"and that this was a feature they shared with birds. In 2007 Oliver Wings reviewed references to gastroliths in scientific literature and found considerable confusion, starting with the lack of an agreed and objective definition of ""gastrolith"". He found that swallowed hard stones or grit can assist digestion in birds that mainly feed on grain but may not be essential—and that birds that eat insects in summer and grain in winter usually get rid of the stones and grit in summer. Gastroliths have often been described as important for sauropod dinosaurs, whose diet of vegetation required very thorough digestion, but"
"teeth of mammals, many species swallow rocks and pebbles (so called gastroliths) to aid in digestion: The rocks are washed around in the stomach, helping to grind up plant matter. Fossil gastroliths have been found associated with both ornithopods and sauropods, though whether they actually functioned as a gastric mill in the latter is disputed. Salt water crocodiles also use gastroliths as ballast, stabilizing them in the water or helping them to dive. A dual function as both stabilizing ballast and digestion aid has been suggested for gastroliths found in plesiosaurs. The reptilian nervous system contains the same basic part"
"was required to feed the young dinosaur, possibly the adult dinosaur regurgitated food into the young dinosaur's mouth (""see"" altricial). This behaviour is seen in numerous bird species; parent birds regurgitate food into the hatchling's mouth. Both birds and dinosaurs use gizzard stones. These stones are swallowed by animals to aid digestion and break down food and hard fibres once they enter the stomach. When found in association with fossils, gizzard stones are called gastroliths. Gizzard stones are also found in some fish (mullets, mud shad, and the gillaroo, a type of trout) and in crocodiles. On several occasions, the"
"interpreted them as gastroliths. In 1934, the Howe Quarry, a fossil location in northwestern Wyoming also yielded dinosaur bones with their associated gastroliths. In 1942, William Lee Stokes recognized the presence of gastroliths in the remains of sauropod dinosaurs recovered from Late Jurassic strata. Geologists usually require several pieces of evidence before they will accept that a rock was used by a dinosaur to aid its digestion. First, the stone must be unlike the rock found in its geological vicinity. Secondly, it should be rounded and polished, because inside a dinosaur's gizzard any genuine gastrolith would have been acted upon"
"coarser, and less numerous than most gastroliths, and were unlikely to have been used for the same purpose as those swallowed by herbivores. Instead, it has been suggested that they were swallowed to help clean the digestive tract, a usage which has been reported in living birds of prey as well as other carnivorous animals with high-fat diets, such as pinnipeds. The description of this specimen claimed that it was plausible, but uncertain, that ""Bohaiornis"" was ecologically similar to birds of prey. However, these rocks were later found to be mineral concretions, probably formed from the same mineral as the"
"found with sauropod skeletons were gastroliths. Gastroliths are stones intentionally swallowed to aid with digestion (as is seen in a variety of modern birds). However, more recent taphonomic and sedimentological evidence suggests that sauropods did not use stones for digestion due to the general rarity of finding gastric mill-like stones with sauropod remains, and low relative mass of the stones to the size of sauropod bodies. When gastrolith-like rocks are found with sauropods, it may be that they were accidentally ingested, or intentionally ingested for mineral uptake. Macronaria is nested within Neosauropoda and is sister to Diplodocoidea. These groups split"
"Gastrolith A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In other species the rocks are ingested and pass through the digestive system and are frequently replaced. The grain size depends upon the size of the animal and the gastrolith's role in digestion. Other species use gastroliths as ballast. Particles ranging in size from sand to cobble have been documented. Gastrolith comes from the Greek γαστήρ (""gastēr""), meaning ""stomach"", and"
"the dinosaurs once included have since been moved elsewhere, and the group is not used in most current taxonomies. Fossils of ""Anchisaurus"" were originally discovered in the Portland Formation of the Newark Supergroup in the Connecticut River Valley. This formation preserves an arid environment with strong wet and dry seasons, from the Hettangian age into the Sinemurian age, between about 200 and 195 million years ago. Digesting plant matter is a much more intensive biochemical process than digesting meat. This herbivore swallowed gastroliths (gizzard stones) to help break down the food in its stomach. Herbivorous dinosaurs needed a huge gut."
