Plant fossil analysis teaches us that the species of plants we see on the planet today are only a small sampling of all the species that have existed throughout the history of the world. Botanists frequently use gene sequence analysis to compare living plants based on their shared ancestry.
But how have scientists been able to research and classify plant species that have long since gone extinct? This is where the field of Paleobotany comes in.
Analyzing Plant Fossil Evidence
Biomolecules found in the plant fossil record can be a great source of information, if well preserved. DNA degrades too quickly to be useful for anything that is more than a million years old, so DNA evidence is not particularly useful for most long-extinct plant species.
However, there are some studies that skin pigment molecules and collagen can be preserved in animal fossils for tens to hundreds of millions of years. This has led some scientists to suspect that similar long-lasting molecules found inside plant fossils could help to determine how extinct plant groups fit into the overall historical botanical picture.
Most plants, for instance, have an outer waxy layer on their leaves, which exists to prevent water loss and protect the epidermal cells underneath this cuticle layer. This layer is extremely resilient. In fact, scientists have found preserved fossilized plant cuticles from land plants that existed more than 400 million years ago.
Because the cuticle layer is so resilient, the changes that occur in the fossils when they are buried and subsequently heated in the earth do not destroy the signature biochemical qualities of that original cuticle.
A Practical Example Of Plant Fossil Research
A group of scientists used this leaf cuticle fossil resilience to determine how the various seed plants that are known to have existed in the Mesozoic Era related to each other. They used Fourier transform infrared (FTIR) spectroscopy to locate a series of biomolecular patterns for modern cuticles from conifers, such as a cycad and ginkgo. They also studied other plant fossil cuticles from the same groups, and leaves from various other seed plant groups.
Ultimately, scientists were able to determine similarities not just between existing plant cuticles, but historical ones, showing that biomolecular signatures can be recovered from plant fossil cuticles to help people today, millions of years later, understand how extinct plant groups connect to the plants we know today.
The field of Paleobotany is constantly evolving, especially as the technologies available to us today continue to grow in sophistication. For more information about Paleobotany and its benefits, contact us today. The SoilAdvocates team is ready to help.