| Summary: | Ediacarans make up the oldest known truly diverse metazoan assemblages and are known globally. However, few sites have produced abundant fossils, and until recently such fossils were unknown in Arabia. Generally restricted to the late Neoproterozoic, the best known assemblages occur in China, Newfoundland, the White Sea in northern Russia, the Flinders Ranges of South Australia and southern Namibia in Africa. Less diverse assemblages are known from Siberia, Ukraine, UK, and a few sites in Asia, and North and South America. Ediacarans occur primarily in shallow marine derived sands and clays with the exception of Newfoundland forms that may have inhabited light free depths in a volcanically active terrane. They are known in rock sequences dating from 630 Ma to 540 Ma, the Ediacaran or Vendian period, the youngest division of Precambrian time. New discoveries in Saudi Arabia over the past 5 years have brought to light the presence of Ediacarans, both traces and body fossils, suggesting that further investigation most likely will yield a much more diverse assemblage, and one that may well have inhabited less saline environs that is typical for other Ediacarans. Fossils similar to Harlaniella, known elsewhere from the late Precambrian and Cambrian, and megascopic frond-like forms have been discovered in a single layer that is overtopped by a volcanic ash, dated at 569 ± 3 Ma, thus giving both good preservation and precision dating of the Dhaiqa formation in the Dhaiqa basin and its enclosed Ediacarans. In addition, the discovery of Horodyskia-like fossils in the Jif ’n basin is a first occurrence for Saudi Arabia. They have a similar Neoproterozoic age to forms found in China, both of which are signifi cantly younger than the more than 1 billion year old forms found in North America and Australia.
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