j. c. gaulin examined 102 primate species (from various scientific literature) for links between size and diet, and hence the jarman–bell principle. omnivorous primates seemed inconsistent with the trend, likely due to the diversity of their diet. carnivorous diets aye-aye. note the elongated fingers for echo-locating prey. the aye-aye is a large primate for its nearly exclusive insectivorous diet. this seems inconsistent with the jarman–bell principle. however, specialised adaptations, such as large ears and elongated fingers for echo- locating larvae, allow the aye aye to subside on such diet. this supports the idea that the jarman- bell principle is not universal, and that depending on the circumstances (in this case, specialised adaptations), the expected trend is not followed. a western lowland gorilla eating herbivorous food herbivorous diets colobines which feed heavily on low- quality food display ruminant like qualities such as digestion via symbiotic microbes in a separate forestomach. the weasel sportive lemur are extremely small folivores. they practice coprophagy to maximise nutrient extraction. the western gorilla are large and highly herbivorous; their diet contains 90% herbivorous food. omnivorous diets baboon out in the open country biome omnivorous cercopithecoids such as baboons and the patas monkey display the second largest average body mass. humans feature such a diverse range of diet that they don't rely on one particular food group. both of the above omnivores and the majority of primate omnivores live in open ranges, particularly ecotonal regions (where two biomes meet). in these environments, food abundance is comparatively lower than forest biomes. the diet would shift to a mixture of low amounts of high-quality food, and high amounts of low-quality food to maximise forage and energy. the universality of the jarman–bell principle deviations from the expected trend question the universality of the principle. steven j. c. gaulin notes that, when the principle is applied to offer any type of explanation, it is subjected to numerous other phenomena that occur at the same time. for example, the habitat range constrains the size of an organism; large primates are too heavy to live on tree tops. or perhaps the use of adaptations or even tools were enough to allow viable consumption of food quality that would not otherwise be sufficient. gigantism in dinosaurs extinct dinosaurs, particularly the large sauropods, can be imagined primarily through two methods. method one involves fossil records; bones and dentition. method two involves drawing ideas from extant animals and how their body mass is linked with their diet. comparing digestion in extant, herbivorous reptiles and mammals and relating this to sauropod gigantism reptiles generally have a shorter retention time than mammals. however, this loss of digestive efficiency is offset by their ability to process food into smaller particles for digestion. smaller particles are more easier to digest and ferment. as sauropods are reptiles, it would be expected that they have a similar retention time to extant reptiles. however, the lack of particle reduction mechanisms (e.g. gastric mills, chewing teeth), challenge the validity of this expectation. marcus clauss et al. hypothesised that sauropods have a very enlarged gut capacity to account for this. retention time is inversely proportional to intake amount. therefore, an enlarged gut cavity allows increased intake, and thus shorter retention time similar to other herbivorous reptiles. nutrient constraints d. m. wilkinson and g. d. ruxton considered the available nutrients as a driving factor for sauropod gigantism. sauropods appeared during the late triassic period and became extinct at the end of the cretaceous period. during this time period, herbivorous plant matter such as conifers, ginkgos, cycads, ferns and horsetails may have been dietary choice of sauropods. these plants have a high carbon/ nitrogen content. large amounts of these plant matter would be consumed to meet the bodily nitrogen requirement. hence, more carbon content is consumed than required. clauss hummel et al. (2005), cited in d. m. wilkinson and g. d. ruxton's paper, argues that larger sizes does not necessarily improve digestive efficiency. rather, it allows nutrient prioritisation. for example, if there exists a diet with high carbon but low nitrogen content, then meeting the nitrogen dietary requirement suggests consuming a high level of carbon diet. since gut volume scales linearly with body mass, larger animals have more capacity to digests food.