Animal survival strategies in Neoproterozoic ice worlds. Issue 1 (11th October 2022)

• Record Type: Journal Article
• Authors: Griffiths, Huw J.; Whittle, Rowan J.; Mitchell, Emily G.
• Is Part Of: Global change biology. Volume 29:Issue 1(2023)
• Page Start: 10
• Page End: 20
• Publication Date: 2022-10-11
• Subjects: Cryogenian -- Ediacaran -- Gaskiers -- Marinoan -- polar -- slushball Earth -- snowball Earth -- Sturtian; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.16393
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: The timing of the first appearance of animals is of crucial importance for understanding the evolution of life on Earth. Although the fossil record places the earliest metazoans at 572–602 Ma, molecular clock studies suggest a far earlier origination, as far back as ~850 Ma. The difference in these dates would place the rise of animal life into a time period punctuated by multiple colossal, potentially global, glacial events. Although the two schools of thought debate the limitations of each other's methods, little time has been dedicated to how animal life might have survived if it did arise before or during these global glacial periods. The history of recent polar biota shows that organisms have found ways of persisting on and around the ice of the Antarctic continent throughout the Last Glacial Maximum (33–14 Ka), with some endemic species present before the breakup of Gondwana (180–23 Ma). Here we discuss the survival strategies and habitats of modern polar marine organisms in environments analogous to those that could have existed during Neoproterozoic glaciations. We discuss how, despite the apparent harshness of many ice covered, sub‐zero, Antarctic marine habitats, animal life thrives on, in and under the ice. Ice dominated systems and processes make some local environments more habitable through water circulation, oxygenation, terrigenous nutrient input and novel habitats. We consider how the physical conditions of Neoproterozoic glaciations would likely have dramatically impacted conditions for potential life in the shallows and erased any possible fossil evidence from the continental shelves. The recent glacial cycle has driven the evolution of Antarctica's unique fauna by acting as a "diversity pump, " and the same could be true for the late Proterozoic and the evolution of animal life on Earth, and the existence of life elsewhere in the universe on icy worlds or moons. Abstract : The fossil record places the earliest metazoans at 572–602 Ma, whilst molecular clock studies suggest an earlier origination, up to ~850 Ma, during a time punctuated by multiple global glacial events (snowball and slushball Earths). If animal life did arise before or during these glacial periods it would have faced conditions analogous with modern polar marine habitats, requiring similar survival strategies. Ice dominated systems make some environments more habitable and recent glacial cycles have driven the evolution of Antarctica's unique fauna, the same could be true for the late Proterozoic and the evolution of animal life on Earth.