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Bird brains and reproductive organs: clues to dinosaur behavior and anatomy?
From: Ben Creisler
A couple of recent papers and a news story about features of bird anatomy that
might be clues to theropod behavior...
Lesley J. Rogers ("2011")
The two hemispheres of the avian brain: their differing roles in perceptual
processing and the expression of behavior.
Journal of Ornithology (advance online publication)
free pdf: http://www.springerlink.com/content/h7q6u4658207kr18/fulltext.pdf
The hemispheres of the avian brain are specialized to carry out different
functions. Since each eye sends its input mainly to the contralateral
hemisphere, birds respond differently to stimuli seen with the left eye than
they do to stimuli seen with the right eye. The right hemisphere attends to
novel stimuli, which easily distract it from ongoing functions. It assumes
control in emergency or stressful conditions. The left hemisphere attends to
learnt categories and controls behavior in routine, non-stressful situations.
This division of function extends to processing of auditory, olfactory and even
magnetic stimuli. Evidence for this comes from a number of avian species, and
has been shown in both laboratory and field tests. Knowledge of these
specializations is relevant to understanding the behavior of birds in the wild
since birds respond in different ways to stimuli on their left and right sides
(e.g. preferential response to predators and
conspecific on the left side and to prey on the right side) and they choose to
view different stimuli with the left or right eye. Individual differences in
the strength of visual lateralization are determined by exposure of the embryo
to light, versus incubation in the dark, and by the levels of steroid hormones
in ovo. The importance of these influences on lateralization is discussed in
terms of behavior in the natural habitat. The potential importance of
hemispheric dominance in the welfare of birds is also considered.
P. L. R. Brennan & R. O. Prum ("2011")
The erection mechanism of the ratite penis.
Journal of Zoology (advance online publication)
The erection mechanism of the penis in most vertebrates is blood vascular. A
major evolutionary transition occurred in birds, where the erection mechanism
changed from blood vascular to lymphatic. Within birds, however, the erection
mechanism of the ratite penis has remained unknown. Early work suggested that
the erection mechanism in ostrich Struthio camelus was blood vascular while no
description existed for the emu Dromaius novaehollandiae or the rhea Rhea
americana. Because the penis in all other described birds has a lymphatic
erection mechanism, clarifying that the erection mechanism of ratites is of
great importance to understanding one of the major evolutionary transitions of
penis morphology within amniotes. Here, we show that the erection mechanism of
ratites is lymphatic, confirming that the evolutionary transition to lymphatic
erection occurred in the last common ancestor of Aves.
Ostrich penis clears up evolutionary mystery