Digestion and the Digestive System

Ziswiler, Vinzenz; Farner, Donald S.

doi:10.1016/b978-0-12-249402-4.50015-2

Cited by 158 publications

(108 citation statements)

References 244 publications

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“…While a stone in a gizzard is subject to strongly fluctuating forces from defined directions [direct and lateral compression created by regular contraction pattern of two pairs of muscles (Duke 1986b;Ziswiler & Farner 1972)], a stone in a rock tumbler is in constant movement, by uplift in the grooves of the rubber-lined drum and a short fall once the position in the groove becomes unstable. The total forces in the tumbler are thus probably much weaker and more equally distributed than in a gizzard.…”

Section: Discussionmentioning

confidence: 99%

“…Gastroliths of these German farm ostriches were used for comparison (Wings 2004;Wings & Sander 2007). To facilitate and accelerate possible chemical effects on the gastroliths, hydrochloric acid (HCl) and pepsin significantly higher in concentration than in gastric juices of birds (Duke 1986a;Ziswiler & Farner 1972) were used for the simulated stomach juices. Freshly secreted gastric juice contains about 0.5 % HCl and has a pH around 2 (Duke 1986a;Schmidt-Nielsen 1997), but the normal pH in the stomach is slightly higher due to dilution by ingesta (Duke 1986a).…”

Section: Methodsmentioning

confidence: 99%

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A simulated bird gastric mill and its implications for fossil gastrolith authenticity

Wings

2009

Foss. Rec.

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A rock tumbler, stones, water, plant material, hydrochloric acid, and pepsin were used to simulate a bird gizzard in order to study abrasion rate and influence of stomach juices and foodstuff on gastrolith surface development. The experiment lasted for six months. Each week, the "stomach" was supplied with fresh grass and stomach juices. After the end of the experiment, the set of stones had a combined weight loss of 22.4%, with softer rock types showing higher abrasion rates. The combination of stomach juices and silica phytoliths within the grass had no visible effect on stone surface development: polish or pitting did not occur. A second experiment combined only pebbles with water in the tumbler. Results indicate that rock abrasion is mainly caused by contacts between moving stones. A comparison with authentic ostrich gastroliths showed that abrasion in the artificial stomach must have been lower than in a real gizzard, but still too high to maintain or develop surface polish. If high polish occasionally seen on sauropodomorph dinosaur gastroliths was indeed caused in a stomach environment, it implies digestive processes different from those of extant birds and the "artificial gizzard". Geologic origins of polish, such as transport in hyperconcentrated flows, wind blasting, or tectonic movements must be considered for polished fossil gastroliths and isolated clasts in fine-grained sediments (exoliths). <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.200800013" target="_blank">10.1002/mmng.200800013</a>

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

A simulated bird gastric mill and its implications for fossil gastrolith authenticity

Wings

2009

Foss. Rec.

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“…It is already clear that the role of the integrative segment depends on the osmotic and metabolic state of the bird, and that there are interspecific and intergroup differences (Skadhauge 1981, Thomas 1982. The vast morphological differences among the organs involved (for reviews, see Ziswiler andFarner 1972, Johnson 1979) emphasize the importance of many more quantitive, comparative-physiological studies.…”

Section: Osmoregulation Ionoregulation and Nitrogen Excretionmentioning

confidence: 99%

Some Recent Advances in Avian Physiology

Farner

1983

Journal of the Yamashina Institute for Ornithology

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With primary attention to feral species, some important, recent trends in avian physiology have been selected and briefly described. Included are investigations of the exchanges of gases between embryo and external environment during incubation; structure and function of the lung-airsac system; avian energetics; control and energetic cost of molt; osmoregulation, ionoregulation and nitrogen excretion, including roles of kidney, lower gut, salt glands, and renin-angiotensin system; endocrinology; and orientation and navigation. Among these trends there has been an increase in the spectrum of species investigated, greater effort to make measurements under natural conditions and successes with experiments on feral species in the field. Physiological investigations have been facilitated by the great fund of information on the natural history and zoogeography of birds.

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“…Gastrolites are important components of avian consumption because they substantially contribute to grinding foods in the bird gizzard (Ziswiler & Farner 1972, Beaune et al 2009) and, to a lesser extent, as a possible source of necessary minerals (Gionfrido & Best 1996, Lee et al 2004. Granivorous birds have been indicated as the main guild requiring gastrolites in their diets and, unsurprisingly, they have received much more attention than other guilds as insectivores (Gionfrido & Best 1995, Lopez-Calleja et al 2000.…”

Section: Introductionmentioning

confidence: 99%

Allochthonous and autochthonous components from gizzard grit of Theristicus melanopis in anthropogenic pastures of southern chile

et al. 2013

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Allochthonous and autochthonous components from gizzard grit of ABSTRACTNumerous vertebrates, and in particular birds, ingest stones (geo-gastrolites) to favour the breakdown and digestion of food in the muscular stomachs. Between 1993 and 1994 we evaluated the quantity, relative abundance and quality of autochthonous (geo-gastrolites) and allochthonous (pieces of glass) components of the grit in gizzards of black-faced ibis (Theristicus melanopis) inhabiting the pastures of southern Chile. Grit elements were present in 32 out of 48 (66,7%) of all gizzard analysed. A total of 572 particles were recorded from which, 69.1% corresponded to autochthonous elements and 27.8% were allochthonous particles. Both components are similar in shape; however glass contributes considerably more in terms of mass. Gender differences reveal that females consume a signifi cantly greater number of allochthonous elements than males. We postulate the hypothesis that, due to their high energy requirements, females ingest more pieces of glass to facilitate the breakdown and digestion of food with a limited nutritional value, thus increasing their reproductive success. KEYWORDS:Black-faced ibis, glasses, gastrolites, pastures, south Chile RESUMENNumerosos vertebrados y en particular las aves, ingieren piedras (gastrolitos) para favorecer la maceración y la digestión del alimento en los estómagos musculares. Entre 1993 y 1994 evaluamos la cantidad, abundancia relativa y calidad de componentes autóctonos (piedras) y alóctonos (trozos de vidrios) de los gastrolitos presentes en las mollejas de bandurrias (Theristicus melanopis) en praderas agrícolas del sur de Chile. Los gastrolitos se presentaron en 32 de las 48 (66,7%) mollejas analizadas. Se registró un total de 572 partículas de las cuales 69,1% fueron elementos autóctonos y 27,8% partículas alóctonas. Ambos componentes no difi rieren en la forma pero los vidrios aportaron signifi cativamente mayor masa. Las hembras consumieron un número signifi cativamente mayor de elementos alóctonos que los machos. Postulamos la hipótesis que las hembras, con alto requerimiento energético, ingieren más trozos de vidrio para incrementar la efi ciencia de maceración y digestión de alimentos con reducido valor nutricional, lo que les permitiría incrementar su éxito reproductivo.

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Digestion and the Digestive System

Cited by 158 publications

References 244 publications

A simulated bird gastric mill and its implications for fossil gastrolith authenticity

A simulated bird gastric mill and its implications for fossil gastrolith authenticity

Some Recent Advances in Avian Physiology

Allochthonous and autochthonous components from gizzard grit of Theristicus melanopis in anthropogenic pastures of southern chile

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