Volcanic activity during the Tertiary has long been held
responsible for the deaths and subsequent fossilization of the
vertebrate populations of the John Day region in Oregon. Oreodonts
as plains or savannah dwelling ruminant herbivores, were likely to
have been subject to potential exposure throughout their lifetime
to volcanic debris...
Changes in blood calcium and phosphorus concentrations were
characterized for rainbow trout (Salmo gairdneri) and coho salmon
(Oncorhynchus kisutch) following intense exercise or exposure to
suspended volcanic ash or topsoil. Significant elevations in blood
calcium and phosphorus accompanied exercise-induced acidemia in both
S. qairdneri and O. kisutch. These elevations persisted...
Winters in north-temperate climates impose high
thermogenic demands upon small birds which are met by
seasonal acclimatization. This thesis investigates the
extent and mechanisms of seasonal acclimatization in darkeyed
juncos (Junco hyemalis) inhabiting western Oregon.
Although insulation is significantly increased in
winter, acclimatization is primarily metabolic. Increased
metabolism is required...
Using techniques that permit the direct observation of
fetuses in vivo, prenatal behavioral development was
compared among four species in the rodent family Muridae:
the Norway rat (Rattus norvegicus), Mongolian gerbil
(Meriones unguiculatus), cotton rat (Sigmodon hispidus), and
spiny mouse (Acomys cahirinus). Rattus and Meriones bear
altricial offspring, as do...
Long-term subae lal survival has been anecdotally noted
in the staghorn sculpin, Leptocottus armatus. In this study,
I quantified this phenomenon physiologically by examining the
following parameters: standard metabolic rate and indications
of reduced standard metabolic rate during subaerial exposure;
capacity for and mechanism(s) of oxygen consumption in air;
capacity...
Although endothermy is one of the most significant evolutionary developments in the vertebrates, its origins among extinct taxa have traditionally been difficult to determine. Endothermy is primarily an attribute of the "soft anatomy," and its key features, such as complex lungs, elevated blood oxygen carrying capacity and mitochondrial density, do...
Inferences regarding the biology of extinct taxa are often founded primarily
on cladistically-based phylogenetic hypotheses. However, these inferences are
frequently inconsistent with the morphology and physiology of modern animals. I
suggest that reference to the biology of modern animals might be a more
appropriate tool to aid in the reconstruction...
Dinosaurs represent one of the most successful evolutionary radiations of terrestrial vertebrates, with a myriad of forms that dominated the terrestrial environment for over 180 million years. Despite the fact that dinosaurs are the focus of extensive popular and scholarly investigation, relatively little is actually known of their biology. The...
The purpose of this study was to identify any ostelogical features which might prevent
paradoxical movement (=lateral collapse) of the abdominal air sacs in birds during inhalation.
A combination of 26 fresh and frozen adult bird carcasses representing 10 avian orders were
procured from local sources. Dissections of each specimen...
Little, if any, quantifications have been made on the contribution of the vertebral column during jumping in quadrupedal mammals. Previous studies of jumpers have focused on the morphological and physiological specializations of the hindlimbs. In this study, such specialization was measured during the supramaximal jumps of the Pacific jumping mouse...