Skin, scales, and cells in a Jurassic plesiosaur

Area of Science:

• Paleontology
• Marine Biology
• Evolutionary Biology

Background:

• Plesiosaurs were dominant marine reptiles during the Mesozoic Era.
• Fossilized soft tissues of plesiosaurs are extremely rare, limiting our understanding of their integument.
• Skeletal remains are found globally, but detailed information on skin structure is scarce.

Purpose of the Study:

• To investigate the integument of a well-preserved plesiosaur fossil.
• To analyze the composition and structure of fossilized skin from plesiosaurs.
• To infer the paleoecology and functional morphology of plesiosaur skin.

Main Methods:

• Analysis of a Lower Jurassic plesiosaur fossil from the Posidonia Shale of Germany.
• Microscopic examination of skin traces from the tail and front flipper.
• Molecular analysis to identify organic residues in the integument.
• Comparison of fossilized structures with modern reptilian integument.

Main Results:

• The plesiosaur tail integument was scale-less and preserved epidermal layers, melanosomes, and keratinocytes with cell nuclei.
• Molecular analysis indicated the presence of degraded original organic compounds.
• The front flipper integument featured small, sub-triangular structures resembling modern reptilian scales.
• These scale-like structures may have aided in hydrodynamics or benthic substrate interaction.

Conclusions:

• Plesiosaur integument varied, with scale-less tails and potentially scaled flippers.
• The presence of scales on flippers could have enhanced hydrodynamic performance or substrate traction.
• Integumentary features likely played a significant role in plesiosaur paleoecology, similar to other marine reptiles.