Week 4 - Paleobiogeography Flashcards
What is palaeobiogeography?
The study of the geographic distribution of ancient organisms and the factors that influenced their movement and evolution.
How can fossil distributions help reconstruct past environments?
By analysing where certain fossils are found, scientists can infer past climate conditions, ocean currents, and continental positions.
Why were Cambrian and Ordovician fossil assemblages different in North America and Europe?
These regions were separated by the Iapetus Ocean, preventing species from mixing.
How did the closure of the Iapetus Ocean affect fossil distributions?
It led to an increase in species similarity between North America and Europe as landmasses merged.
How does the presence of the same fossil species on multiple continents support plate tectonics?
It suggests that continents were once connected, allowing species to spread before drifting apart.
How do diversity indices help in reconstructing past environments?
They provide insights into biodiversity changes due to climate shifts, continental drift, and ocean circulation changes.
What role do similarity indices play in studying ancient biogeography?
They help determine if fossil assemblages from different locations were once part of the same ecosystem or separated by barriers like oceans.
How was the closure of the Iapetus Ocean identified using palaeobiogeography?
By comparing fossil taxa across different regions and identifying increasing similarities as continents moved closer together.
What is species richness (S) in palaeontology?
The number of different taxa (species, genera, families, etc.) in a given sample population.
What does Simpson’s Index of Dominance (D) measure?
The probability that two randomly selected individuals from a sample belong to the same species.
What is Simpsons Diversity Index?
Inverse of Index of Dominance showing the biodiversity.
What is evenness in a community?
The degree to which individuals are spread evenly across species in a sample. High evenness means no species dominates significantly.
What is the Jaccard Similarity Index used for?
Measures similarity between two sample sets based on shared taxa.
What is a limitation of the Jaccard Index?
It ignores shared absences and can be skewed when one sample is much larger than the other.
What is the Dice Coefficient (or Dice Similarity Index)?
A measure that gives more weight to shared species compared to the Jaccard Index.
What is the Simpson’s Coefficient of Similarity, and when is it useful?
It measures the proportion of shared taxa in relation to the smaller sample size, making it more robust for incomplete sampling.
