Paleontology Flashcards
What is continental drift?
The gradual movement of the continents across the earth’s surface through geological time.
This movement is evidenced by scars on the ocean floor.
Who introduced the Theory of Continental Drift and when?
Alfred Wegener introduced the theory in 1912.
The theory gained wider acceptance in the 1960s.
What was the revolutionary aspect of the Theory of Continental Drift?
It changed the understanding of species and their distribution globally.
The theory explained the former connection of continents and species.
What is Pangaea?
A supercontinent that existed approximately 335 million years ago and began to break apart about 175 million years ago.
Pangaea was centered on the Equator.
What geological mechanism explains continental drift?
Plate tectonics.
This mechanism describes the movement of the plates below Earth’s surface.
During which eras did Pangaea exist?
Late Paleozoic and early Mesozoic eras.
Pangaea was surrounded by the super-ocean Panthalassa.
What was Gondwana?
A large landmass that existed from 450 to 120 million years ago.
Gondwana was part of Pangaea before splitting from Laurasia.
List the continents included in Gondwana.
- South America
- Africa
- India
- Antarctica
- Australia
Gondwana started to split up around 150 million years ago.
True or False: Pangaea was the first supercontinent to exist.
False.
Pangaea is the most recent supercontinent.
How does understanding continental drift contribute to our knowledge of evolution?
It reveals how species were once connected on the same landmass but later became isolated.
This isolation led to the evolution of distinct species and ecosystems.
What is biogeography?
The study of the distribution of species and ecosystems in geographic space and through geological time.
Biogeography helps understand how living organisms have evolved to adapt to different environments.
How does continental drift relate to biogeography?
It helps understand the distribution of living organisms and how they evolved due to geological events.
Geological events influenced the migration and diversification of species.
What is the significance of studying biogeography?
It provides knowledge for understanding the history of life on Earth.
Understanding past geological events is crucial for tracing species evolution.
What are Ratite birds?
Flightless birds descended from a single ancestor that lived across Gondwana.
Ratites evolved independently after the separation of land masses.
Why are Ratite birds only found on southern continents?
Because they evolved independently after the land masses of Gondwana separated.
Their distribution is a result of historical geological events.
What anatomical feature distinguishes Ratite birds from other flightless birds?
They have no keel on their sternum.
The lack of a keel prevents them from flying even if they had suitable wings.
What are fossils?
Remains, impressions, or traces of ancient life forms preserved in the Earth’s crust.
Fossils provide a direct record of ancient life and evolution.
What are the different types of fossils?
True form, trace, mould, and cast fossils.
Each type provides different insights into ancient life.
What are true form fossils?
Fossils made of an actual plant or animal, preserved through permineralisation.
True form fossils consist of hard parts like bones or stems.
What is permineralisation?
The process where organic compounds are replaced molecule by molecule with inorganic minerals.
This process can lead to the petrification of organisms.
What are trace fossils?
Fossils that record the behaviors and movements of animals, such as footprints and nests.
They provide insights into the lifestyle of ancient organisms.
How is a mould fossil formed?
By leaving a hollow impression of a plant or animal in sediment.
The surrounding sediment hardens around the organism before decomposition.
What is a cast fossil?
A natural occurring replica formed when sediment fills in a hollow mould fossil.
Cast fossils provide a three-dimensional representation of the original organism.
What are the four key conditions necessary for fossil formation?
- The organism must die in a suitable location with little oxygen
- The carcass must be rapidly buried
- Permineralisation must occur over time
- The fossil must be exposed by erosion and discovered before it erodes
These conditions prevent decomposition and allow for the preservation of the organism as a fossil.
What is the purpose of dating fossils?
To place absolute dates on the geological record and understand the history of life on Earth
This helps scientists discover when different species lived and provides evidence for evolution.
What does relative dating of fossils rely on?
The order of sedimentary deposition
Older fossils are typically found deeper in sedimentary rocks.
What are index fossils?
Organisms that were widespread, common, and lived during a specific time
They are used to compare locations and calibrate different sedimentary layers.
What is radiometric dating?
A type of absolute dating that uses radioactivity to determine the age of rock layers or fossils
It involves measuring the decay of unstable elements into stable ones.
What is half-life in the context of radioactive isotopes?
The time it takes for half the mass of a radioactive element to decay into its decay product
Different isotopes have different half-lives, making them useful for various dating applications.
What are missing links in paleontology?
Organisms that show intermediate characteristics between old and new groups
They are hypothesized organisms that can help fill gaps in the evolutionary record.
What are transitional forms?
Fossils of previously hypothesized missing links that provide evidence for evolution
Their discovery is often a significant event in the scientific community.
What evidence does the discovery of Ambulocetus provide?
Understanding the evolution of cetaceans (dolphins and whales)
Ambulocetus is considered a significant transitional form in whale evolution.
What does the discovery of Archaeoptery contribute to?
Understanding the evolution of aves (birds)
Archaeopteryx was a dinosaur with bird-like features, bridging the gap between reptiles and birds.
What is Thrinaxodon?
A tetrapod with both reptile and mammal-like features
Thrinaxodon is significant in the study of mammal evolution.
What are tetrapods?
Vertebrates with four limbs, including amphibians, reptiles, birds, and mammals
Tetrapods evolved from a common ancestor that was a fish with lobed fins.
What are ‘living fossils’?
Organisms belonging to groups previously known only from the fossil record
They resemble ancient fossil specimens and are likely their living descendants.
What characteristics do coelacanths display?
Primitive tetrapod-like characteristics, specifically lobed fins
Coelacanths were known only from the fossil record until a living specimen was found in 1938.
When were coelacanths known only from the fossil record?
360-65 million years ago
The first living specimen was caught in 1938.
What was Ginkgo once known for in the fossil record?
A globally distributed group of plants represented by many species
Ginkgo is notable for its historical distribution.
What is the significance of fossil tourism in South Africa?
An important source of income and employment in fossil-rich areas
It attracts both international paleontologists and tourists.
What is the Cradle of Humankind?
A World Heritage Site in Gauteng, South Africa, known for significant fossil discoveries
It includes sites like Sterkfontein, Swartkrans, and Kromdraai.
Name two significant fossils found in the Cradle of Humankind.
- Mrs Ples
- Little Foot
- Karabo Child (2008)
These fossils have contributed greatly to our understanding of human origins.
What is ‘Maropeng’?
The Tswana word for ‘origins’ and a tourist centre near the Cradle of Humankind
It plays a role in educating visitors about human evolution.
Name three other areas in South Africa rich in fossils.
- Langebaan
- Border Cave
- Karoo area
These areas also attract tourists and contribute to local economies.
How can local South Africans benefit from fossil tourism?
By working as tour guides, hotel staff, game rangers, drivers, curio sellers, etc.
It is essential for local communities to view these sites as economic opportunities.
True or False: Fossil sites are only of academic interest and have no relevance to local communities.
False
Local communities can find employment and income through fossil tourism.
