An ancestral hard-shelled sea turtle with a mosaic of soft skin and scutes

Summary, in English

The transition from terrestrial to marine environments by secondarily aquatic tetrapods necessitates a suite of adaptive changes associated with life in the sea, e.g., the scaleless skin in adult individuals of the extant leatherback turtle. A partial, yet exceptionally preserved hard-shelled (Pan-Cheloniidae) sea turtle with extensive soft-tissue remains, including epidermal scutes and a virtually complete flipper outline, was recently recovered from the Eocene Fur Formation of Denmark. Examination of the fossilized limb tissue revealed an originally soft, wrinkly skin devoid of scales, together with organic residues that contain remnant eumelanin pigment and inferred epidermal transformation products. Notably, this stem cheloniid—unlike its scaly living descendants—combined scaleless limbs with a bony carapace covered in scutes. Our findings show that the adaptive transition to neritic waters by the ancestral pan-chelonioids was more complex than hitherto appreciated, and included at least one evolutionary lineage with a mosaic of integumental features not seen in any living turtle.

• Author: Randolph Glenn De La Garza; Henrik Madsen; Peter Sjövall; Frank Osbӕck; Wenxia Zheng; Martin Jarenmark; Mary H. Schweitzer; Anders Engdahl; Per Uvdal; Mats E. Eriksson; Johan Lindgren
• Department/s: Lithosphere and Biosphere Science; Medical Microspectroscopy; NanoLund: Centre for Nanoscience; MultiPark: Multidisciplinary research focused on Parkinson´s disease; LTH Profile Area: Photon Science and Technology; Chemical Physics
• Publishing year: 2022-12
• Language: English
• Publication/Series: Scientific Reports
• Volume: 12
• Issue: 1
• Links: http://dx.doi.org/10.1038/s41598-022-26941-1
• Document type: Journal article
• Publisher: Nature Publishing Group
• Topic: Evolutionary Biology
• Status: Published
• Research group: Medical Microspectroscopy
• ISBN/ISSN/Other: ISSN: 2045-2322