Paleontological and Geological Evidence
What are fossils?
Fossils are remains, impressions, or traces of life forms that have been preserved in material such as ice, sediment, or amber.
What is relative dating?
Relative dating is the process of determining the relative order or chronology of past events.
Why is it important to use multiple secondary sources when evaluating evolutionary claims?
It is important to use multiple secondary sources when evaluating evolutionary claims in order to compare reliability and identity bias, as well as to strengthen the validity of conclusions.
What two types of factors initiate changes in ecosystems?
Broadly, abiotic and biotic factors initiate changes in ecosystems, causing organisms to adapt to selection pressures.
What is the difference between paleontological and geological evidence? Give an example of each.
Paleontological evidence refers to evidence of past life, whereas geological evidence refers to evidence from Earth's structures and formations (non-living).
An example of paleontological evidence is fossils.
An example of geological evidence is banded iron formations.
Other examples include the principles of stratigraphy, volcanic ash and paleosoils.
What is radiometric dating?
Radiometric dating is the process of determining the age of rocks or fossils from the decay of radioisotopes.
What impacts affected past the evolution of biota in past Australian ecosystems?
The evolution of biota in past Australian ecosystems is closely connected to the evolution of climate and the landmass's tectonic setting as it slowly drifted north. As the land became profoundly characterised by hot and dry conditions - affecting flora - a change in fauna occurred. Convergent evolution supports this change, illustrated through similarities in Australian marsupial mammals and North American eutherian mammals (both endure similar selection pressures).
What is ice core drilling and what does it tell scientists?
Ice core drilling is a scientific method used to study past ecosystems (particularly through the perspective of climate), conducted by extracting ice cores from polar ice sheets or glaciers. These ice cores provide valuable information about the Earth's climate history, encompassing temperature fluctuations, atmospheric composition, and greenhouse gas concentrations.
What does the presence of increased CO2 levels in ancient ice cores suggest?
Scientists utilise the method of ice core drilling to infer past gas compositions and thus past climates. Gas analysis tools, including mass spectrometry and gas chromatography, measure the composition of gases in small air bubbles secreted by layers of ice. Higher concentrations of CO₂ in these layers typically correspond to warmer periods in Earth's history, such as interglacial phases. This correlation aids in the confirmation of the link between greenhouse gas levels and global temperature fluctuations over geological time.
What is a sclerophyll plant and how has it adapted to dry conditions in Australia?
A sclerophyll plant is a type of plant that exhibits tough, leathery leaves with thick cuticles and sunken stomata. These physical attributes reduced water loss and allow survival in a dry environment characterised by nutrient-poor soils.
Why are stratigraphy and the Law of Superposition useful?
Stratigraphy is useful for singular rock formations, comparing the positions of rock strata that contain fossils. This process determines the comparative time scale of the occurrence of fossils.
The Law of Superposition states that each rock layer is older than the one above it, enabling paleontologists to chronologically organise the fossil record.
What is gas analysis and why is it useful?
Gas analysis is the process of identifying and quantifying specific gases within a mixed sample, or analysing a gas for purity or composition.
It is commonly used in ice core drilling (analysis of ice cores -> sample of ice removed from an ice sheet that contain clues to past climates and ecosystems), which is crucial for reconstructing past ecosystems.
List a main origin of Australian flora + a main origin of Australian fauna.
Fauna - original residents (those that were on the continent when it split from Gondwana); Asian immigrants that arrived when sea levels were low; Those introduced by immigrant traders or late arrival Aboriginals; Those introduced by European immigrants.
What evidence do Aboriginal rock paintings provide to scientists?
Name three examples of substances used in radiometric dating + three examples of substances assessed in gas analysis.
Radiometric dating - carbon-14 (radiocarbon), uranium-lead (U-Pb), and rubidium-strontium (Rb-Sr).
Gas analysis - oxygen (O2), carbon dioxide (CO2) and carbon monoxide (CO).
The diprotodon optatum was the largest known living Australian marsupial, becoming extinct due to pleistocene droughts (extended dry periods which culminated in habitat loss and reduced food avaliability and survival).
The Riversleigh playtpus was a large, spoon-billed platypus from the Riversleigh area of northern Australia, becoming extinct due to dry conditions and the evolutionary disadvantage of functional molar teeth (toothless platypus species implemented more effective feeding strategies, suggesting competition).
Lastly, the thylacoleo carnifex was the largest known mammalian carnivore to live in Australia, becoming extinct due to major ecosystem shifts (e.g. Pleistocene epoch).