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Johan Lindgren

Johan Lindgren

Senior lecturer

Johan Lindgren

Biochemistry and adaptive colouration of an exceptionally preserved juvenile fossil sea turtle


  • Johan Lindgren
  • Takeo Kuriyama
  • Henrik Madsen
  • Peter Sjövall
  • Wenxia Zheng
  • Per Uvdal
  • Anders Engdahl
  • Alison Moyer
  • Johan Gren
  • Naoki Kamezaki
  • Shintaro Ueno
  • Mary Higby Schweitzer

Summary, in English

The holotype (MHM-K2) of the Eocene cheloniine Tasbacka danica is arguably one of the best preserved juvenile fossil sea turtles on record. Notwithstanding compactional flattening, the specimen is virtually intact, comprising a fully articulated skeleton exposed in dorsal view. MHM-K2 also preserves, with great fidelity, soft tissue traces visible as a sharply delineated carbon film around the bones and marginal scutes along the edge of the carapace. Here we show that the extraordinary preservation of the type of T. danica goes beyond gross morphology to include ultrastructural details and labile molecular components of the once-living animal. Haemoglobin-derived compounds, eumelanic pigments and proteinaceous materials retaining the immunological characteristics of sauropsid-specific β-keratin and tropomyosin were detected in tissues containing remnant melanosomes and decayed keratin plates. The preserved organics represent condensed remains of the cornified epidermis and, likely also, deeper anatomical features, and provide direct chemical evidence that adaptive melanism – a biological means used by extant sea turtle hatchlings to elevate metabolic and growth rates – had evolved 54 million years ago.


  • Lithosphere and Biosphere Science
  • Chemical Physics
  • MAX IV Laboratory

Publishing year





Scientific Reports





Document type

Journal article


Nature Publishing Group


  • Geology
  • Geochemistry




  • ISSN: 2045-2322