The fossil of an animal discovered 25 years ago in a mountain area in South Africa has been identified as a new species of marine arthropod, related to today’s crabs, lobsters and spiders.
The 444-million-year-old fossil has been nicknamed 'Sue’ after the mother of its discoverer, Professor Sarah Gabbott from the University of Leicester.
Unlike most fossils, which preserve the tough outer shells of ancient creatures, Sue is special for what’s on the inside.
“Sue is an inside-out, legless, headless wonder," says Professor Gabbott. "Remarkably her insides are a mineralised time-capsule: muscles, sinews, tendons and even guts all preserved in unimaginable detail. And yet her durable carapace, legs and head are missing – lost to decay over 440 million years ago."
Professor Gabbott and her team spent 25 years studying the fossil before officially naming it Keurbos susanae in a paper published recently in the journal Wiley.
The fossil belongs to an ancient group of marine arthropods, distant relatives of today’s shrimps, lobsters, spiders, mites, millipedes and centipedes.
The remains were found in strata that settled on the seafloor over 440 million years ago, a period when over 85% of Earth's species had just been wiped out in a devastating glaciation event.
The ocean where Sue once swam was a harsh place, filled with toxic hydrogen sulphide – Professor Gabbott thinks this chemical soup helped preserve her soft insides in incredible detail.
This type of preservation is so rare that it makes it difficult to compare Sue with other fossils from the same era – it therefore remains a mystery how she fits into the evolutionary tree of life.
The small quarry where Sue was discovered is now almost gone, and no other specimens have been found, says Professor Gabbott.
"This has been an ultramarathon of a research effort. In a large part because this fossil is just so beautifully preserved there’s so much anatomy there that needs interpreting. Layer upon on layer of exquisite detail and complexity.
"I’d always hoped to find new specimens but it seems after 25 years of searching this fossil is vanishingly rare – so I can hang on no longer. Especially as recently my mum said to me ‘Sarah, if you are going to name this fossil after me, you’d better get on and do it before I am in the ground and fossilised myself’.
“I tell my mum in jest that I named the fossil Sue after her because she is a well-preserved specimen! But, in truth, I named her Sue because my mum always said I should follow a career that makes me happy – whatever that may be. For me that is digging rocks, finding fossils and then trying to figure out how they lived what they tell us about ancient life and evolution on Earth.”
Find out more about the study: A new euarthropod from the Soom Shale (Ordovician) Konservat-Lagerstätte, South Africa, with exceptional preservation of the connective endoskeleton and myoanatomy
Main image: Cederberg Mountains in South Africa – the landscape where the fossil was discovered. Credit: Getty
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