Study of fossils found in arctic shows plants more developed at earlier time

Along with Canadian colleagues, a University of North Carolina at Chapel Hill scientist has discovered fossils of plants dating back some 420 million years.

The discovery, made on Bathurst Island in the Northwest Territories about 800 miles from the North Pole, shows vascular plants were more complex at that time than paleontologists previously believed and is significant for that reason, the UNC researcher said.

“These are not the earliest vascular plants ever found, but they are the earliest ever found of this size, complexity and degree of diversification,” said Dr. Patricia G. Gensel, professor of biology at UNC. “They look something like medium-sized grasses, except that they branch.”

The discovery adds to the sparse record of early land plants known from North America, Gensel said. Previously, most information on ancient plants has been based on fossils from Wales, Venezuela and China.

A report about the findings appears in the June issue of the American Journal of Botany. Besides Gensel, authors are UNC graduate student Michele E. Kotyk, Dr. James F. Basinger, professor of geology at the University of Saskatchewan, and Dr. Tim A. de Freitas, a Calgary, Canada geologist working for Nexen Inc.

Bits and pieces of the earliest known land plants date back almost 500 million years to the Ordovician Period, and their fragmentary remains indicate the plants were related to liverworts that exist today, Gensel said. The earliest vascular plants — ones with water-conducting tissues — so far are known to date back about 425 million years. Sparsely branched, they were about an eighth of an inch tall and grew a few reproductive bodies known as sporangia on their branches.

By contrast, the new plants, which lived only a few million years later, would have stood four or more inches tall, bore many branches with dense rows of sporangia and probably grew in clusters, she said. They more closely resembled much younger early Devonian plants from about 390 million years ago than any other Silurian forms.

“We found these previously unknown plants in rocky sediments we collected and brought back first by helicopter and then airplane from Bathurst in 1994,” the biologist said. “Because of permafrost, digging is impossible, and we picked them up and chipped them out from exposed slopes on the almost completely barren island. Although we worked in July, some days it stayed near freezing all day long. When these plants were alive this land lay near the equator.”

The team dated specimens by finding them in the same layers as several tiny invertebrate fossilized animals such as graptolites, which under the microscope resemble band saw blades, and conodonts, which resemble miniature jaws and teeth and represent the mouthparts of primitive vertebrates. Such animal remains are excellent index fossils – fossils that indicate time.

“We conclude that the Bathurst Island flora presents the best evidence to date of substantial diversity of form, complexity and stature of vascular plants in this period,” Gensel said.

In 1996, she and colleagues in Virginia and Northern Ireland reported finding fossils of scorpions, millipedes and related arthropods dating back almost 400 million years. Those creatures, which predated dinosaurs and other reptiles by some 50 million to 100 million years, were the largest animals ever found on land up to that time in North America.

“Much of science is devoted to understanding and curing diseases, and that’s as it should be,” Gensel said. “However, we also need to understand where living things have come from, which we can do by studying fossils. That gives us a better perspective on why the Earth and life are as they are today.”

Note: Gensel can be reached at (919) 962-6937 or pgensel@bio.unc.edu
Contact: David Williamson, (919) 962-8596.

Media Contact

David Williamson EurekAlert

All latest news from the category: Life Sciences and Chemistry

Articles and reports from the Life Sciences and chemistry area deal with applied and basic research into modern biology, chemistry and human medicine.

Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.

Back to home

Comments (0)

Write a comment

Newest articles

Lighting up the future

New multidisciplinary research from the University of St Andrews could lead to more efficient televisions, computer screens and lighting. Researchers at the Organic Semiconductor Centre in the School of Physics and…

Researchers crack sugarcane’s complex genetic code

Sweet success: Scientists created a highly accurate reference genome for one of the most important modern crops and found a rare example of how genes confer disease resistance in plants….

Evolution of the most powerful ocean current on Earth

The Antarctic Circumpolar Current plays an important part in global overturning circulation, the exchange of heat and CO2 between the ocean and atmosphere, and the stability of Antarctica’s ice sheets….

Partners & Sponsors