week 4

Question 1

describe the evolution of posture and gait

Answer 1

• upright posture enables a switch from lateral undulation of the spinal column to dorsoventral undulation
• ribcage no longer restricted by locomotion from lateral undulation
• lumbar region modified: ribs are shortened to accommodate the new style of locomotion
• running becomes more efficient

Question 2

how to correct for bias

Answer 2

• subsampling methods
• simulations
• modelling approaches
• phylogenetic diversity methods

Question 3

describe basic subsampling

Answer 3

• borrowed from ecology
• enables us to compare the number of species in samples of different sizes
• standardise (randomly sample) to the smallest sample size, repeating to get an average results
• means a loss of some data
• doesn’t address all issues
• e.g. if sample A has 50 samples and B has 25, take 25 samples from A, count taxa, repeat

Question 4

describe advanced subsampling

Answer 4

• variety of advanced methods to account for different cases
• uses algorithms to also equate for changes in area through time

Question 5

describe simulations

Answer 5

• can develop approaches that provide a ‘null’ hypothesis to test the fossil record against
• can use data from the modern, entirely simulated data, or a combination
• possible to carry out on desktop equipment

Question 6

describe modelling

Answer 6

• allows us to use the known fossil record alongside relevant covariates to understand drivers and controls on diversity/preservation through time
• variety of approaches, simple linear models to machine learning algorithms
• can be used alongside outputs from other models

Question 7

what info can we use other than skeletons

Answer 7

• trace fossils e.g. footprints - tells us running speed and size of animal
• represents where the animal actually lived