Omnivores come from diverse backgrounds that often independently evolved sophisticated consumption capabilities. For instance, dogs evolved from primarily carnivorous organisms (Carnivora) while pigs evolved from primarily herbivorous organisms (Artiodactyla). Despite this, physical characteristics such as tooth morphology may be reliable indicators of diet in mammals, with such morphological adaptation having been observed in bears.
All of these animals are omnivores, yet still fall into special niches in terms of feeding behavior and preferred foods. Being omnivores gives these animals more food security in stressful times or makes possible living in less consistent environments.
^Evans, Alistair R.; Pineda-Munoz, Silvia (2018), Croft, Darin A.; Su, Denise F.; Simpson, Scott W. (eds.), "Inferring Mammal Dietary Ecology from Dental Morphology", Methods in Paleoecology: Reconstructing Cenozoic Terrestrial Environments and Ecological Communities, Vertebrate Paleobiology and Paleoanthropology, Springer International Publishing, pp. 37–51, doi:10.1007/978-3-319-94265-0_4, ISBN978-3-319-94265-0
^Sacco, Tyson; Valkenburgh, Blaire Van (2004). "Ecomorphological indicators of feeding behaviour in the bears (Carnivora: Ursidae)". Journal of Zoology. 263 (1): 41–54. doi:10.1017/S0952836904004856. ISSN1469-7998.
^McCarty, John P.; Winkler, David W. (1 January 1999). "Foraging Ecology and Diet Selectivity of Tree Swallows Feeding Nestlings". The Condor. 101 (2): 246–254. doi:10.2307/1369987. JSTOR1369987.
^Superina, Mariella (1 March 2011). "Husbandry of a pink fairy armadillo (Chlamyphorus truncatus): case study of a cryptic and little known species in captivity". Zoo Biology. 30 (2): 225–231. doi:10.1002/zoo.20334. ISSN1098-2361. PMID20648566.