Fossil studies can provide valuable insights into a variety of natural phenomena, including the formation of well-known spirals in nature. A 3D model of a 407-million-year-old plant fossil has changed how scientists think about the evolution of leaves. The study has also revealed new information about the spectacular patterns found in plants.
Leaf arrangements in the earliest plants differ from those in most modern plants, contradicting a long-held theory about the origins of a well-known mathematical pattern found in nature, according to new research. According to the findings, the arrangement of leaves into distinctive spirals, which is common in nature today, was not common in the most ancient land plants that first populated the earth’s surface.
Instead, the ancient plants were discovered to have a different type of spiral. This contradicts a long-held theory about the evolution of plant leaf spirals, which suggested that they evolved along two distinct evolutionary paths. Spirals are common in nature, whether they are the vast swirls of a hurricane or the intricate spirals of the DNA double-helix, and most can be described by the famous mathematical series the Fibonacci sequence.
In the fossil record, the clubmoss Asteroxylon mackiei is one of the earliest examples of a plant with leaves. We were able to track individual spirals of leaves around the stems of these 407 million year old fossil plants using these reconstructions. Our study of Asteroxylon leaf arrangement reveals that very early clubmosses developed non-Fibonacci spiral patterns.
Holly-Anne Turner
This sequence, named after the Italian mathematician Leonardo Fibonacci, serves as the foundation for many of nature’s most efficient and stunning patterns. Spirals are common in plants, with Fibonacci spirals accounting for more than 90% of all spirals. These distinctive spirals can be found in the flower petals, leaves, or seeds of sunflower heads, pinecones, pineapples, and succulent houseplants.
For centuries, scientists have puzzled over why Fibonacci spirals, also known as nature’s secret code, are so common in plants, but their evolutionary origin has been largely overlooked. Fibonacci spirals have long been thought to be an ancient feature that evolved in the earliest land plants and became highly conserved in plants due to their widespread distribution.
An international team led by the University of Edinburgh, however, has debunked this theory by discovering non-Fibonacci spirals in a 407-million-year-old plant fossil. The researchers created the first 3D models of leafy shoots in the fossil clubmoss Asteroxylon mackiei, a member of the earliest group of leafy plants, using digital reconstruction techniques.
The fossil was discovered in the well-known Rhynie chert, a Scottish sedimentary deposit near the Aberdeenshire village of Rhynie. The site contains evidence of some of the planet’s earliest ecosystems, when land plants first evolved and gradually began to cover the earth’s rocky surface, allowing it to be habitable.
The findings revealed that Asteroxylon mackiei leaves and reproductive structures were most commonly arranged in non-Fibonacci spirals, which are uncommon in plants today. This changes scientists’ perceptions of Fibonacci spirals in land plants. It suggests that non-Fibonacci spirals were common in ancient clubmosses and that the evolution of leaf spirals split into two distinct paths.
The leaves of ancient clubmosses had an entirely distinct evolutionary history to the other major groups of plants today such as ferns, conifers and flowering plants.
The team created the 3D model of Asteroxylon mackiei, which has been extinct for over 400 million years, by working with digital artist Matt Humpage, using digital rendering and 3D printing. The research, published in the journal Science, was funded by UK Research and Innovation (UKRI), The Royal Society and the German Research Foundation.
The study also involved researchers from, University College Cork, Ireland, University Münster, Germany and Northern Rogue Studios, UK. Dr Sandy Hetherington, an evolutionary palaeobiologist and the project’s lead at the University of Edinburgh, said:
“For the first time, we can examine leaf arrangement in 3D using our model of Asteroxylon mackiei. The ability to 3D print a 407-million-year-old plant fossil and hold it in your hand is truly amazing. Our findings shed light on the evolution of Fibonacci spirals in plants.”
Holly-Anne Turner, who worked on the project as an undergraduate student at the University of Edinburgh and is first author of the study, said:
“In the fossil record, the clubmoss Asteroxylon mackiei is one of the earliest examples of a plant with leaves. We were able to track individual spirals of leaves around the stems of these 407 million year old fossil plants using these reconstructions. Our study of Asteroxylon leaf arrangement reveals that very early clubmosses developed non-Fibonacci spiral patterns.”
