Heda Agić is a palaeontologist based at Uppsala University, Sweden, where she recently defended her PhD thesis on the diversification of early photosynthetic eukaryotes. Previously, she gained an undergraduate degree in Earth sciences at University College London and completed a master’s thesis dealing with small shelly fossils at the same institution. Her work focuses on studying the morphology and microstructure of organic-walled microfossil assemblages from China, Estonia, Sweden and Norway to answer questions about early eukaryotic evolution. Her other interests include taphonomy of organically preserved fossils, as well as drastic environmental and biological changes during the Neoproterozoic era. When not staring down a microscope or in the field, Heda is making sci-fi props and fossil jewellery.
Dr. Heda Agić, Department of Earth Sciences, Uppsala University, Sweden. Email: email@example.com
by Heda Agić*1
The acritarchs are a major, long-ranging and successful group of small, capsule-like, organically preserved fossils, which are present in the rock record of most of Earth’s history, dating back 1.8 billion year, or perhaps even as many as 3.4 billion years (Fig. 1). They include mostly single-celled microfossils ranging from a few micrometres (one-millionth of a metre) to one millimetre in size, and each is made up of a sac of organic tissue (vesicle). They are most commonly round, and can be either smooth or covered in spines (Fig. 2). Acritarchs are found in rock deposits that were once marine and terrestrial aquatic environments, and have been described from localities on all continents, as well as from all time periods from the Proterozoic eon (starting 2