Lesson 4

• These are remains of ancient organisms trapped in rocks, tar pits, frozen in ice or embedded in amber.


  Fossils
• Fossils can be trapped in:

  • Rocks
  • Tar Pits
  • Frozen in Ice
  • Embedded in Amber
• The activities and behavior of ancient life forms also left behind fossil traces which scientists can study.
• The records found in the rocks/fossils show a gradual evolutionary descent from simpler to more complex life forms
• Paleontologists use the fossils found in rocks to track the evolutionary history of many organisms.
• It is the scientific study of ancient life forms based on fossil evidence.


  Paleontology
• A paleontologist studies the fossils found in rocks to reconstruct the past environment and climate conditions that existed when these organisms lived.
• Paleontologists have discovered that most of the major groups of animals now existing had already appeared by the end of the Cambrian period (500 million years ago).
• The study of fossils provides information about how different species evolved over time, including their physical characteristics, behaviors, and relationships with other living things.
• Fossils are formed through processes such as petrification, carbonization, replacement, compression, and mummification.
• Fossils are formed when an animal or plant dies and becomes buried under sediment such as sand or mud. Over time, the sediment hardens into rock, preserving the remains of the organism within it.
• Paleontologists analyze the fossils they find to understand how different species interacted with one another and how they adapted to changing environments.
• By studying the distribution and abundance of fossils, scientists can infer changes in the Earth's climate and geography throughout history.
• Fossils can be used to estimate the age of rocks and understand the sequence of events that occurred during the formation of the planet.
• It allows us to make predictions about future environmental conditions based on historical data.
• Studying fossils provides insight into the effects of human activities on the environment and informs conservation efforts aimed at protecting endangered species.
• The process by which fossils form is called fossilization.
• These are structures with the same set of bones that presumably evolved from a common ancestor.

  Homologous structures
• They appear different and may have varied functions.

  Homologous Structures
• These are structures that perform the same function but have very different embryological development or set of structures like bones. 


  ANALOGOUS STRUCTURES
• These are structures or attributes that have lost most of its ancestral function in more recent species.


  VESTIGIAL STRUCTURES
• It is a term commonly used when referring to a body part that has become reduced in size from its original form or has lost its function due to evolutionary change.


  Vestigial
• Example of vestigials are Wisdom Teeth which are vestigial third molars that most people are very familiar with.
• Evolutionists believed that our ancestors used wisdom teeth to grind up the hard seeds and nuts that were once part of the human diet.
• It is the study of the development of an organism from an embryo to its adult form.

  Embryology
• Common structures are shared in the embryo stage and disappear by the time the embryo reaches the juvenile or adult form.
• Many organisms have similar molecules of life (RNA, DNA, proteins) that suggest descent from a common ancestor with modifications.
• The near universality of the genetic code reflects an evidence of common ancestry and relatedness and can be inferred from the similarities in the DNA sequences between and among organisms.


  Evidence from Molecular Biology
• It is the study of geographical distribution of fossils and living organisms.

  Geography
• Organisms usually arise in areas where similar forms already exist.


  Evidence from Biogeography/Geographic Distribution
• Similar organisms may also be found in different locations which could mean that the two places were previously connected.


  Evidence from Biogeography/Geographic Distribution
• Living things share some biomolecules, such as DNA, RNA, and proteins which may be used to prove relationships.
• The building blocks of these chemicals may be analyzed to show similarities and differences among organisms.
• The more similarities, the closer the relationships.
• 5 Evidence of Evolution

  1. Evidence from Paleontology/Fossil Records
  2. Evidence from Comparative Anatomy /Structures
  3. Evidence from Embryology
  4. Evidence from Molecular Biology
  5. Evidence from Biogeography/Geographic Distribution