The possible selective advantage of reduction in cortical thickness in relation to flying is suggested.

Fine structure of bone in dinosaurs, birds and mammals.

After observation of detailed structural evidence for the origin of birds from dinosaurs, and in light of evidence that dinosaur bone tissue resembles the histology in mammals, the histology of bone has become one of the focal points in discussions of the physiology of dinosaurs and Mesozoic birds. Most of this microstructural information has focused on features related to the vascular organization and the amount of remodelled bone around vascular canals. However, the finer structures have received less attention, although differences in such structures have been observed among modern vertebrates. Here we present evidence that canaliculi--the submicrometre-sized channels that interconnect bone cells and vascular canals--and the collagen fibre bundles in bone are differently organized among certain dinosaur lineages. Ornithomimid dinosaurs are more like birds than mammals in these features. In canalicular structure, and to some extent in fibre bundle arrangement, ornithischian dinosaurs are more like mammals. These differences in both canalicular and lamellar structure are probably linked to differences in the process and rate of bone formation.

NEW SPECIES AND RECORDS OF BIRDS FROM PREHISTORIC SITES ON NIUE, SOUTHWEST PACIFIC

We report the first prehistoric bird bones from the isolated limestone island of Niue, South Pacific. Discovered in a cave known as Anakuli, the bones are Holocene in age but lack cultural association. They represent three extinct species: a night-heron (Nycticorax kalavikai), a new species known thus far only from Niue but closely related to an extinct undescribed species from Tonga; the “Niuafo'ou” Megapode (Megapodius pritchardii), known historically only from Niuafo'ou (Tonga) but recorded from prehistoric sites elsewhere in Tonga; and Gallirallus huiatua, a new species of flightless rail presumably endemic to Niue and distinct from extinct, flightless congeneric species from island groups immediately east (Cook Islands) and west (Tonga) of Niue. The first two species are in accord with the overall biogeographic affinity of the extant avifauna of Niue, which is West Polynesian rather than East Polynesian.