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Fossil collagen survival thanks to triple helix structure + Eosuchus (gavialoid) endocranial anatomy and oceanic dispersal (free pdfs)

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Ben Creisler

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Sep 4, 2024, 2:21:00 PM9/4/24
to DinosaurMa...@googlegroups.com

Ben Creisler


Some recent papers:

Free pdf:

Jinyi Yang, Volga Kojasoy, Gerard J. Porter & Ronald T. Raines (2024)
Pauli Exclusion by n→π* Interactions: Implications for Paleobiology
ACS Central Science (advance online publication)
doi: https://doi.org/10.1021/acscentsci.4c00971
https://pubs.acs.org/doi/10.1021/acscentsci.4c00971




Proteins have evolved to function in an aqueous environment. Collagen, which provides the bodily scaffold for animals, has a special need to retain its integrity. This need was addressed early on, as intact collagen has been detected in dinosaur fossils, even though peptide bonds have a half-life of only ∼500 years in a neutral aqueous solution. We sought to discover the physicochemical basis for this remarkable resistance to hydrolysis. Using experimental and computational methods, we found that a main-chain acyl group can be protected from hydrolysis by an O···C═O n→π* interaction with a neighboring acyl group. These interactions engage virtually every peptide bond in a collagen triple helix. This protection, which arises from the Pauli exclusion principle, could underlie the preservation of ancient collagen.

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News:

How can collagen survive in dinosaur fossils for millions of years?
The bonds of most proteins break after around 500 years, but collagen has been found preserved for nearly 200m years. MIT researchers think the reason lies in its triple helix structure.

https://www.siliconrepublic.com/innovation/how-did-collagen-survive-in-dinosaur-fossils

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Free pdf:

Paul M. J. Burke, Sophie A. Boerman, Gwendal Perrichon, Jeremy E. Martin, Thierry Smith, Johan Vellekoop & Philip D. Mannion (2024)
Endocranial anatomy and phylogenetic position of the crocodylian Eosuchus lerichei from the late Paleocene of northwestern Europe and potential adaptations for transoceanic dispersal in gavialoids
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.25569
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25569

Free pdf:
https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.25569


Eosuchus lerichei is a gavialoid crocodylian from late Paleocene marine deposits of northwestern Europe, known from a skull and lower jaws, as well as postcrania. Its sister taxon relationship with the approximately contemporaneous species Eosuchus minor from the east coast of the USA has been explained through transoceanic dispersal, indicating a capability for salt excretion that is absent in extant gavialoids. However, there is currently no anatomical evidence to support marine adaptation in extinct gavialoids. Furthermore, the placement of Eosuchus within Gavialoidea is labile, with some analyses supporting affinities with the Late Cretaceous to early Paleogene “thoracosaurs.” Here we present novel data on the internal and external anatomy of the skull of E. lerichei that enables a revised diagnosis, with 6 autapomorphies identified for the genus and 10 features that enable differentiation of the species from Eosuchus minor. Our phylogenetic analyses recover Eosuchus as an early diverging gavialid gavialoid that is not part of the “thoracosaur” group. In addition to thickened semi-circular canal walls of the endosseous labyrinth and paratympanic sinus reduction, we identify potential osteological correlates for salt glands in the internal surface of the prefrontal and lacrimal bones of E. lerichei. These salt glands potentially provide anatomical evidence for the capability of transoceanic dispersal within Eosuchus, and we also identify them in the Late Cretaceous “thoracosaur” Portugalosuchus. Given that the earliest diverging and stratigraphically oldest gavialoids either have evidence for a nasal salt gland and/or have been recovered from marine deposits, this suggests the capacity for salt excretion might be ancestral for Gavialoidea. Mapping osteological and geological evidence for marine adaptation onto a phylogeny indicates that there was probably more than one independent loss/reduction in the capacity for salt excretion in gavialoids.

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