Mauritian snail shells show evidence of extinct predators

Area of Science:

• Paleontology
• Malacology
• Evolutionary Biology

Background:

• Fossil shells of several Tropidophora land snail species from Mauritius, dating from ~1426 BCE to ~1090 CE, predate human discovery and settlement.
• These ancient shells exhibit characteristic predatory holes, indicating interactions with predators before significant human impact.

Purpose of the Study:

• To investigate the nature and cause of predatory holes found on fossil Tropidophora snail shells from Mauritius.
• To identify the extinct predators responsible for these shell damages.

Main Methods:

• Comparative analysis of predatory hole morphology on fossil snail shells.
• Comparison of shell damage with known boring mechanisms of potential invertebrate and vertebrate predators.
• Examination of shell microstructures and associated features like depressions and grooves.

Main Results:

• Two types of predatory holes were identified: large, irregular holes on T. carinata, and smaller, regular circular holes on T. ligata, T. icterica, and T. michaudi.
• Irregular holes are likely caused by the extinct red rail (Aphanapteryx bonasia).
• Circular holes, previously unreported, closely resemble damage caused by extinct rathouisiid slugs, suggesting a new extinct predator-prey interaction.

Conclusions:

• The study identifies two distinct extinct predators of Tropidophora snails on Mauritius: the red rail and an unknown rathouisiid slug.
• These findings highlight an extinct predatory interaction, offering insights into the paleoecology of Mauritius before human colonization.