BACKGROUND:
Paleontology is the study of old (paleo-) life (-onto-). It is a
relatively new science in Western culture. The history of paleontology is a
very interesting case of the development of human thought. The influence of
religion prevented even the thought of extinct organisms for a long time.
Fossils were perceived as "oddities" of nature. Therefore, the
early scientific literature, from the Greeks until 1600's, was full of
explanations that included many myths and stories about objects that we now
know are fossils. Shiny, button-shaped fossil fish teeth were thought to
come from the heads of toads. Clam fossils were hoofs of sheep. Ammonites, a
sea animal similar to the modern Nautilus, were interpreted as coiled snakes
turned to stone by a saint. The fossil tusk of the narwhal, a small whale,
was for many years thought to be from the magical unicorn. Fossil oysters
were nicknamed the Devil's Toenails. The connection between fossils and now
extinct species was also an important breakthrough for a fuller
understanding of geologic time.
In many animals, the shape and relative position of bones determine the
general form of the animal. Land vertebrates evolved from freshwater or
marine vertebrates. This change entailed many modifications in the organisms’
limb bones, as their shape and function changed from fins used for balancing
or motion in water to legs used for weight-bearing and walking on land.
Limbs with digits replaced the paired fins, and the overall size and density
of the bones increased.
PROCEDURE:
- On their lab sheets, have the students attempt to pair the name of the
organism with the bones of its fore limb. Here are answers to guide you:
- The rhinoceros (#1) is heavy boned to support its weight.
- The monkey (#2) has an opposable thumb, capable of gripping
objects as do humans. Have students look at their hands to see their
opposable thumb
- The lizard's limb (#3) is long and can hold onto surfaces. The
turtle's foot (#4) is almost a web-like structure.
- The pelican limb (#5) is long and narrow, and shows a bird's
characteristic hollow, light weight structure.
