Key Characteristics and Famous Living Fossil Examples
Fossils are remnants of living beings that survived for a long period of time. These form evidence for the evolution of all civilizations. Living fossils are the ones that are used to study and describe the similarities and differences between the present and the past. This means that, through Living Fossils, you can portray a relationship between the living organisms and the fossils of extinct specimens.
What is a Fossil?
Fossils are the parts of living things that cannot be degraded over time, so they remain as traces in the environment. These naturally get buried in rocks and are preserved in the Earth’s crust. The word "fossil" comes from the Latin word "fossus," which means "dug up." These fossils are very helpful in studying organisms that are not actually present in the environment in the present day. Fossils may include any remnants of living organisms such as hair, imprints of animals on stones, shells, bones, coal, exoskeletons, petrified wood, and DNA remnants.
Different Types of Fossils
Fossils can be broadly divided into two categories:
One is the actual body parts of the organism that are fossilised over time. This can include bones, claws, teeth, skin, embryos, etc.
The other types are fossilised traces, which include the traces left by these organisms and cannot be considered actual body parts. These are also called ichno-fossils and can include footprints, dung, nests, or tooth marks. These traces can be useful in recording and tracking the movements and behaviours of these living organisms.
There are Six Different Types of Fossils, as Described Below:
Direct Fossils: When fossils are formed from the burial of an ancient living organism, their remains in the form of skeletons get reserved due to sedimentation. This type of fossil is called a direct fossil.
Ichno-Fossils: Fossils that are preserved in the form of traces such as nests, footprints, and faeces of ancient living organisms are called Ichnofossils. These fossils are not the actual body parts of the organism but only traces.
Chemo-Fossils: The fossils made by the chemicals left by the earlier life forms are known as chemo-fossils. These are the biological remnants or signals that can be traced to the past.
Resin Fossils: Fossils made up of amber with organisms trapped inside them are known as resin fossils. They have been preserved in these resins or ambers for millions of years and can be formed in the form of bacteria, fungi, or insects.
Living Fossils: These are fossils that have remnants of organisms that have only been identified through fossil records. These are essential for studying evolution and forming a tie between the present and the past. It is a term used for formerly undiscovered life forms.
Body Fossils: These are the fossils that are found in the hard parts of the living organism. This may include bones, claws, and teeth.
What is a Living Fossil?
Living fossils are the remnants of organisms that have been identified through fossil records only. These are essential for studying evolution, and they form a tie between the present and the past. The name “living fossils” is used for formerly undiscovered life forms. By assessing living fossils, a common descent for various living species can be pinpointed and studied. This can be done by comparing the various similarities and differences between the present living and fossil creatures.
According to Charles Darwin’s theory of evolution, all living fossils have evolved in some way or the other and are existing in some form. Changing ecosystems, increasing and falling temperatures and other changes in air composition and circumstances have all forced living species to adapt.
These organisms have adapted to their environmental restrictions, reaching a peak of competence in surroundings that consistently reinforce certain physicality. Since certain fossils reveal no similar traits, it is clear that the species existed. These extinct animals serve as a stark warning to a world that is rapidly losing other live species.
Living Fossil Examples
The dome of the examples of living fossils is given below, with a division of organisms according to the number of cells they bear.
Unicellular Organisms- Bacteria, Algae, and Protozoa.
Unicellular organisms are the earliest living things that were present as life forms on this planet. These include bacteria, algae, cyanobacteria, etc. These are organisms that carry out complex chemical processes and can survive the harshest environments. Cyanobacteria is the oldest living fossil and emerged as early as 3.5 billion years ago. These bacteria are still the most successful group of organisms present on Earth, and so their study can provide us with the most ancient records of life that were present on this planet.
Multicellular Organisms – Animals and Plants.
Single-celled organisms developed into multicellular organisms and can be studied as a course of evolution as well.
