Primitive armored fish; extinct NAME: Squid-like animal with coiled, chambered shell; related to modern-day Nautilus. Cartilage fish; many living species. Primitive form of chordate; floating form with radiometric dating continental drift stalks; extinct.
Each card represents a particular rock layer with a collection of fossils that are found in that particular rock stratum. Use this information to sequence the cards in a vertical stack of fossils in rock strata.
Clams and oysters; many living species NAME: Extinction of species is common; most of the species that have lived on the earth no longer exist. If the letters "T" and "C" represent datings index in the oldest rock layer, they are the oldest fossils, or the first fossils formed in the past for this sequence of rock layers.
Multibranched relative of starfish; lives attached to the ocean bottom; some living species "sea lilies" NAME: Scientists also use direct evidence from observations of the rock layers themselves to help determine the relative age of rock layers. Locally, physical characteristics of rocks can be compared and correlated.
The letters on the other cards have no significance to the sequencing procedure and should be ignored at this time. The fossils represented by the letters on this card are "younger" than the "T" or "C" fossils on the "TC" card which represents fossils in the oldest rock layer.
The "Who's On First? Arrange them from oldest to youngest with the oldest layer on the bottom and the youngest on top.
Now, look for a card that has either a "T" or "C" written on it. Sequence the remaining cards by using the same process.
Carnivore; air-breathing aquatic animal; extinct. The study of fossils and the exploration of what they tell scientists about past climates and environments on Earth can be an interesting study for students of all ages.
Primitive form of chordate; floating form with branched stalks; extinct NAME: Keep in dating index that extinction is forever. Return to top Procedure Set B: Scientific measurements such as radiometric dating use the natural radioactivity of dating a danish girl elements found in rocks to help determine their age.
Clams and oysters; many living species. Primitive armored fish; extinct. Once students begin to grasp "relative" dating, they can extend their knowledge of geologic time by exploring radiometric dating and developing a timeline of Earth's history.
Figure 2-A gives some background information on the individual fossils. Three-lobed body; burrowing, crawling, and swimming forms; extinct.