Living Fossil


Introduction

Living fossils might be living, but they do not retain the primitive features of their ancestors. Due to the prolonged adaptation, the behavior and survival capacity of living fossils is much more advanced than their ancestors. There are various schools of thought provided by different scientists, that living fossils have many specialized characters like exhibiting non-adaptive radiation, i.e., having low rates of ecological and phenotypic evolution thereby giving them a longer staying power.

There are immense educational implications for living fossils in excavating Earth’s evolutionary and biblical records. An organism is referred as “living fossil” if the organism resembles the fossil representative and share the same taxonomic level — usually same genus or species group.

Different Types of Fossil

According to the nature of fossilisation, fossils may be of the following types −

Petrifaction

  • Petrifaction is the process of filling hard water in the cavities existing in organisms.

  • It is considered the most common form of fossilisation for both animals and large plants.

  • Petrified dinosaur bones have led scientists to reveal detailed histological studies of some extinct reptiles.

  • Petrified wood exemplified the field of Paleobotany as well as serving as an artistic and inspiration manifestation.

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Cast or Incrustation

  • A cast fossil mostly preserves the impression of the hard parts of any living organism. For example, it can be an exoskeleton part.

  • Sandstones mostly represent cast fossils and other porous rocks as well. As the rate of decaying process is slower in hard parts than the softer tissues, they have a high probability of leaving cast fossils.

  • Soft tissues have a higher rate of decaying process.

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Impression

  • Any organic part of a plant or animal part falling on semi cliff clay easily creates an impression on its surface.

  • In course of time this impression becomes permanent when the clay turns into stone. Such impressions are often of a darker colour than the surface of the rock below because it very often retains some of the organic material.

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Compression

  • Compression can be considered as a sub type of impression, where the organism gets impacted and petrified to a greater extent.

  • The great pressure under which fossilisation takes place flattens out all around or solid organs so that what remains in the fossil is usually a carbonaceous film.

  • Good compressions have led to swelling out the organ by some chemical treatments so that some details become visible.

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Rocks and Minerals of Organic Age

  • Any object which might have connection with ancient organisms is considered as a fossil. A stone showing the footprint of an animal or a trail of a worm is a fossil.

  • Gums of ancient resinous, coniferous trees are found in fossilised forms as amber which is of great importance and commercial value.

Examples of Living Fossils

For example, Amami Rabbit, which we have mentioned in the table below, is endemic to Japan. Hence following are some speculations about them are -

  • Evolution does not happen equally in all respects with all organisms.

  • Living fossils are an answer to the question why some species haven’t yet changed.

  • Finally, it can be concluded that they are widespread and diverse individuals with existing properties of their ancestors and restricted to specific geographical areas.

Examples of Living Fossils Characteristics of Living Fossils
Aardvark (Orycteropus Afer) The aardvark, also known as the African pig, is basically an ant-eater and are found in various parts of Sub-Saharan Africa.
Amami Rabbit (Pentalagus Furnessi) The Amami rabbit (Ryukyu) is primitive with dark-furred body. Mostly found in the Amami Oshima and Toku-no-shima Islands of Japan.
Elephant Shrew (Macroscelidea) Elephant shrews are small, four-legged insectivorous mammals endemic to Africa. The name “Elephant” comes from the inconspicuous resemblance of its long nose and the trunk of an elephant. Some of the other names they bear are- jumping shrews or sengis from the African Bantu languages.
Red Panda (Ailurus Fulgens) The red panda, also known as the lesser panda, red bearcat or the red cat-bear, are mostly confined to the Himalayas and parts of China. There are only less than 10000 Red pandas now, thereby making their place under endangered species.
Ginkgo biloba The family of Ginkgoaceae have been living on Earth for 270 million years. Sixty-five million years ago they began to decline, and only the Ginkgo biloba species in some areas of China persisted. Currently the oldest specimens have been around for nearly 3,500 years.

Conclusion

  • Living fossils might be living, but they do not retain the primitive features of their ancestors.

  • There are five different types of Fossils available.

  • Petrification, Cast, impression, compression, rocks or minerals of organic age are five different types of fossils.

  • Petrifaction is the process of filling hard water in the cavities existing in the organisms.

  • A cast fossil mostly preserves the impression of the hard parts of any living organism.

  • Impression is formed when an organism or its parts come in contact with soft clay.

  • Living fossils are not that different from normal fossils, they still exist and some of the lineages have about 50 species living which were once declared to be a fossil.

FAQs

Q1. How can a Fossil be Living?

Ans. The species were earlier declared to be dead or fossil but later on it was found that only one species of that lineage still exist. Example − Ginkgo biloba.

Q2. Can fossils contain DNA?

Ans. Yes, fossil DNA is a very important source of information of the extinct species. The fossil DNA has led to the discovery of Dinosaurs.

Q3. Do living fossils evolve?

Ans. Not all aspects of an organism change at the same rate over millions of years. In most living fossils, major physical features have changed very little over long stretches of time. But evolution is still occurring! The lack (or very slow rate) of change during evolution can be as interesting as change itself. It can take more than 1000 years.

Q4. Fossils can be of only plants or can Animals or Insects turn in to fossils as well?

Ans. Any dead organism can turn into a fossil with time. It is a myth that fossils can be of plants only. Fossils can be of any living organism existing on the Earth.

Q5. Do Human fossils exist?

Ans. No, till date there is no existence of Human Fossil. But yes Egyptian mummies can represent that.

Updated on: 29-Dec-2022

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