Exceptional soft tissues preservation in a mummified frog-eating Eocene salamander

Area of Science:

• Paleontology
• Vertebrate Anatomy
• Taphonomy

Background:

• Fossils typically preserve hard tissues like bones.
• Three-dimensional preservation of soft tissues in vertebrates is exceptionally rare.
• Understanding ancient ecosystems requires knowledge of soft tissue anatomy.

Purpose of the Study:

• To document and analyze an exceptionally preserved three-dimensionally mummified salamander fossil.
• To investigate the soft tissue anatomy of an extinct salamander, Phosphotriton sigei.
• To reconstruct the ecology and lifestyle of P. sigei based on fossil evidence.

Main Methods:

• Phase-contrast synchrotron X-ray microtomography for non-destructive imaging.
• Analysis of skeletal and external morphology.
• Identification and study of preserved soft tissues including organs and gut contents.

Main Results:

• Exceptional 3D preservation of soft tissues (lung, spinal cord, nerves, digestive tract, muscles, urogenital organs) in a salamander fossil (40-34 million years old).
• Discovery of frog remains in the digestive tract, indicating rare predatory behavior for an extinct salamander.
• Bone microanatomy suggests an amphibious or terrestrial lifestyle, not neotenic.

Conclusions:

• This fossil represents one of the oldest known 3D soft tissue preservation in vertebrates.
• The findings enhance understanding of early urodele (salamander) anatomy and evolutionary biology.
• The unique diet provides insights into paleoecology and predator-prey dynamics.