The burrowing origin of modern snakes

Area of Science:

• Paleontology
• Comparative Anatomy
• Evolutionary Biology

Background:

• The origin of modern snakes is debated, with uncertainty regarding their ancestral habitat (terrestrial burrowing vs. marine swimming).
• Modern snakes utilize their inner ear to detect substrate vibrations, a key sensory adaptation.

Purpose of the Study:

• To predict the habitat of Dinilysia patagonica, an early snake species, using inner ear morphology.
• To investigate the evolutionary history of snake habitat specialization.

Main Methods:

• Analysis of x-ray virtual models of the inner ear of Dinilysia patagonica.
• Comparative analysis of vestibular shape in modern squamates (burrowers, swimmers, generalists).
• Development of predictive models for snake habitat based on vestibular morphology.

Main Results:

• Dinilysia patagonica exhibits a spherical vestibule, similar to modern burrowing squamates.
• Predictive models strongly indicate that D. patagonica and the ancestor of crown snakes were burrowers.
• A significant comparative dataset was generated for quantitative analysis of fossoriality in stem snakes.

Conclusions:

• Burrowing is inferred as the predominant ancestral habitat for the lineages leading to modern snakes.
• Inner ear morphology serves as a reliable indicator of fossoriality in extinct snake species.
• This study resolves ambiguity regarding the ancestral lifestyle of early snakes.