Evidences for Evolution

Study Notes

Evidences for Evolution

Classification, fossils, anatomy, chemical/molecular similarities, physiology, embryology, and geographic distribution of organisms are all evidences that support evolution.

Fossil Record

The age of fossils and rocks is determined using radioactive elements such as carbon, fluorine, and uranium.
The fossil record reveals that living organisms change gradually and transform from one form to another over millions of years.
The appearance of fossils occurs according to a regular order, with vertebrates appearing in the following order: jawless fish, amphibians, reptiles, birds, and mammals.
Non-vascular plants preceded vascular plants in existence.

Fossil Record as Evidence of Evolution

Fossils provide a record of ancient life and give information about the evolution of living organisms across the eras.
Fossils provide a complete picture of past life and are conclusive material evidence of evolution.
The remains and traces of organisms found in sedimentary rocks give an indisputable record of past changes over long periods of time.
Extinct species have been recorded as having transitional characteristics between the main groups of living organisms, confirming that species are not fixed, but can develop into other species over time.

Basilosaurus: A Fossil Evidence of Evolution

Basilosaurus is a fossil that supports the theory of evolution, with a mix of features showing it as a transitional form between land-dwelling mammals and fully aquatic whales.
Basilosaurus lived during the Eocene epoch (around 41.3 to 33.9 million years ago) and had a long, serpentine body with well-developed hind limbs.
These limbs were likely used for swimming but were not as functional for land movement as those of its ancestors.

Basilosaurus: Transitional Anatomy and Descent with Modification

Basilosaurus's transitional anatomy shows a mix of features, with a streamlined body for aquatic life and vestigial hind limbs.
Scientists believe Basilosaurus descended from a group of terrestrial carnivores called Mesonychids, with the presence of hind limbs pointing to this terrestrial ancestry.
Over time, these limbs became less important as Basilosaurus adapted to a fully aquatic lifestyle, demonstrating a gradual modification of a trait over generations.

Basilosaurus: Fossil Record Progression and Loss of Function

Fossils of other early whales like Pakicetus and Ambulocetus show an even stronger link to land mammals with well-developed limbs.
These fossils, along with Basilosaurus, depict a gradual shift in anatomy towards a fully aquatic existence in whales.
The presence of vestigial hind limbs in Basilosaurus showcases the concept of vestigial structures, which are organs or parts that have lost their original function but persist in a reduced form due to their evolutionary history.

Description

Explore the various evidences that support the theory of evolution, including classification, fossils, anatomy, and more. Learn how scientists use radioactive elements to determine the age of fossils and rocks.