Nutrition, gastrointestinal morphology, and zoological classification
Naturalists, anatomists, physiologists, taxonomist and scientists like Aristotle (384-322 B.C.), Andrea Cesalpino (1519-1603), Rev. John Ray (1627-1705), Carl von Linne (1707-1778), J. B. P. A. Lamarck (1744-1829), Baron G. Cuvier (1769-1832), Charles Darwin (1809-1882) and Alfred Wallace (1823-1913), Ernest Haeckel (1834-1919), Sir Richard Owen (1804-1892), Robert Whittaker (1924-1980), and George Simpson (1902-1984) have observed, described, and grouped living organisms throughout history. Nutritionists have unsuccessfully contributed to mammalian classification, plausibly the cause for the missing link between zoological classification and nutrition.
Diets, feeding types, gastrointestinal length, dentition and four questions of a survey were used in this study as nutritional variables to determine if a combination of these characteristics could link a specific mammal to their preferred diet. One hundred and sixty three survey responses were received and the four questions used in this study addressed prehensile mechanisms, mastication, feeding type and food acquisition. Diets for 125 mammalian families were collected from literature and grouped into three major categories (polyphagic, phytophagic, and zoophagic). The latter two categories were subdivided into specific groups (phytophage: greens, high fiber substrate, and concentrate; zoophage: invertebrates, blood, and vertebrates). A third subdivision grouped families into specialized feeding patterns (greens: graminivore, folivore, and herbivore; concentrate: frugivore; invertebrates: arthropods, mollusks, and plankton; vertebrates: terrestrial and aquatic). Dentition (upper and lower jaw number of teeth and type) was collected from literature. Teeth type were evaluated as a function of total number of teeth. Fifty six gastrointestinal lengths (small intestine, cecum (if available), and large intestine) were collected from literature and eleven gastrointestinal lengths were measured postmortem. Gastrointestinal images were measured using computer software and evaluated as a function of body length.
Animals that use their tongue and lips as prehensile mechanisms, have a low number of teeth, high percent of molar and pre-molars, and long large intestine and cecum were categorized as phytophagic. Animals that use teeth as prehensile mechanism, have a high number of total teeth, high percent of incisors and canines, and short large intestine were categorized as zoophagic.