Reniformichnus australis n. isp.
Stephen McLoughlin, Chris Mays, Vivi Vajda, Malcolm Bocking, Tracy D. Frank & Christopher R. Fielding (2020)
Dwelling in the dead zone--vertebrate burrows immediately succeeding the end-Permian extinction event in Australia.
PALAIOS 35(8): 342â357
https://doi.org/10.2110/palo.2020.007https://pubs.geoscienceworld.org/sepm/palaios/article-abstract/35/8/342/591007/DWELLING-IN-THE-DEAD-ZONE-VERTEBRATE-BURROWSA distinctive burrow form, Reniformichnus australis n. isp., is described from strata immediately overlying and transecting the end-Permian extinction (EPE) horizon in the Sydney Basin, eastern Australia. Although a unique excavator cannot be identified, these burrows were probably produced by small cynodonts based on comparisons with burrows elsewhere that contain body fossils of the tracemakers. The primary host strata are devoid of plant remains apart from wood and charcoal fragments, sparse fungal spores, and rare invertebrate traces indicative of a very simplified terrestrial ecosystem characterizing a 'dead zone' in the aftermath of the EPE. The high-paleolatitude (~ 65-75ÂS) setting of the Sydney Basin, together with its higher paleoprecipitation levels and less favorable preservational potential, is reflected by a lower diversity of vertebrate fossil burrows and body fossils compared with coeval continental interior deposits of the mid-paleolatitude Karoo Basin, South Africa. Nevertheless, these burrows reveal the survivorship of small tetrapods in considerable numbers in the Sydney Basin immediately following the EPE. A fossorial lifestyle appears to have provided a selective advantage for tetrapods enduring the harsh environmental conditions that arose during the EPE. Moreover, high-paleolatitude and maritime settings may have provided important refugia for terrestrial vertebrates at a time of lethal temperatures at low-latitudes and aridification of continental interiors.
Highlights
First record and comprehensive analysis of Permian invertebrate and vertebrate ichnofauna from the Jebilet massif, Morocco.
First record of Sphaerapus ichnotaxa outside the United States.
First record of the Tambachichnium ichnotaxa in Africa.
Evidence for late Early Permian (Artinskian) to middle Permian (Capitanian) age of the fossil-bearing succession of Koudiat El Hamra â Haiane basin.
Data suggest that Koudiat El Hamra-Haiane and Tiddas basins are synchronous.
Abstract
The south-central Moroccan Jebilet Massif comprises several occurrences of late Paleozoic continental red-beds. These deposits have been interpreted to be of Pennsylvanian-Permian age based on lithofacies. Any other reliable age constraint for these rocks was hitherto lacking. Recent fieldwork in late Paleozoic red-beds of the Koudiat El Hamra - Haiane Basin, near the center of the Jebilet Massif, yielded a remarkable association of continental trace fossils. The assemblage includes invertebrate traces (Helminthoidichnites tenuis, Scoyenia gracilis, Sphaerapus larvalis and cf. Spongeliomorpha isp.) as well as tetrapod footprints (cf. Batrachichnus isp, Dromopus lacertoides, Hyloidichnus bifurcatus and cf. Tambachichnium isp.). The tetrapod footprints suggest a late early Permian (Artinskian) to middle Permian (Capitanian) age of the fossil-bearing strata. The Koudiat El Hamra - Haiane fossil ichnofauna is similar to the one from the north-central Moroccan Tiddas Basin, leading to the possibility that both basins developed contemporaneously.