"λίθος (""lithos""), meaning ""stone"". Among living vertebrates, gastroliths are common among crocodiles, alligators, herbivorous birds, seals and sea lions. Domestic fowl require access to ""grit"". Stones swallowed by ostriches can exceed a length of . Amphibians such as the Axolotl are also known to deliberately ingest rocks that are presumed to be gastroliths. Apparent microgastroliths have also been found in frog tadpoles. Ingestion of silt and gravel by tadpoles of various anuran (frog) species has been observed to improve buoyancy control. Some extinct animals such as sauropod dinosaurs appear to have used stones to grind tough plant matter. A rare"
"carcasses of deceased plesiosaurimorphs. The shredding teeth of lamniform sharks indicates that perhaps they were scavengers or detrivores and that they only fed upon dead plesiosaurs. ""Muraenosaurs"" was an important piece of the ecosystem both as a carnivore and as a source of food to other species. Gastroliths have been a common find among the stomach contents of extinct marine reptiles. Their occurrence has led to two main hypotheses regarding the significance of the rocks. The first proposed usage, as described above, was to crush hard shelled food engulfed by the animal. The second hypothesis is that gastroliths were swallowed"
"dinosaurs, which left gastroliths as trace fossils. The partially digested and pulverized gizzard contents, now called a bolus, are passed into the intestine, where pancreatic and intestinal enzymes complete the digestion of the digestible food. The digestion products are then absorbed through the intestinal mucosa into the blood. The intestine ends via the large intestine in the vent or cloaca which serves as the common exit for renal and intestinal excrements as well as for the laying of eggs. However, unlike mammals, many birds do not excrete the bulky portions (roughage) of their undigested food (e.g. feathers, fur, bone fragments,"
"as part of a ball-mill system. Paleontologists are researching new methods of identifying gastroliths that have been found disassociated from animal remains, because of the important information they can provide. If the validity of such gastroliths can be verified, it may be possible to trace gastrolithic rocks back to their original sources. This may provide important information on how dinosaurs migrated. Because the number of suspected gastroliths is large, they could provide significant new insights into the lives and behaviour of dinosaurs. Gastrolith A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal"
"portrayal of hadrosaurs in ""Jurassic Park"", the 1990 science fiction novel by Michael Crichton. Hadrosaur diet Hadrosaurids, also commonly referred to as duck-billed dinosaurs or hadrosaurs, were large terrestrial herbivores. The diet of hadrosaurid dinosaurs remains a subject of debate among paleontologists, especially regarding whether hadrosaurids were grazers who fed on vegetation close to the ground, or browsers who ate higher-growing leaves and twigs. Preserved stomach content findings have indicated they may have been browsers, whereas other studies into jaw movements indicate they may have been grazers. The mouth of a hadrosaur had hundreds of tiny teeth packed into dental"
"Hadrosaur diet Hadrosaurids, also commonly referred to as duck-billed dinosaurs or hadrosaurs, were large terrestrial herbivores. The diet of hadrosaurid dinosaurs remains a subject of debate among paleontologists, especially regarding whether hadrosaurids were grazers who fed on vegetation close to the ground, or browsers who ate higher-growing leaves and twigs. Preserved stomach content findings have indicated they may have been browsers, whereas other studies into jaw movements indicate they may have been grazers. The mouth of a hadrosaur had hundreds of tiny teeth packed into dental batteries. These teeth were continually replaced with new teeth. Hadrosaur beaks were used to"
"seeds are still indeterminate. The intact nature of the sarcotesta in the largest seeds suggests that ""Isaberrysaura"" swallowed the seeds whole without chewing and that they were in the first stages of digestion based on their position in the gut. Based on its teeth, it is possible that the dinosaur had an omnivorous diet, but as no trace of animal remains have been found alongside the seeds, this remains speculative at best. It also remains possible that there were enzyme-producing bacteria present in the dinosaur's gut to aid in digesting tougher plant material as seeds. Isaberrysaura Isaberrysaura is a genus"
"were more terrestrial than others. Psittacosaurs had self-sharpening teeth that would have been useful for cropping and slicing tough plant material. Unlike later ceratopsians, they did not have teeth suitable for grinding or chewing their food. Instead, they used gastroliths—stones swallowed to wear down food as it passed through the digestive system. Sometimes numbering more than fifty, these stones are occasionally found in the abdominal cavities of psittacosaurs, and may have been stored in a gizzard, as in modern birds. Unlike many other dinosaurs, psittacosaurs had akinetic skulls: that is to say, the upper and lower jaws each behaved as"
