Deciphering deterministic factors of predation pressures in deep time.

Area of Science:

• Paleontology
• Evolutionary Biology
• Marine Biology

Background:

• Predation pressure is a key evolutionary driver, resulting from predator-prey interactions.
• Quantifying predation frequency and prey vulnerability has been challenging, limiting evolutionary insights.

Purpose of the Study:

• To quantitatively assess predation frequency, prey vulnerability, and resulting predation pressure in Eocene and Miocene marine gastropods.
• To investigate the evolutionary adaptations of prey species to predation pressure.

Main Methods:

• Utilized a modified Poisson function to quantify predation parameters.
• Analyzed fossilized marine gastropod shells from the Eocene and Miocene epochs.
• Examined shell morphology, focusing on low-spired and planispiral species, and identified internal septal structures.

Main Results:

• Low-spired shells generally exhibited higher vulnerability to predation.
• Two planispiral species showed unexpectedly low vulnerability due to defensive septal structures.
• These septal structures, analogous to those in nautiloids and ammonoids, enhanced mean lifetime by approximately 20%.

Conclusions:

• The study provides a quantitative method to trace spatio-temporal changes in predation dynamics.
• Internal shell structures can evolve as a defense mechanism against predators.
• Predation pressure and prey vulnerability are significant, quantifiable forces driving evolution over geological timescales.