Non-avian dinosaur eggshell calcite can contain ancient, endogenous amino acids
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Non-avian dinosaur eggshell calcite can contain ancient, endogenous amino acids. / Saitta, Evan T.; Vinther, Jakob; Crisp, Molly K.; Abbott, Geoffrey D.; Wheeler, Lucy; Presslee, Samantha; Kaye, Thomas G.; Bull, Ian; Fletcher, Ian; Chen, Xinqi; Vidal, Daniel; Sanguino, Fernando; Buscalioni, Ángela D.; Calvo, Jorge; Sereno, Paul C.; Baumgart, Stephanie L.; Pittman, Michael; Collins, Matthew J.; Sakalauskaite, Jorune; Mackie, Meaghan; Bello, Federica Dal; Dickinson, Marc R.; Stevenson, Mark A.; Donohoe, Paul; Heck, Philipp R.; Demarchi, Beatrice; Penkman, Kirsty E. H.
In: Geochimica et Cosmochimica Acta, Vol. 365, 2024, p. 1-20.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Non-avian dinosaur eggshell calcite can contain ancient, endogenous amino acids
AU - Saitta, Evan T.
AU - Vinther, Jakob
AU - Crisp, Molly K.
AU - Abbott, Geoffrey D.
AU - Wheeler, Lucy
AU - Presslee, Samantha
AU - Kaye, Thomas G.
AU - Bull, Ian
AU - Fletcher, Ian
AU - Chen, Xinqi
AU - Vidal, Daniel
AU - Sanguino, Fernando
AU - Buscalioni, Ángela D.
AU - Calvo, Jorge
AU - Sereno, Paul C.
AU - Baumgart, Stephanie L.
AU - Pittman, Michael
AU - Collins, Matthew J.
AU - Sakalauskaite, Jorune
AU - Mackie, Meaghan
AU - Bello, Federica Dal
AU - Dickinson, Marc R.
AU - Stevenson, Mark A.
AU - Donohoe, Paul
AU - Heck, Philipp R.
AU - Demarchi, Beatrice
AU - Penkman, Kirsty E. H.
N1 - Publisher Copyright: © 2023 Elsevier Ltd
PY - 2024
Y1 - 2024
N2 - Proteins are the most stable of the macromolecules that carry genetic information over long periods of time. Closed systems are more likely to retain endogenous proteins or their degradation products. Amino acid racemisation data in experimental and subfossil material suggests that mollusc shell and avian eggshell calcite crystals can demonstrate closed system behaviour, retaining endogenous amino acids. Here, Late Cretaceous (Campanian–Maastrichtian) Argentine titanosaurian sauropod eggshells show dark, organic stains under light microscopy/photography and fluorescence imaging. Raman spectroscopy can yield bands consistent with various organic molecules, possibly including N-bearing molecules or geopolymers. Pyrolysis-gas chromatography-mass spectrometry reveals pyrolysates consistent with amino acids as well as aliphatic hydrocarbon homologues that are not present in modern eggshell, consistent with kerogen formation deriving from eggshell lipids. High-performance liquid chromatography reveals that their intra-crystalline fraction can be enriched in some of the most stable amino acids (Glx, Gly, Ala, and possibly Val) and are fully racemic (despite being some of the slowest racemising amino acids), indicating ancient origin. This preservation varies across localities, but similar ancient amino acid profiles were also observed in Late Cretaceous Spanish titanosaurians from several localities and Chinese putative hadrosaurid eggshell. These amino acid results are consistent with previous studies on degradation trends deduced from modern, thermally matured, sub-fossil, and ∼3.8–6.5 Ma avian eggshell, as well as ∼30 Ma calcitic mollusc opercula. Selective preservation of certain fully racemic amino acids, which do not racemise in-chain, and the concentration of free amino acids suggests likely complete hydrolysis of original peptides. Liquid chromatography-tandem mass spectrometry supports this hypothesis by failing to detect any non-contamination peptide sequences from the Mesozoic eggshell. These closed-system amino acids are possibly the most thoroughly supported non-avian dinosaur endogenous protein-derived constituents, at least those that have not undergone oxidative condensation with other classes of biomolecules. Biocrystal matrices can help preserve mobile organic molecules by trapping them (perhaps with the assistance of resistant organic polymers), but trapped organics are nevertheless prone to diagenetic degradation, even if such reactions might be slowed in exceptional circumstances. Future work should survey fossil biocalcite to determine variability in amino acid preservation.
AB - Proteins are the most stable of the macromolecules that carry genetic information over long periods of time. Closed systems are more likely to retain endogenous proteins or their degradation products. Amino acid racemisation data in experimental and subfossil material suggests that mollusc shell and avian eggshell calcite crystals can demonstrate closed system behaviour, retaining endogenous amino acids. Here, Late Cretaceous (Campanian–Maastrichtian) Argentine titanosaurian sauropod eggshells show dark, organic stains under light microscopy/photography and fluorescence imaging. Raman spectroscopy can yield bands consistent with various organic molecules, possibly including N-bearing molecules or geopolymers. Pyrolysis-gas chromatography-mass spectrometry reveals pyrolysates consistent with amino acids as well as aliphatic hydrocarbon homologues that are not present in modern eggshell, consistent with kerogen formation deriving from eggshell lipids. High-performance liquid chromatography reveals that their intra-crystalline fraction can be enriched in some of the most stable amino acids (Glx, Gly, Ala, and possibly Val) and are fully racemic (despite being some of the slowest racemising amino acids), indicating ancient origin. This preservation varies across localities, but similar ancient amino acid profiles were also observed in Late Cretaceous Spanish titanosaurians from several localities and Chinese putative hadrosaurid eggshell. These amino acid results are consistent with previous studies on degradation trends deduced from modern, thermally matured, sub-fossil, and ∼3.8–6.5 Ma avian eggshell, as well as ∼30 Ma calcitic mollusc opercula. Selective preservation of certain fully racemic amino acids, which do not racemise in-chain, and the concentration of free amino acids suggests likely complete hydrolysis of original peptides. Liquid chromatography-tandem mass spectrometry supports this hypothesis by failing to detect any non-contamination peptide sequences from the Mesozoic eggshell. These closed-system amino acids are possibly the most thoroughly supported non-avian dinosaur endogenous protein-derived constituents, at least those that have not undergone oxidative condensation with other classes of biomolecules. Biocrystal matrices can help preserve mobile organic molecules by trapping them (perhaps with the assistance of resistant organic polymers), but trapped organics are nevertheless prone to diagenetic degradation, even if such reactions might be slowed in exceptional circumstances. Future work should survey fossil biocalcite to determine variability in amino acid preservation.
KW - Amino Acids
KW - Eggshell
KW - Fossils
KW - Proteins
KW - Taphonomy
U2 - 10.1016/j.gca.2023.11.016
DO - 10.1016/j.gca.2023.11.016
M3 - Journal article
AN - SCOPUS:85179097712
VL - 365
SP - 1
EP - 20
JO - Geochimica et Cosmochimica Acta. Supplement
JF - Geochimica et Cosmochimica Acta. Supplement
SN - 0046-564X
ER -
ID: 378949634