Organic-walled microfossils of the mid-Neoproterozoic Alinya Formation, Officer Basin, Australia

• Published in: Journal of paleontology Vol. 90; no. 5; pp. 854 - 887
• Main Authors: Riedman, Leigh Anne, Porter, Susannah
• Format: Journal Article
• Language: English
• Published: New York, USA The Paleontological Society 01-09-2016; Cambridge University Press; Paleontological Society; SEPM Society for Sedimentary Geology
• Subjects: Alinya Formation; Australasia; Australia; Caelatimurus foveolatus; cores; Culcitulisphaera revelata; electron microscopy data; Eukaryotes; faunal studies; Fossils; Giles 1 Core; Karenagare alinyaensis; Light microscopy; lithostratigraphy; microfossils; Morgensternia officerensis; morphology; Neoproterozoic; new names; new taxa; Officer Basin; Paleontology; Precambrian; problematic fossils; problematic microfossils; Proterozoic; Scanning electron microscopy; SEM data; South Australia; Species richness; taxonomy; upper Precambrian; Vidalopalla verrucata; Australia
• ISSN: 0022-3360; 1937-2337
• DOI: 10.1017/jpa.2016.49

Estimates of Precambrian eukaryotic diversity and disparity indicate broad trends of increase in the Mesoproterozoic Era, leading to a peak and then rapid decline by ca. 750 Ma. The organic-walled microfossil assemblage presented here is representative of that mid-Neoproterozoic height of eukaryotic species richness. Organic-rich shales and siltstones of the mid-Neoproterozoic upper Alinya Formation, eastern Officer Basin, Australia, preserve an abundant and diverse assemblage of organic-walled microfossils deposited in a low-latitude, shallow marine setting. Use of scanning electron microscopy (SEM) revealed an unexpected level of morphological detail not visible in transmitted light microscopy. This led to the recognition of new species as well as establishment of degradational sequences, which aid in fossil recognition. In total, 26 taxa are described here; these include 21 previously named forms, four newly described species (Caelatimurus foveolatus, Culcitulisphaera revelata, Karenagare alinyaensis, and Morgensternia officerensis), and one new combination (Vidalopalla verrucata).