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Variation in aspects of the tympanic pneumatic system in a population of Allosaurus fragilis from the Morrison Formation (Upper Jurassic)
Ist Teil von
Journal of vertebrate paleontology, 1996-03, Vol.16 (1), p.63-66
Ort / Verlag
Taylor & Francis Group
Erscheinungsjahr
1996
Quelle
Taylor & Francis Journals Auto-Holdings Collection
Beschreibungen/Notizen
Diverticula of the tympanic pneumatic system were present lateral to the basicranium in Allosaurus, as evidenced by depressions on the basicranium and the presence of pneumatic foramina. An examination of an ontogenetic series of basicrania of A. fragilis shows this system to exhibit both ontogenetic and individual variation. Anteriorly, diverticula initially invade the basipterygoid process and withdraw with age (ontogenetic variation). Posteriorly, depressions for the diverticula are variably developed (individual variation). Although recesses on basipteryygoid processes are reported in several theropod families this condition is likely to be a parallelism.