History of life forms

• What is the time frame for the history of life on Earth?

  Over 3.5 billion years ago to the present day
• What factors have shaped the development of life on Earth?

  Geological changes and climate changes
• What are the major geological changes that have affected life on Earth?

  • Mountain formation
  • Lowering of sea levels
• How does climate change relate to geological changes?

  Geological changes cause changes in climate, which alters habitats for life
• What is continental drift?


  The slow movement of the continents across the surface of the Earth
• What role did carbon dioxide levels play in climate change?

  Carbon dioxide levels were a significant factor in past climate changes
• What are stromatolites and their significance?

  Stromatolites changed the Earth's atmosphere by releasing oxygen
• How did the evolution of land plants affect carbon dioxide levels?

  Land plants used carbon dioxide for photosynthesis, decreasing its levels in the atmosphere
• What was the impact of increased oxygen levels during the Devonian period?

  Increased oxygen levels allowed the evolution of larger, more active animals
• What types of large animals evolved during the Devonian period?

  Giant dragonflies and large scorpions
• What was the effect of reduced carbon dioxide levels on Earth's climate?

  It led to a cooling of the Earth and the formation of glaciers
• How did the formation of glaciers during an ice age affect sea levels?

  It led to a drop in sea levels due to moisture being locked in glacial ice
• What happens to sea levels when glaciers melt at the end of an ice age?

  Sea levels rise and cover large land areas
• What fossil evidence indicates climate change in South Africa?

  Fossils of ammonites and bivalve mollusks from the Cretaceous period
• What did Phil Gingerich discover in the Sahara Desert related to climate change?

  Fossils of whales indicating the area was once covered by sea
• How did climate change contribute to evolution and extinction?

  Climate change led to the evolution of new species and the extinction of others
• What significant event occurred during the Cambrian period?

  The Cambrian explosion, where all phyla evolved in the sea
• What was the climate like at the beginning of the Cambrian period?


  The climate was cold, but it grew warmer over time
• What types of animals dominated the Cambrian seas?

  Invertebrates, particularly trilobites
• What are trilobites and why are they significant?

  Trilobites were abundant arthropods and among the first animals to have eyesight
• What was the first known chordate during the Cambrian period?

  Pikaia
• What are the defining characteristics of chordates?

  Chordates have a hollow nerve cord and a notochord at some stage of development
• What are the key characteristics of the Cambrian explosion?

  • All existing phyla evolved in the sea
  • Significant development of different body plans
  • Explosion of invertebrate life forms
• What type of algae dominated the Cambrian period?

  Simple, one-celled algae
• How did the shape of continents provide evidence for continental drift?

  The east coast of South America and the west coast of Africa fit together like a jigsaw puzzle
• What geological evidence supports continental drift?

  The mineral content and age of rocks in Brazil and Ghana are identical
• What fossil evidence supports the theory of continental drift?

  Fossil reptiles found in South Africa are also found in Brazil and Argentina
• What is the significance of the coelacanth in evolutionary biology?

  Coelacanths are considered a link between lobe-finned fish and land animals.
• How did coelacanths evolve from jawless fish?

  Coelacanths evolved from jawless fish approximately 390 million years ago.
• When was the first living coelacanth discovered?

  In 1938.
• What adaptation do lobe-finned fish like coelacanths have that allows them to move across the sea floor?

  They have fleshy bases supporting their fins, which are strong and edible.
• What is the significance of the internal organs of coelacanths in relation to amphibians?

  The internal organs of coelacanths are very similar to those of amphibians, supporting their evolutionary link.
• What is Archaeopteryx known for in evolutionary history?

  Archaeopteryx is known as the missing link between dinosaurs and birds.
• What are some physical characteristics of Archaeopteryx?

  It had a wingspan of about 50 cm, was about 30 cm long, and weighed between 300 and 500 g.
• How does the skeletal structure of Archaeopteryx compare to that of modern birds?

  Archaeopteryx had a skull with teeth and claws on its wings, unlike modern birds.
• What features of Archaeopteryx suggest it was part bird and part dinosaur?

  It had feathers, a long bony tail, and a skull with teeth.
• What is Thrinaxodon and when did it exist?

  Thrinaxodon was a mammal-like reptile that existed during the Triassic period, approximately 240 million years ago.
• What are some features of Thrinaxodon that suggest a link to mammals?

  Thrinaxodon had a lower jaw structure similar to mammals and a diaphragm for breathing.
• Why do scientists believe Thrinaxodon may have had fur?

  Because it had whisker-like pits on its skull, suggesting a protective covering of fur.
• How does the body temperature regulation of Thrinaxodon differ from that of reptiles?

  Thrinaxodon likely had internal body temperature regulation, unlike reptiles, which are ectothermic.