31. 古生物学paleontology
• 研究古地质时代中的生物及其发展的科学
• 通过化石在沉积岩中的排列来比较不同年代生物的变化
• 化石是存留在岩石中的古生物遗体、遗物或生活痕迹,
最常见的是骸骨和贝壳等
• 越古老的地层,生物结构越简单
This illustration shows an artist’s renderings of species derived
from fossils of the evolutionary history of the horse and its
ancestors. The species depicted are only four from a very diverse
lineage that contains many branches, dead ends, and adaptive
radiations. One of the trends, depicted here, is the evolutionary
tracking of a drying climate and increase in prairie versus forest
habitat reflected in forms that are more adapted to grazing and
predator escape through running.
48. Homologous
hox genes in
such different
animals as
insects and
vertebrates
control
embryonic
development
and hence the
form of adult
bodies. These
genes have
been highly
conserved
through
hundreds of
millions of
years of
evolution.