"at digestion than small animals, because food spends more time in their digestive systems. This also permits them to subsist on food with lower nutritive value than smaller animals. Sauropod remains are mostly found in rock formations interpreted as dry or seasonally dry, and the ability to eat large quantities of low-nutrient browse would have been advantageous in such environments. Scientists will probably never be certain of the largest and smallest dinosaurs to have ever existed. This is because only a tiny percentage of animals ever fossilize, and most of these remain buried in the earth. Few of the specimens"
"Paleolithic diet The Paleolithic diet, Paleo diet, caveman diet, or stone-age diet is a modern fad diet requiring the sole or predominant consumption of foods presumed to have been the only foods available to or consumed by humans during the Paleolithic era. The digestive abilities of anatomically modern humans, however, are different from those of Paleolithic humans, which undermines the diet's core premise. During the 2.6-million-year-long Paleolithic era, the highly variable climate and worldwide spread of human populations meant that humans were, by necessity, nutritionally adaptable. Supporters of the diet mistakenly presuppose that human digestion has remained essentially unchanged over"
"from predation, reduction of energy use, and longevity, but it may be that the most important advantage was dietary. Large animals are more efficient at digestion than small animals, because food spends more time in their digestive systems. This also permits them to subsist on food with lower nutritive value than smaller animals. Sauropod remains are mostly found in rock formations interpreted as dry or seasonally dry, and the ability to eat large quantities of low-nutrient browse would have been advantageous in such environments. One of the tallest and heaviest dinosaurs known from good skeletons is ""Giraffatitan brancai"" (previously classified"
"contained fungi, decomposed wood material and detritus-eating invertebrates, all of which would have been nutritious. Tyrannosaur tooth marks are the most commonly preserved feeding traces of carnivorous dinosaurs. It is usually not possible to identify tooth marks on bone made by small predatory dinosaurs due to similarities in the denticles on their teeth. However, there are exceptions, like an ornithomimid caudal vertebra that has tooth drag marks attributed to ""Saurornitholestes"" and a partial ""Troodon"" skeleton with preserved puncture marks. Small bones of small theropods that were preyed upon by larger ones may have been swallowed whole and digested frequently enough"
"polished quartz pebbles associated with the remains of plesiosaurs and sauropod dinosaurs and interpreted these stones as gastroliths. In 1907, Barnum Brown found gravel in close association with the fossil remains of the duck-billed hadrosaur ""Claosaurus"" and interpreted it as gastroliths. Brown was among the first paleontologist to recognize that dinosaurs used gastroliths in their digestive systems to aid in the grinding of food. This interpretation, however, has been regarded as unconvincing by other paleontologists over the years. In 1932, Friedrich von Huene found stones in Late Triassic sediments, in association with the fossil remains of the prosauropod ""Sellosaurus"" and"
"crown was greater than that of the root for the teeth of most ""prosauropods"", including ""Plateosaurus""; this results in a cutting edge similar to those of extant herbivorous or omnivorous reptiles. Paul Barrett proposed that prosauropods supplemented their herbivorous diets with small prey or carrion. So far, no fossil of ""Plateosaurus"" has been found with gastroliths (gizzard stones) in the stomach area. The old, widely cited idea that all large dinosaurs, implicitly also ""Plateosaurus"", swallowed gastroliths to digest food because of their relatively limited ability to deal with food orally has been refuted by a study on gastrolith abundance, weight,"
"nostrils than others, their olfactory abilities were presumably lesser, as in modern piscivorous animals, and they may instead have used other senses (such as vision and mechanoreception) when hunting fish. Olfaction may have been more useful for spinosaurids that also fed on terrestrial prey, such as baryonychines. A 2018 study by the French palaeontologist Auguste Hassler and colleagues of calcium isotopes in the teeth of North African theropods found that spinosaurids had a mixed diet of fish and herbivorous dinosaurs, whereas the other theropods examined (abelisaurids and carcharodontosaurids) mainly fed on herbivorous dinosaurs. This indicates ecological partitioning between these theropods,"
"and the rest of its skull. The team found the dinosaur's upper jaws pushed outwards and sideways while chewing, as the lower jaw slid against the upper teeth. This chewing method is called pleurokinesis. During pleurokinesis, the maxilla bones slide laterally outward from the mouth. This is accomplished with a hinge made of the joints between the premaxilla and maxilla bones and the lacrimal and prefrontal bones. Pleurokinesis allows for the teeth to more precisely grind against one another, for better shearing of plant material, and reduces the stress that chewing puts on the skull. Analysis of the wear patterns"
"Gizzard The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including archosaurs (pterosaurs, crocodiles, alligators, and dinosaurs, including birds), earthworms, some gastropods, some fish, and some crustaceans. This specialized stomach constructed of thick muscular walls is used for grinding up food, often aided by particles of stone or grit. In certain insects and molluscs, the gizzard features chitinous plates or teeth. The word ""gizzard"" comes from the Middle English ""giser"", which derives from a similar word in Old French ""gésier"", which itself evolved from the Latin"
