The Sirius Passet Lagerstätte of North Greenland: a remote window on the Cambrian Explosion

Abstract

The lower Cambrian Lagerstätte of Sirius Passet, Peary Land, North Greenland, is one of the oldest of the Phanerozoic exceptionally preserved biotas. The Lagerstätte evidences the escalation of numbers of new body plans and life modes that formed the basis for a modern, functionally tiered ecosystem. The fauna is dominated by predators, infaunal, benthic and pelagic, and the presence of abundant nekton, including large sweep-net feeders, suggests an ecosystem rich in nutrients. Recent discoveries have helped reconstruct digestive systems and their contents, muscle fibres, and visual and nervous systems for a number of taxa. New collections have confirmed the complex combination of taphonomic pathways associated with the biota and its potentially substantial biodiversity. These complex animal-based communities within the Buen Formation were associated with microbial matgrounds, now preserved in black mudstones deposited below storm wave base that provide insight into the shift from late Neoproterozoic (Ediacaran) to Cambrian substrates and communities. Moreover, the encasing sediment holds important data on the palaeoenvironment and the water-column chemistry, suggesting that these animal-based communities developed in conditions with very low oxygen concentrations.

Computed tomography sheds new light on the affinities of the enigmatic euarthropod Jianshania furcatus from the early Cambrian Chengjiang biota

“…Since its discovery in 1984, the Chengjiang biota has been a focal point of intense palaeobiological scrutiny due to the abundance of non-biomineralized macrofossils resulting from organic carbon preservation and decay-induced pyritization by sulphur-reducing bacteria [14,15]. Similar to other major Cambrian Konservat-Lagerstätten around the world [16][17][18][19][20], the metazoan community preserved in Chengjiang is dominated by euarthropods in terms of species richness and abundance, which in addition to a rich trilobite fauna also includes several dozens of non-biomineralized taxa [12,21,22]. The superb quality of soft-tissue preservation in Chengjiang fossils has produced deep insights into the biology of Cambrian euarthropods, informing about important aspects of their internal anatomy such as the digestive tract [23][24][25] and nervous system [26][27][28], as well as insights into their behavior and ecology [29][30][31].…”

The oldest palaeoloricate mollusc (Cambrian Series 2, Stage 4; North Greenland) and its bearing on aculiferan evolution

“…Zhao et al (2017) argued that a radula was not present in Halkieria because one is not preserved in material from the Sirius Passet Lagerstätte, while a radula is preserved in Wiwaxia from the Burgess Shale Lagerstätte and Calvapilosa from Fezouata Lagerstätte. This argumentation is rejected and seems to demonstrate a lack of awareness of both the complexity and variable nature of preservation at Sirius Passet (Strang et al 2016a, b;Peel & Ineson 2011a;Peel 2017;Hammarlund et al 2019;Harper et al 2019) where exceptional preservation was not afforded equally to all members of the biota. Individual taxa followed their own post mortem preservational pathways, some with preserved soft parts and some without.…”

“…The latter formation crops out extensively across eastern areas of North Greenland and yields rich faunas indicative of Cambrian Stages 3 and 4 (Peel & Willman 2018). The Sirius Passet Lagerstätte of northwestern Peary Land is located within basal strata of the Buen Formation transitional to a deep water trough siliciclastic succession to the north (Conway Morris et al 1987;Ineson & Peel 2011;Peel & Ineson 2011a, b;Harper et al 2019;Fig. 2).…”

“…7A-D). Fully articulated specimens of Halkieria evangelista are a key element in the diverse fauna of the Sirius Passet Lagerstätte (Conway Morris et al 1987;Conway Morris & Peel 1995;Ineson & Peel 2011;Peel & Ineson 2011a, b;Harper et al 2019). The single locality with exceptionally preserved fossils ( Fig.…”

Early Palaeozoic diversifications and extinctions in the marine biosphere: a continuum of change

“…Hou et al 2017;Yang et al 2018) in South China, Sirius Passet in North Greenland (e.g. Harper et al 2019a) and others. Among the other key biotas that have been described more recently, the Qingjiang biota from South China (Fu et al 2019) is the most spectacular, but other discoveries are still to be made.…”