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La scienza non è ancora in grado di dare una spiegazione univoca su cosa provocò, 66 milioni di anni fa, l'estinzione dei dinosauri. Allo stesso periodo, ciò è ormai appurato, risalgono sia l'impatto sul pianeta di un'enorme meteora, sia un'estrema attività vulcanica. Ma quale fenomeno si manifestò per primo?
L'ipotesi del vulcanismo, e dei micidiali sconvolgimenti del clima che determinò, torna ad imporsi. Almeno stando agli ultraprecisi metodi di datazione utilizzati dall'équipe di Thierry Adatte, geologo dell'Università di Losanna.
Questi hanno evidenziato un'attività vulcanica intensa che precedette di 30'000-50'000 anni il limite dell'estinzione. "Ciò implica", spiega lo scienziato, "che c'erano già condizioni estremamente logoranti per il pianeta, prima della caduta della meteora".
Quest'ultima, con le sue devastazioni, avrebbe in qualche modo "finito il lavoro": in buona sostanza completò, "come la goccia che fa traboccare il vaso", il processo di estinzione di massa già innescato dal vulcanismo.
RTS/ARi
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