* Astronomy

Melanin pigment preserved in 160 million-year-old Jurassic fossils

Researchers have detected intact melanin in 160 million-year-old fossilised cephalopod ink sacs in the United Kingdom, according to a study. To ascertain the presence of the colouring pigment melanin in the fossil record, researchers have long relied on indirect methods, suggesting poor preservation of the pigment over geologic time. For example, researchers have reconstructed the plumage patterns of dinosaurs through visual evidence of organelle-like structures bearing melanin pigments. John D. Simon and colleagues used a combination of direct, high-resolution chemical techniques and identified a wide range of signatures unique to a form of brownish-black melanin called eumelanin, known to play biologically-important roles in display and camouflage, in 160 million-year-old fossils of cephalopod ink sacs preserved in Jurassic-age deposits in Wiltshire and Dorset in the United Kingdom. The authors report that the chemical signatures strongly suggest the similarity of the eumelanin pigment in the fossilised ink sacs to the melanin of the modern cuttlefish Sepia officinalis, found in the Mediterranean, North, and Baltic Seas. The authors' chemical analysis revealed that the fossil pigment was unlikely to be of the less-common, orange-hued variety of melanin called pheomelanin. Given that melanin appears to have survived fossilisation, the authors reason, other biologically relevant organic compounds might lie undiscovered in the fossil record.

Title: Direct chemical evidence for eumelanin pigment from the Jurassic period
Authors: Keely Glass, Shosuke Ito, Philip R. Wilby, Takayuki Sota, Atsushi Nakamura, C. Russell Bowers, Jakob Vinther, Suryendu Dutta, Roger Summons, Derek E. G. Briggs, Kazumasa Wakamatsu, and John D. Simon

Melanin is a ubiquitous biological pigment found in bacteria, fungi, plants, and animals. It has a diverse range of ecological and biochemical functions, including display, evasion, photoprotection, detoxification, and metal scavenging. To date, evidence of melanin in fossil organisms has relied entirely on indirect morphological and chemical analyses. Here, we apply direct chemical techniques to categorically demonstrate the preservation of eumelanin in two > 160 Ma Jurassic cephalopod ink sacs and to confirm its chemical similarity to the ink of the modern cephalopod, Sepia officinalis. Identification and characterisation of degradation-resistant melanin may provide insights into its diverse roles in ancient organisms.

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 Mobile Ammonites Stayed Put at Plains Methane Seeps

Research led by Museum scientists shows that ammonites, an extinct type of shelled mollusk that's closely related to modern-day nautiluses and squids, made homes in the unique environments surrounding methane seeps in the seaway that once covered America's Great Plains. The findings, recently published in the journal Geology, provide new insights into the mode of life and habitat of these ancient animals.
In the Black Hills region of South Dakota, researchers are investigating a 74-million-year-old mound of fossilized material where methane-rich fluids once migrated through the sediments onto the sea floor. When the face of this cliff recently slumped off, a wide variety of bivalves, sponges, corals, fish, crinoids, and, as recently documented, ammonites, were revealed.
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Ammonites

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