In News:

For the first time, scientists have successfully extracted and analyzed 18–24 million-year-old enamel proteins from extinct mammal fossils—pushing the frontiers of biomolecular preservation and reshaping our understanding of mammalian evolution. The groundbreaking findings were published in Nature (July 2025) and draw from fossils found in Lake Turkana Basin (Kenya) and the Haughton Impact Crater (Canada's High Arctic).

Key Highlights:

What was Discovered?

• Enamel proteins, trapped in the dense tooth enamel of extinct mammals, were recovered from fossils dating back 18–24 million years.
• These proteins are now the oldest biomolecular sequences ever recovered, exceeding the time limits of ancient DNA (which typically degrades within 1 million years).

Significance of Enamel Proteins:

• Enamel—being the hardest biological substance—acts as a molecular vault, shielding proteins from environmental degradation.
• These ancient proteins provide crucial phylogenetic information, even in hot tropical zones like Lake Turkana, where preservation was previously thought improbable.

Methodology:

• Researchers extracted structural enamel proteins like amelogenin, enamelin, and ameloblastin.
• Advanced mass spectrometry and rigorous contamination controls ensured data integrity.
• Over 1,000 peptides and 7 different enamel proteins were recovered from a 21–24 million-year-old rhinoceros tooth in the Arctic.
• Diagenetic alterations (e.g., oxidation, glycation) were used as authenticity markers.

Site-Wise Discoveries:

Lake Turkana Basin (Kenya):

• Fossils from a hot, arid region yielded enamel proteins up to 18 million years old.
• Demonstrated exceptional preservation due to fluviodeltaic sedimentation, which allowed rapid burial and protection from oxygen and heat.
• The Turkana Basin is a major palaeontological site in Eastern Rift Valley and home to species like proboscideans, rhinocerotids, hippopotamids, and hominoids.
• Enamel samples ranged from 1.5 to 29 million years old.
• Turkana Lake, the world’s largest permanent desert lake and a UNESCO World Heritage Site, lies in this region.

Haughton Impact Crater (Nunavut, Canada):

• Ancient enamel from a permafrost site enabled recovery of 21–24 million-year-old proteins.
• The site was once a temperate lake, aiding preservation under low oxygen (anoxic) conditions.
• Researchers reconstructed rhinocerotid evolution, showing Epiaceratherium diverged before the Elasmotheriinae-Rhinocerotinae split, revising long-held fossil-based phylogenies.

Scientific Implications: