How Do Fossils Provide Evidence For Evolution

How Do Fossils Provide Evidence For Evolution? (2022)

The evidence for evolution is strong. There is an extensive and compelling body of evidence supporting it. Biologists can see the signature of modern and extinct species, from the smallest organisms to the most complex living systems. 

The book, On The Origin Of Species, which Charles Darwin created to determine our nature patterns, proves that we are constantly evolving. But, based on Darwinism, how do fossils provide evidence for evolution? Let’s find out!

Fossils provide solid evidence that organisms that have lived in the past are not the same extant organisms found today. The fossil record shows that the evolution of form has continued for millions of years. 

Some records of the very detailed fossils of animals that lived in the past have been recovered for the evolution of modern horses.

In North America, several transition fossils show the intermediate anatomical structures between their common ancestor to earlier and later forms. 

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The fossil record dates back to a dog-like common ancestor that lived around 55 million years ago. This led to the development of the first horse-like species around 42 million years ago. Though closely related, the anatomical features of these animals were changed due to the changing landscape and geographic distribution. 

Through DNA sequences, successive fossil shows the development of teeth shapes and foot and leg anatomy, with adaptations for escaping from predators, for instance, in species of Mesohippus discovered from 30 to 40 million years ago. 

Then, many species showed gains in size, such as Hipparion, which existed from 2 to 23 million years ago, and other organisms presented vestigial structures. In addition, the fossil record suggests several adaptive radiation within the very diverse lineage of horses, which is now reduced to only one genus, Equus, along with several new species. 

Why Fossils Are Important Evidence For Evolution?

Fossils provide essential information about the evolution and life forms that existed on Earth millions of years ago [1]. Also, the resulting fossil record tells life on Earth was once different from present day organisms. 

Fossils refer to preserved remains of plants and animals from the past. In fact, fossils range from 10,000 to over 3 billion years old. Due to the discovery of certain types of fossils, geologists recognized a geological timescale during the 19th century. Fossils vary in size, ranging from tiny organisms to gigantic, such as trees and dinosaurs.

4 Ways How Fossils Provide Evidence for Evolution

4 Ways How Fossils Provide Evidence for Evolution

1. Age of Fossil

A fossil’s age is determined by two methods: absolute dating and relative dating. With relative dating, researchers use comparative anatomy to compare the various characteristics of fossils to those of similar rocks and remains of known ages. Absolute dating is a method that uses radiometric dating to determine the age of a fossil. It involves measuring the decay of certain radioactive compounds within the fossil.

2. Fossil Record Incompleteness

The discovery of fossils represents a historical moment in the evolution of organisms. Unfortunately, many important groups and other organisms may never leave fossils behind due to the special conditions involved in their fossilization. 

Even if a species does leave fossils, humans will never find them because they are buried elsewhere and distributed worldwide. The figure of known species through the fossil record is meager, with less than 5% of the total number of known organisms.

3. The Fossil Record

Including both discovered and undiscovered fossils and their placements in certain rock strata (sedimentary layers) are what we call fossil records. The fossil record is regarded as one of the earliest sources of information regarding the evolution of life on Earth. 

So, during the 20th century, the development of methods enabled geologists to determine the age of various strata, which allowed them to collect more accurate data about successive fossils – including chitinous or calcareous exoskeletons. 

4. Category of Fossil

Fossils are the remains of organisms that lived once. They are the traces of previously living creatures that have been preserved. It is categorized into five finer aspects – body fossils, including internal and external molds, molecular fossils, trace fossils, carbon fossils, and pseudofossils [2].

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Body Portions That Can Be Fossilized

Chemofossils

Chemofossils contain organic compounds or proteins extracted from a body of rock. It is crucial in scientific research into well-preserved sedimentary rocks. For example, today’s waxy compounds found on leaves have been discovered in ancient rocks, showing the plant family’s presence and when these plants evolved. 

Trace Fossils

A record of biological activity that doesn’t include the preserved remains of an animal or plant are called trace fossils, like dinosaur footprints.

Unlike body fossils, which are remains of organisms’ bodies altered through chemical or mineral development, a trace fossil does not usually contain traces of living organisms.

Trace Fossils

Body Fossils

These are remains of an organism or animal that have been preserved in its original state. These can be molded or cast, like fossilized dinosaur skeletons and big bones, mammoths caught in ice, or insects trapped in amber.

Read: How Natural Selection Affects Evolution

FAQs

Fossil formation occurs due to chemical reaction, heat, and pressure that hardens the sediments, where the body of animals turns into sedimentary rock. The movement of the Earth’s crust and tectonic plates helps push the sedimentary rock back up into the higher ground. Once exposed, the fossils are then exposed again through erosion.

Once an organism has died, its remains need to be covered in sediment as part of the initial decay process. Once the minerals in the sediment have started to seep into the body parts of the dead organism, they can then be fossilized. Usually, the remains of hard-bodied organisms, such as skeletons, are the ones that get fossilized [3].

Finals Thoughts On Fossils Providing Evidence for Evolution

Fossil record extends the opportunity to study ancestral species, endemic species, and any other different species from the past. Fossil reflecting evolutionary history allows us to see how different organisms evolved on Earth. 

As geologists and paleontologists continuously discover and present a detailed fossil record, this further supports Charles Darwin’s theory of evolution, which believes that life forms gradually evolve over time, with the influence of genetic material, homologous structures,  and analogous structures. 

References: 

  1. https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book
  2. https://byjus.com/physics/types-of-fossils/
  3. https://www.nationalgeographic.org/encyclopedia/fossil/
Sarah Pace

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