The rapidly expanding interest in, and availability of, digital tomography data to visualize cast... more The rapidly expanding interest in, and availability of, digital tomography data to visualize casts of the vertebrate endocranial cavity housing the brain (endocasts) presents new opportunities and challenges to the field of comparative neuroanatomy. The opportunities are many, ranging from the relatively rapid acquisition of data to the unprecedented ability to integrate critically important fossil taxa. The challenges consist of navigating the logistical barriers that often separate a researcher from high-quality data and minimizing the amount of non-biological variation expressed in endocasts - variation that may confound meaningful and synthetic results. Our purpose here is to outline preferred approaches for acquiring digital tomographic data, converting those data to an endocast, and making those endocasts as meaningful as possible when considered in a comparative context. This review is intended to benefit those just getting started in the field but also serves to initiate fur...
Between hatching and late adulthood American alligators Alligator mississippiensis show up to 700... more Between hatching and late adulthood American alligators Alligator mississippiensis show up to 7000-fold increases in body mass. Concurrent with such changes in body size are absolute and relative modifications in rostral proportions, dental form, feeding capacities and dietary preferences. How these major anatomical changes accommodate prey-resource shifts is poorly understood. In this study, we focus on the effects of ontogenetic changes in bite-force capacities and dental form to address how these factors relate to tooth-pressure generation and diet. We derive absolute values of tooth pressure along the crowns of the most prominent teeth (the first documentation of tooth pressures throughout ontogeny and after initial tooth contact for any animal) and show that these pressures increase with positive allometry during ontogeny. In addition, we discuss how American alligator tooth-pressure values explain their capacities for seizure and oral processing of typical prey, and how tooth-...
ABSTRACT—We report the discovery of a specimen of Tenontosaurus tilletti from the Cloverly Format... more ABSTRACT—We report the discovery of a specimen of Tenontosaurus tilletti from the Cloverly Formation that bears lesions we interpret as bite marks of Deinonychus antirrhopus. Some of the bite marks are in the form of exceptionally deep punctures through the long bone cortices. These provide a rare opportunity to estimate the bite-force capacities of this taxon through tooth indentation simulations. These experiments showed that approximately 4100 N of bite force were required to generate one of the bite marks, and 8200 N would have been generated simultaneously at a distal-most tooth position. These values are higher than those reported for large carnivoran mammals but similar to values recorded for comparably sized crocodilians. Although current evidence does not indicate how D. antirrhopus actually used its claws and teeth to acquire prey resources, it is clear that large individuals were capable of generating forces great enough to bite through bone.
The rapidly expanding interest in, and availability of, digital tomography data to visualize cast... more The rapidly expanding interest in, and availability of, digital tomography data to visualize casts of the vertebrate endocranial cavity housing the brain (endocasts) presents new opportunities and challenges to the field of comparative neuroanatomy. The opportunities are many, ranging from the relatively rapid acquisition of data to the unprecedented ability to integrate critically important fossil taxa. The challenges consist of navigating the logistical barriers that often separate a researcher from high-quality data and minimizing the amount of non-biological variation expressed in endocasts - variation that may confound meaningful and synthetic results. Our purpose here is to outline preferred approaches for acquiring digital tomographic data, converting those data to an endocast, and making those endocasts as meaningful as possible when considered in a comparative context. This review is intended to benefit those just getting started in the field but also serves to initiate fur...
Between hatching and late adulthood American alligators Alligator mississippiensis show up to 700... more Between hatching and late adulthood American alligators Alligator mississippiensis show up to 7000-fold increases in body mass. Concurrent with such changes in body size are absolute and relative modifications in rostral proportions, dental form, feeding capacities and dietary preferences. How these major anatomical changes accommodate prey-resource shifts is poorly understood. In this study, we focus on the effects of ontogenetic changes in bite-force capacities and dental form to address how these factors relate to tooth-pressure generation and diet. We derive absolute values of tooth pressure along the crowns of the most prominent teeth (the first documentation of tooth pressures throughout ontogeny and after initial tooth contact for any animal) and show that these pressures increase with positive allometry during ontogeny. In addition, we discuss how American alligator tooth-pressure values explain their capacities for seizure and oral processing of typical prey, and how tooth-...
ABSTRACT—We report the discovery of a specimen of Tenontosaurus tilletti from the Cloverly Format... more ABSTRACT—We report the discovery of a specimen of Tenontosaurus tilletti from the Cloverly Formation that bears lesions we interpret as bite marks of Deinonychus antirrhopus. Some of the bite marks are in the form of exceptionally deep punctures through the long bone cortices. These provide a rare opportunity to estimate the bite-force capacities of this taxon through tooth indentation simulations. These experiments showed that approximately 4100 N of bite force were required to generate one of the bite marks, and 8200 N would have been generated simultaneously at a distal-most tooth position. These values are higher than those reported for large carnivoran mammals but similar to values recorded for comparably sized crocodilians. Although current evidence does not indicate how D. antirrhopus actually used its claws and teeth to acquire prey resources, it is clear that large individuals were capable of generating forces great enough to bite through bone.
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Papers by PAUL GIGNAC
we interpret as bite marks of Deinonychus antirrhopus. Some of the bite marks are in the form of exceptionally deep punctures
through the long bone cortices. These provide a rare opportunity to estimate the bite-force capacities of this taxon through
tooth indentation simulations. These experiments showed that approximately 4100 N of bite force were required to generate
one of the bite marks, and 8200 N would have been generated simultaneously at a distal-most tooth position. These values are
higher than those reported for large carnivoran mammals but similar to values recorded for comparably sized crocodilians.
Although current evidence does not indicate how D. antirrhopus actually used its claws and teeth to acquire prey resources,
it is clear that large individuals were capable of generating forces great enough to bite through bone.
we interpret as bite marks of Deinonychus antirrhopus. Some of the bite marks are in the form of exceptionally deep punctures
through the long bone cortices. These provide a rare opportunity to estimate the bite-force capacities of this taxon through
tooth indentation simulations. These experiments showed that approximately 4100 N of bite force were required to generate
one of the bite marks, and 8200 N would have been generated simultaneously at a distal-most tooth position. These values are
higher than those reported for large carnivoran mammals but similar to values recorded for comparably sized crocodilians.
Although current evidence does not indicate how D. antirrhopus actually used its claws and teeth to acquire prey resources,
it is clear that large individuals were capable of generating forces great enough to bite through bone.