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| Preservado por milhões de anos? |
Feathers are amongst the most
complex epidermal structures known, and they have a well-documented
evolutionary trajectory across non-avian dinosaurs and basal birds. Moreover,
melanosome-like microbodies preserved in association with fossil plumage have
been used to reconstruct original colour, behaviour and physiology. However,
these putative ancient melanosomes might alternatively represent
microorganismal residues, a conflicting interpretation compounded by a lack of
unambiguous chemical data. We therefore used sensitive molecular imaging,
supported by multiple independent analytical tests, to demonstrate that the
filamentous epidermal appendages in a new specimen of the Jurassic paravian
Anchiornis comprise remnant eumelanosomes and fibril-like microstructures,
preserved as endogenous eumelanin and authigenic calcium phosphate. These results provide novel insights into the early
evolution of feathers at the sub-cellular level, and unequivocally determine
that melanosomes can be preserved in fossil feathers. [Sem tempo para traduzir…]
(Scientific Reports; PDF grátis)
Nota do blog Desafiando a Nomenklatura Científica: “Uma pergunta causticante:
Pode
isso, Arnaldo? A regra é clara: pigmentos não podem durar todos esses milhões
de anos. Ora, se o pigmento em penas fossilizadas não pode durar 150 milhões de
anos, quer dizer então que a estória da evolução dos dinossauros a partir de
aves está errada? Pano rápido!”
