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Age Through Rocks
The type of rock associated with the starfish fossil gives scientists a chance to calculate how long ago the starfish existed. For example, starfish fossils found in certain rock in Victoria Province in Australia showed scientists that the starfish all existed around 430 million years ago, in the Silurian Period. In Travis County in Texas, starfish fossils are 85 million years old and from the Cretaceous Period.
Age Through Carbon Dating
Besides rock association, scientists can use Carbon-14 dating to determine the age of starfish by the decay of Carbon-14 isotopes. All organisms take in carbon throughout their lives. When the organism dies, the use of Carbon-14 stops. Scientists can use radioactive waves to measure the rate of Carbon-14 decay, thus giving the time and era the organism died in. As a result, scientists have determined that the oldest starfish came into existence in the Cambrian Era, which began over 533 million years ago.
Evolution Variation
Aging starfish fossils help scientists map out the evolutionary variation of starfish. Because starfish exist today, scientists can create an evolutionary map of how the starfish evolved, what species are extinct, and if there have been genetic variations, or slight adaptive changes, to the starfish over the span of millions of years. Interestingly, the starfish has not changed much since its inception on the Earth millions of years ago.
Environmental Insight
With the age of the starfish fossil calculated, many scientists study the environmental nature of that age. This is a general benefit of all fossils in that scientists can discover from the fossil remains what the climate and ocean conditions were like millions of years ago. For example, the existence of starfish fossils in Texas shows that 85 million years ago the ocean waters from the Gulf of Mexico must have penetrated deep into the American continent and then receded over time.
Extinction Events
Some starfish fossils coincide with large extinction events seen throughout the world. For example, if many of the starfish fossils are dated to the exact time or era of death, scientists might theorize that a massive or cataclysmic event destroyed the local population. This can be compared to events across the world to theorize if a planetary extinction event occurred.