The 'plant' is a kingdom of life forms, which is an essential part in the ecology. It plays an important role in maintaining life forms on the earth. Without this kingdom, other living organisms may have gone extinct. Fossils of plants are the preserved body parts of a plant, belonging to millions of years ago. Mostly the leaves are acquired as the fossil remains, sometimes in a fragmented condition and sometimes as a whole leaf. The other parts like flowers, ferns, cones, bark section, petrified wood and fronds are also seen as the fossils remains. Like plants, plant fossils are also very important in the creation of nature, like the coal deposits in the earth's crust and the oil deposits that owe their existence to the remains of the plant fossils.
The first fossil of plants discovered, belongs to the Silurian and Paleozoic era. Several different types of fossils were derived from the sedimentary rock deposits like Rhynie Chert near the Rhynie village in Scotland. In the Late Devonian era, macro-fossils of plants were obtained, which included fronds, roots and tree trunks. The coal deposits present in Europe and North America consist of the vast amount of fossils that include Arborescent lycopods (treelike vascular plants), Seed ferns, Conifers and innumerable herbaceous plants. The flowering plant genus Angiosperms is believed to have emerged during the Mesozoic period and the pollens and leaf fossils were obtained, which belonged to the Cretaceous era around130 million years ago..
The fossils of plants are never acquired in the form of a whole plant, but only as fragmented and bits of plant body parts like,
Leaves-: The most common part of the plant found as fossil are the leaves. The leaves of the extinct species look very unique, whereas the others have the same shape and structure of the ones found in our surroundings. The plants still growing today in our surroundings have also been collected as fossils and the list includes Willows, Sycamores, Oaks, Poplars, Maples and Gingos. The length of the fossil leaves is found around 2 to 4 inches, but some exceptional leaves are also found about 6 feet in length. The fossil leaves obtained with intact veins and stems, are highly prized among the fossil collectors and investors.
Ferns-: The Ferns are abundantly found among the plant fossils, and can be easily recognized. But the ferns found as fossils are actually the Seed ferns, an extinct plant belonging to gymnosperm genus. This plant resembles the original fern plant found in our surroundings but instead of spores, the Seed ferns reproduce by seeds. It is believed that the forest floors and the swampy areas in the Pennsylvanian era were covered with thick and dense fern plants, which later turned into a thick layer of fossil all over the forest. It is believed that these fossils underwent changes over many million years, and was transformed into coal deposits found in West Virginia and Pennsylvania regions.
Cones and Seeds-: The Seeds and Cones of the plants are also found as fossils occasionally. The part of the plant belonging to the gymnosperm genus, which bears the seeds are known as cones. The seeds of this genus are not found in the ovary, but are seen nakedly spread on the sphrophyll's (cone) surface. Usually complete cones or seeds are difficult to obtain, but there are specific locations, where the fossils look new and freshly obtained from the tree.
Tree Bark-: The fossilized part of the plant also consists of tree barks or trunks that grow in the forest and eventually fall over the rock present in the forest. This bark often leaves the imprints forever on the rocks, which clearly shows the shape, length and design. Some fossilized tree barks are very long, whereas some are just hand sized fossil remains. The design over the bark is also unique, and different from the ones found in the modern world. It possesses scale and diamond shapes, all over the bark.
Flowers-: Due to its characteristics, the least commonly found fossil part of a plant are the flowers,. The flowers are so delicate and often seen only a few weeks in the whole year, which is why, the fossils are rare. But exceptional flower fossils are rarely found with intact color and shape along with preserved stamens and petals, which are also highly prized by the collectors.
Petrified Wood-: This part of the plant is also very commonly found as a fossil. In the ancient eras, the whole tree or the whole forest becomes fossilized by getting buried under the sediments. During the "Petrification" procedure, the cellular structure remains the same, but the inside materials of the wood get replaced by the minerals found under the crust, mostly silica. Thus, it turns into a rock structure with variant colors, acquired from the traces of minerals that replaced the wood. Different colors like yellow, red, green and orange are found in the petrified fossils.
The fossils of plants are of two types, the one that has gone extinct at the end of prehistoric eras and the other that is still found with some minute changes, in the surrounding environments; this type is called the living fossils. Certain fossils that has gone extinct, and they are-:
This plant belongs to the Araucariaceae family and was a coniferous tree, found in the Patagonia regions of Argentina. The forest, densely populated with this plant was affected by the volcanic eruption, about 160 million years before and thus got extinct.
This flowering species of plant belonging to Trochodendraceae family have gone extinct and the fossilized leaves of this plant were found in the Klondike Mountain Formation areas, Washington. The fossils are believed to be from the Eocene Ypresian era.
This plant belongs to the Archaeopteridaceae family and has a tree like structure. Its leaves are similar to that of the fern. Its fossils belong between the early Devonian period to the end of Carboniferous era, which means around 323 million years ago.
The fossils of Protosalvinia belong to the Early Devonian period and it is classified into Protosalvinia genus. Its habitat was along the shoreline.
This plant was the largest genus of the Seed fern order. The fossils are believed to be from the Permian period, belonging to around 298 million years ago.
This flowering plant belongs to the Lotus family. It is an extinct plant species which have fossils dating back to Ypresian age and was obtained from the western part of North Dakota, USA.
The other similar plants that have gone extinct, leaving the fossilized remains are
- Hymenaea protera
- Peltandra Primaeva