"endotherms, the larger forms could have been inertial homeotherms, or that many dinosaurs could have had intermediate metabolic rates. The earliest dinosaurs were almost certainly predators, and shared several predatory features with their nearest non-dinosaur relatives like ""Lagosuchus"", including: relatively large, curved, blade-like teeth in large, wide-opening jaws that closed like scissors; relatively small abdomens, as carnivores do not require large digestive systems. Later dinosaurs regarded as predators sometimes grew much larger, but retained the same set of features. Instead of chewing their food, these predators swallowed it whole. The feeding habits of ornithomimosaurs and oviraptorosaurs are a mystery: although"
"or hidden away under algae in rock pools. It is an opportunistic scavenger but the bulk of its diet comes from the film of bacteria and diatoms that exist on the surface of rocks. It feeds by everting its stomach (turning it inside out) against the surface of the rock and secreting enzymes which digest the film. Other foods found in its stomach included decaying toothed wrack (""Fucus serratus""), periwinkle faeces and bits of dead molluscs such as mussels (""Mytilus edulis""), oysters (""Ostrea edulis"") and periwinkles (""Littorina littorea""), but 95% of the stomachs contained no large particles indicating the importance"
"indicated that autoimmune (MRL/lpr) mice readily consume solutions with cyclophosphamide, an immunosuppressive drug that prevents inflammatory damage to internal organs. However, further studies provided contradictory evidence. Many animals eat soil or clay, a behaviour known as ""geophagy"". Clay is the primary ingredient of kaolin. It has been proposed that for primates, which can logically be extended to other animals, there are four hypotheses relating to geophagy in alleviating gastrointestinal disorders or upsets: Furthermore, two hypotheses pertain to geophagy in supplementing minerals and/or elements: Tapirs, forest elephants, colobus monkeys, mountain gorillas and chimpanzees seek out and eat clay, which absorbs intestinal"
"bulks of swallowed prey flesh and bone. Many large crocodilians swallow stones (called gastroliths or stomach stones), which may act as ballast to balance their bodies or assist in crushing food, similar to grit ingested by birds. Herodotus claimed that Nile crocodiles had a symbiotic relationship with certain birds, such as the Egyptian plover, which enter the crocodile's mouth and pick leeches feeding on the crocodile's blood; with no evidence of this interaction actually occurring in any crocodile species, it is most likely mythical or allegorical fiction. Since they feed by grabbing and holding onto their prey, they have evolved"
"Ornithopods, a group of dinosaurs including the Hadrosaurids (""duck-bills""), developed teeth analogous to mammalian molars and incisors during the Cretaceous period; this advanced, cow-like dentition allowed the creatures to obtain more nutrients from the tough plant life. This may have given them the advantage needed to usurp the formidable sauropods, who depended on gastroliths for grinding food, from their ecological niches. They eventually became some of the most successful animals on the planet until the Cretaceous–Paleogene extinction event wiped them out. The process of chewing has, by analogy, been applied to machinery. The U.S. Forest Service uses a machine called"
"CT scan comparisons of the skulls of ""Stegoceras validum"", ""Prenocephale prenes"", and several head-striking artiodactyls have also supported pachycephalosaurids as being well-equipped for head-butting. Scientists do not yet know what these dinosaurs ate. Having very small, ridged teeth they could not have chewed tough, fibrous plants as effectively as other dinosaurs of the same period. It is assumed that pachycephalosaurs lived on a mixed diet of leaves, seeds, and fruits. The sharp, serrated teeth would have been very effective for shredding plants. Nearly all ""Pachycephalosaurus"" fossils have been recovered from the Lance Formation and Hell Creek Formation of the western"
"excess heat through their skin. Like other reptiles, dinosaurs are primarily uricotelic, that is, their kidneys extract nitrogenous wastes from their bloodstream and excrete it as uric acid instead of urea or ammonia via the ureters into the intestine. In most living species, uric acid is excreted along with feces as a semisolid waste. However, at least some modern birds (such as hummingbirds) can be facultatively ammonotelic, excreting most of the nitrogenous wastes as ammonia. They also excrete creatine, rather than creatinine like mammals. This material, as well as the output of the intestines, emerges from the cloaca. In addition,"
"for grinding food, but when joined together with other teeth they would form a large surface area for the mechanical digestion of tough plant materials. This type of dental strategy is observed in ornithopod and ceratopsian dinosaurs as well as the duck-billed hadrosaurs, which had more than one hundred teeth in each dental battery. The teeth of carnivorous dinosaurs, called ziphodont, were typically blade-like or cone-shaped, curved, with serrated edges. This dentition was adapted for grasping and cutting through flesh. In some cases, as observed in the railroad-spike sized teeth of ""Tyrannosaurus rex"", the teeth were designed to puncture and"