The comb jelly, which is a multicellular organism, first emerged 700 million years ago and is older than most rock fossils present. They have been useful in studying evolution and forming a trajectory of development. Another example of a living fossil animal is the horseshoe crabs. Their existence is dated back to 450 million years ago and they are known to resemble Crustaceans.
According to the new discoveries, Wollemi pine is known as the most popular living fossil plant or tree and is around 200 million years old. It is found that the same species as this tree is found in Australia.
Conclusion
This article gives an insight into the mesmerizing world of living fossils, their examples, and the different names of living fossils. It also talks about different types of living fossils and how they are made. These are made of both unicellular and multicellular organisms.
FAQs on What Are Living Fossils?
1. What is a living fossil, and can you provide some examples?
A living fossil is an existing species that closely resembles its ancestral species known only from the fossil record. These organisms have remained morphologically almost unchanged over millions of years, showing a very slow rate of evolution. They provide a unique glimpse into ancient life forms. Key examples include:
- Animals: The Coelacanth (fish), Limulus (Horseshoe Crab), and Nautilus (cephalopod).
- Plants: Ginkgo biloba (maidenhair tree) and Cycads.
2. Why is the Horseshoe Crab (Limulus) often cited as a classic example of a living fossil?
The Horseshoe Crab, Limulus, is considered a classic living fossil because its basic body plan has remained remarkably consistent for over 450 million years. Fossil records show that its ancient ancestors are almost identical to the species alive today. Despite its name, it is not a true crab but is more closely related to spiders and scorpions. Its survival through multiple mass extinctions with minimal morphological change makes it a prime subject for studying evolutionary stasis.
3. How is a 'living fossil' different from a regular fossil?
The key difference lies in what they represent. A living fossil is a currently living, or extant, organism that belongs to a lineage with a deep fossil history and has shown very little physical change over time. In contrast, a regular fossil refers to the preserved remains, impressions, or traces of organisms that are now extinct. So, a living fossil is a living being, while a fossil is preserved evidence of past life.
4. What is the evolutionary importance of studying living fossils?
Studying living fossils is crucial for understanding evolution for several reasons:
- Understanding Evolutionary Rates: They are excellent models for studying bradytely, or an exceptionally slow rate of evolution, contrasting with species that evolve rapidly.
- Validating Phylogenies: They help biologists validate evolutionary trees and relationships between different groups of organisms by providing a living link to ancient lineages.
- Insights into Past Environments: Their physiology and habitat can offer clues about the conditions of ancient ecosystems in which their ancestors thrived.
- Filling Gaps: Discoveries like the Coelacanth helped fill a significant gap in the fossil record, confirming the existence of lobe-finned fishes once thought to be long extinct.
5. Are there any examples of living fossils in the plant kingdom?
Yes, the plant kingdom has some of the most famous living fossils. The most prominent example is Ginkgo biloba, also known as the maidenhair tree. This species is the only surviving member of a division of plants, Ginkgophyta, that flourished during the age of dinosaurs. Another significant example is the Cycad, a group of seed plants that also have ancient origins dating back to the Permian period, over 280 million years ago.
6. Does the existence of living fossils mean that evolution has stopped for these species?
This is a common misconception. The term 'living fossil' refers primarily to morphological stasis, meaning the organism's physical form has not changed significantly. However, evolution has not stopped. These species continue to evolve at the molecular level, accumulating changes in their DNA over time. Their slow physical evolution is often attributed to a stable environment and a successful, generalized body plan that doesn't require significant adaptation.
7. Which fish is famously known as a living fossil and why was its discovery so significant?
The Coelacanth is the fish famously known as a living fossil. It belongs to a group of lobe-finned fishes that were believed to have gone extinct around 66 million years ago, along with the dinosaurs. Its rediscovery in 1938 off the coast of South Africa was a monumental event in biology. It was significant because it provided a living example of a lineage thought to be a close relative of the ancestors of tetrapods (four-limbed vertebrates, including humans).
