Penetrative track morphology and sediment parameters: subsurface layers are robust to changes in substrate properties

Area of Science:

• Paleontology
• Geology
• Computational Science

Background:

• Track morphology is influenced by foot anatomy, motion, and sediment properties.
• Penetrative tracks offer valuable insights into foot motion due to enhanced foot-sediment interaction.
• Subsurface track morphology is crucial for accurate motion recovery.

Purpose of the Study:

• To investigate the influence of sediment consistency on subsurface track morphology.
• To compare the robustness of surface versus subsurface track morphology to sediment variations.
• To assess the reliability of motion reconstructions from penetrative tracks.

Main Methods:

• Utilized discrete element method (DEM) simulations.
• Modeled two scenarios: a vertically indenting cylinder and a dynamic theropod-like foot.
• Systematically varied sediment friction and cohesion to observe effects on track morphology.

Main Results:

• Increased sediment friction led to more pronounced displacement rims.
• Higher sediment cohesion resulted in tracks remaining open and resisting infilling.
• Low cohesion caused surface tracks to deviate significantly from the actual foot morphology.
• Subsurface track morphologies demonstrated greater resilience to changes in sediment properties compared to surface tracks.

Conclusions:

• Sediment behavior substantially alters surface track morphology but has a limited effect on subsurface morphology.
• Penetrative tracks provide reliable data for motion reconstruction, irrespective of sediment conditions.
• The study validates the use of subsurface track morphology for paleo-motion analysis.