New trace fossil evidence for an early recovery signal in the aftermath of the end-Permian mass extinction
Abstract New ichnological data from the Lower Triassic Werfen Formation (Dolomites, Italy) revealed an unexpectedly diverse and complex ichnofauna in mixed siliclastic–carbonate shelf sediments of the western tropical Tethys shortly after the end-Permian mass extinction event. Common elements are Thalassinoides , Palaeophycus and Planolites . Other associated ichnogenera include Spongeliomorpha , Rhizocorallium , Lockeia , Catenichnus , Helminthopsis , and Taenidium . One structure is tentatively determined as Curvolithus . Biostratigraphic data (conodonts and bivalves) of the trace fossil interval (lower Seis/Siusi Member) suggest a late Griesbachian age, less than 1 Ma after the end-Permian mass extinction event. Similarly diverse ichnofossil communities from this time interval have recently been described from the Boreal Realm, but this is the first record of a diverse Griesbachian ichnoassemblage from the tropics, indicating that the early recovery of trace fossil producers was not latitudinally restricted, as previously proposed. Accordingly, relatively advanced recovery stages were reached on a global scale much earlier than the Spathian as is commonly acknowledged. The early and interregional peak in ichnofaunal recovery implies subsequent ecological setbacks in post-Griesbachian times that explain the overall delay of benthic recovery until the Spathian. Rather than persistent catastrophic conditions during the Griesbachian, a global and synchronous succession of crises and relaxation phases after the Griesbachian is proposed as an explanatory model for the recovery pattern of benthic ecosystems.