![]() ![]() ![]() Like their osteophagous carnivoran counterparts, these saurians have stomach acidity less than 1.5 pH 10, 12, enabling chemical digestion of ingested bones.Ĭarnivorous dinosaurs (Archosauria: Theropoda), including most tyrannosaurids, also possessed ziphodont teeth and routinely made shallow scores and, occasionally, bone indentations during feeding 13, 14, 15, 16. Exceptions are: (1) Komodo dragons ( Varanus komodoensis Squamata) with ziphodont (recurved and serrated) teeth that occasionally leave shallow scores on skeletal elements 6, 7 but do not crack them (2) large, blunt-toothed crocodylians (e.g., American alligator- Alligator mississippiensis Archosauria: Crocodylia), which puncture and occasionally crack bones when biting but do not finely fragment large sections of bones 8, 9 and (3) some vultures (Accipitridae, Cathartidae) that drop bones on hard substrates to access marrow 10, 11. ![]() Instead, they consume small carcasses in their entirety and large skeletal elements through dismemberment. On the other hand, extant carnivorous reptiles (Sauria-including birds ) typically possess non-occluding teeth, or in the case of modern birds lack them entirely, and cannot generate sufficient stress distributions to fragment bones. When necessary, mammals often employ repetitive, localized biting to finely comminute bones that are too large to swallow or crush. (Note: bone is weakest in shear as opposed to compressional or tensional loading, and whole elements almost exclusively rupture via this mode 4, 5). Many, such as grey wolves ( Canis lupus) and spotted hyenas ( Crocuta crocuta), use their occluding incisors and cheek teeth to produce tooth pressures exceeding cortical bone shear strength to promote bone fragmentation 1, 2, 3, 4. Carnivorous mammals (Carnivora) are the exception. Most vertebrates cannot generate sufficient tooth pressures to gain access to marrow and phosphatic minerals trapped within the major bones of large animals. rex to finely fragment bones and more fully exploit large dinosaur carcasses for sustenance relative to competing carnivores. Collectively, these capacities and behaviors allowed T. We show that bone pulverization was made possible through a combination of: (1) prodigious bite forces (8,526–34,522 newtons ) and tooth pressures (718–2,974 megapascals ) promoting crack propagation in bones, (2) tooth form and dental arcade configurations that concentrated shear stresses, and (3) repetitive, localized biting. rex feeding behaviour from trace evidence, estimated bite forces and tooth pressures, and studied tooth-bone contacts to provide the answer. How this mammal-like capacity was possible, absent dental occlusion, is unknown. Nevertheless, North American tyrannosaurids, including the giant (13 metres ) theropod dinosaur Tyrannosaurus rex stand out for habitually biting deeply into bones, pulverizing and digesting them. As a result, most reptilian predators can only consume bones in their entirety. Conversely, carnivorous reptiles have non-occluding dentitions that engender negligible bone damage during feeding. Most carnivorous mammals can pulverize skeletal elements by generating tooth pressures between occluding teeth that exceed cortical bone shear strength, thereby permitting access to marrow and phosphatic salts. ![]()
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