Gastrolite
Gastroliths ( ancient Greek γαστήρ gaster 'belly', 'stomach' and λίθος lithos 'stone') or stomach stones are hard objects in the digestive tract of animals . In a narrower sense, gastroliths refer to stones that have been swallowed by vertebrates and are or were in the stomach . Animals that ingest stones are also known as lithophages ("stone eaters").
Among animals living today, the behavior of swallowing stones ( lithophagy ) is known, especially of birds , crocodiles and seals . One knows fossils of dinosaurs like the sauropods or other reptiles like the Tangasauriden from the Permian , fossil crocodiles and plesiosaurs , in which stomach stones are found in the stomach area of the skeleton.
The function of the stones is so far only herbivorous fully understood (herbivorous) birds. With them, the swallowed stones, which are also known as "grit" or "woad grains", are used in the gizzard (ventriculus) to crush the food. The stone capercaillie, for example, is absolutely dependent on gastroliths and even dune young take them up. In the winter months, the stone capercaillie feeds mainly on the buds of the larch's end shoots. These end shoots have a thick layer of bark and cambium . During the primary processing of these end shoots in the stomach, these layers are rubbed off with the help of the gastroliths, so that only the pith of the stalk with a thickness of about one millimeter remains of the three to five millimeter thick buds. In the case of ( aquatic ) animals living in water that do not have a very muscular stomach, it is discussed whether stomach stones could also serve as ballast . Or maybe most of the stones were accidentally swallowed with food.
"Gastroliths" are also the calcareous mineral crusts or concretions formed inside crustaceans , so-called crab eyes, which serve as intermediate storage for the minerals required during molting .
In veterinary medicine , the term pathological, i.e. pathological concretions, which have arisen from food residues and gastric juices in the stomach of herbivorous mammals . These objects are also called bezoars .
literature
- Oliver Wings: Identification, distribution and function of gastroliths in dinosaurs and living birds with a focus on ostriches (Struthio camelus) . Dissertation, University of Bonn
- Oliver Wings: A review of gastrolith function with implications for fossil vertebrates and a revised classification. In: Acta Palaeontologica Polonica , 52 (1), 2007, pp. 1-16. app.pan.pl ( Memento of March 7, 2008 in the Internet Archive ) (PDF)
- Oliver Wings, PM Sander: No gastric mill in sauropod dinosaurs: new evidence from analysis of gastrolith mass and function in ostriches . In: Proceedings of the Royal Society B: Biological Sciences , v. 274 (1610), 2007, pp. 635-640. doi: 10.1098 / rspb.2006.3763
Web links
Individual evidence
- ↑ RL Potapov, VE Fling (ed.): Handbook of the birds of the Soviet Union. Volume 4: Galliformes, Gruiformes. Aula Verlag, Wiesbaden 1989, ISBN 3-89104-417-8 , p. 150
- ↑ RL Potapov, VE Fling (ed.): Handbook of the birds of the Soviet Union. Volume 4: Galliformes, Gruiformes. Aula Verlag, Wiesbaden 1989, ISBN 3-89104-417-8 , p. 149