Fossilized Pollen Suggests Flowering Plants Evolved 250 Million Years Ago

Fossilized pollen from the Triassic Period 250 million years ago
Credit: University of Zürich

Using Confocal Laser Scanning Microscopy, scientists have imaged fossilized pollen grains from Northern Switzerland that dates the evolution of flowering plants to the early Triassic Period around 252 to 247 million years ago. The three dimensional high resolution images of six different types of pollen also suggest that the plants were pollinated by insects.

The Triassic period extends to about 250 to 200 million years ago and is the first period of the Mesozoic Era. This period lies between the Permian and Jurassic periods.

During the Triassic period, the Earth's climate was generally hot and dry and that there are no evidence of glaciers at or near the north and south pole. During this time, the polar regions were moist and temperate. It would have a climate that is suitable for forests and vertebrarates.

The Earth's continents would not have existed then. The land mass of the planet then was one gigantic continent called Pangea. The climate on Pangea was seasonal having hot summers and cold winters.

Plant life during this time was believed to include lycophytes, cycads, ginkgophyta (represented in modern times by Ginkgo biloba) and glossopterids. Seed plants such as spermatophytes are abundant in the north while Glossopteris (a seed fern) was the dominant tree in the southern hemisphere.

The discovery of the pollen would place the appearance of flowering plants during this period, 100 million years earlier than previously believed.

Darwin's Evolution Through Natural Selection Consistent With Cambrian Explosion

This image shows marine life during the Cambrian explosion (~520 million years ago). A giant Anomalocaris investigates a trilobite, while Opabinia looks on from the right and the "walking cactus" Diania crawls underneath. All of these creatures are related to living arthropods.
Credit: Katrina Kenny & Nobumichi Tamura

Scientists report that Charles Darwin's evolution through natural selection theory is consistent with the sudden diversity of life during the Cambrian explosion. Their study shows that a sustained accelerated rate of evolution over millions of years would have resulted in an increased rate of over five times; 100 million years of evolutionary change would have only took about 20 million years.

580 million years ago, living organisms were mostly simple cells that occasionally organized into colonies. The following 70 to 80 million years suddenly showed a diverse amount of life that included animals, phytoplankton, and calcimicrobes.

This period of the Earth's history is called the Cambrian explosion. During this period, the evolutionary rate of living organisms accelerated and the diversity of living organisms began to resemble that of organisms today.

Fossil records have shown the results and aftermath of the Cambrian explosion but the reason for it to happen and why it has not repeated again is still a mystery.

Discovery of Unknown Worm Fossil at Burgess Shale Hailed As Major Scientific Find

Undescribed species of a modern enteropneust (ptychoderid) worm. The proboscis is to the left. The total length of a relaxed and uncoiled animal is approximately 88 mm.
Credit: Photo: C.B. Cameron, Université de Montréal.

The discovery of fossils of previously unknown soft bodied worms at the Burgess Shale is being hailed as a significant find and offer a wider perspective on the diversity of life during the Cambrian period.

Shale is a clastic (composed of fragments) sedimentary rock that is fine grained and made up of mud. The mud in shale is composed of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite.

In Yoho National Park located in the Canadian Rockies of British Columbia is the fossil field known as the Burgess Shale. It contains some of the most important and significant fossil deposits dating back to the Middle Cambrian period, 505 million years ago. The rock unit is a black shale and crops out at a number of localities near the town of Field in Yoho National Park.

The rapid appearance of most major animal phyla in the fossil record accompanied by major diversification of organisms including animals, phytoplankton, and calcimicrobes made the Cambrian period an important point in the history of life on Earth. The period between 530 million and 550 million years ago is known as the Cambrian explosion due to the sudden diversity of life discovered living then.

Burgess Shale was discovered by Charles Walcott in 1909. And during the time of discovery up to the death of Walcott in 1927, some 65,000 specimens have been discovered already. Even after this, the fossil field has still yielded significant amounts of fossils that gave a glimpse of the diversity of life around 500 million years ago.