The scientist who studies fossils is called a paleontologist. Paleontology is the scientific exploration of the life of the past, seeking to understand the history of life on Earth, tracing the patterns of evolution, extinction, and changing ecosystems. A fossil is defined as any preserved remains, impression, or trace of a once-living organism from a past geological age, typically older than 10,000 years. By analyzing these ancient remains, paleontologists reconstruct the anatomy, behavior, and environment of prehistoric life forms.
Defining the Study of Ancient Life
Paleontology sits at the intersection of biology and geology, using the evidence of ancient life to understand Earth’s history. The discipline spans from the earliest signs of microbial life nearly four billion years ago up to the current Holocene epoch. This vast temporal framework is often referred to as “deep time,” which helps scientists grasp the planet’s 4.54-billion-year history and the gradual processes that shaped it.
The field relies on the fossil record, which includes petrified bones and shells, trace fossils (such as footprints and burrows), and chemical fossils (molecular remnants of ancient organisms). Paleontologists use these preserved materials as direct evidence of past life. They interpret the fossil evidence to classify extinct organisms, determine their evolutionary relationships, and measure geologic time.
The role of the paleontologist is to act as a detective of deep time, using principles from both the life sciences and the earth sciences. They must understand the biological processes of ancient organisms while also interpreting the sedimentary rocks in which fossils are found. This dual focus allows them to place extinct species within a biological family tree and understand the environmental conditions they lived in. Ultimately, their work provides a continuous narrative of life’s development, including major events like mass extinctions and the rise of new life forms.
Specialized Fields of Paleontology
Paleontology is a collection of specialized sub-disciplines, each focused on a different type of ancient life. Vertebrate Paleontology focuses on organisms with backbones, such as fish, amphibians, reptiles, mammals, and, most famously, dinosaurs. These specialists analyze fossilized bones and teeth to reconstruct the anatomy and evolutionary history of ancient creatures.
Invertebrate Paleontology studies animals without backbones, which constitute the vast majority of the fossil record. This includes creatures like trilobites, mollusks, corals, and ammonites, often preserved as shells or impressions in sedimentary rock. The abundance of invertebrate fossils makes them useful for dating rock layers and reconstructing ancient marine environments.
Micropaleontology is the study of microscopic fossils, including single-celled organisms, pollen, spores, and tiny skeletal parts. These minute fossils are abundant and are often used by scientists to reconstruct past climates and to correlate rock strata across geographical distances.
Paleobotany is the specialty concerned with ancient plant life. It involves examining fossilized wood, leaves, seeds, and ferns to understand the evolution of plants and the composition of prehistoric terrestrial ecosystems.
Methodology of Fossil Discovery and Analysis
The work of a paleontologist begins with fieldwork, involving surveying geological formations to locate promising fossil-bearing sites. Once a site is identified, excavation begins, using tools ranging from heavy machinery to delicate picks and brushes to expose the remains. Field researchers meticulously document the location of every specimen, as this contextual information is essential for later analysis.
After collection, the fossils are transported to a laboratory for preparation, a process that can take hundreds or thousands of hours for a single specimen. Technicians carefully remove the surrounding rock matrix using small mechanical tools or mild acids. Delicate fossils are often stabilized with glues and resins to prevent disintegration.
A primary step in the analysis phase is determining the age of the fossil and its surrounding rock layers. Paleontologists employ various dating techniques, categorized as relative and absolute dating. Relative dating methods, such as biostratigraphy, establish a chronological order of fossils based on their position in rock strata. Absolute dating techniques, such as radiometric dating, provide a numerical age by measuring the decay of radioactive isotopes. For example, the decay of Potassium-40 to Argon-40 can date rocks many millions of years old, while Carbon-14 dating is used for organic materials up to about 50,000 years old.
Paleontology Compared to Archaeology and Geology
Paleontology is often confused with other historical sciences, particularly archaeology and geology. Paleontology is the study of ancient life, focusing on the history of organisms and their evolution. Its timescale extends across billions of years, from the earliest life forms to the beginning of the modern era.
Archaeology, in contrast, is the study of past human cultures through the recovery and analysis of material remains, such as tools, pottery, and human-modified landscapes. The focus of archaeology is human history and prehistory, which generally spans a much shorter timescale, typically within the last few million years. A paleontologist who specializes in human evolution is called a paleoanthropologist.
Geology is the science that studies the physical structure, history, and processes of the Earth, including rocks, minerals, and landforms. Paleontology relies heavily on geology because fossils are found within rock layers. The geological context provides the necessary framework for dating and environmental reconstruction. Geologists provide the understanding of the Earth’s physical history, while paleontologists use the fossils found within those rocks to detail the history of life.