Dinosaurs under the Aurora (Life of the Past) by Roland A. Gangloff

Author:Roland A. Gangloff [Неизв.]
Language: eng
Format: epub, azw3, mobi
ISBN: 9780253007186
Publisher: Indiana University Press
Published: 2012-07-10T04:00:00+00:00

Fig. 6.9. Examples of bite marks on bones of Edmontosaurus from the Liscomb Bone Bed, scale = 2 centimeters. A. Two tooth pits on ventral surface of pedal phalanx 1, digit III. B. Parallel tooth scores on skull fragment. C. Two tooth pits on dorsal surface of right pedal phalanx 1, digit II. D. Three tooth scores on surface of right radius. E. Four parallel tooth scores on indeterminate limb bone fragment. Arrows indicate tooth scores. Credit: Roland Gangloff and Anthony Fiorillo.

Troodontids (Troodon, Saurornithoides, Sinornithoides, Sinovenator, and Borogovia) had brains that compare, in size, with modern flightless birds such as the emu and ostrich. The brain was equipped with large optic processing centers and a large middle ear cavity.51 This combination most likely gave Troodon a highly developed light-gathering optic system that would have provided image acuity allowing for a high degree of detail discrimination.52 This visual system, combined with great hearing acuity and good balance, would have been a dynamite toolkit for a predator that overwintered and hunted during at least seven months of continuous darkness and twilight in the Arctic. These adaptations would have given Troodon an advantage over contemporaneous Arctic Alaskan carnivores such as tyrannosaurids and dromaeosaurs in preying upon Edmontosaurus, The herbivore taxon that most likely overwintered based on the preponderance of evidence.53 Troodon’s smaller size may have allowed it to resort to denning and deep sleep during unusual cold spells, something that the larger theropods could not have done.54 Unfortunately, this preliminary hypothesis cannot be tested yet. There are, at present, none of the proper Troodon bones from Alaska that would allow for the proper analysis—presence or absence of lines of arrested growth.

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