Two ancient types of harvestmen, or 'daddy long legs,' which skittered around forests more than 300 million years ago, are revealed in new three-dimensional virtual fossil models published today in the journal Nature Communications.
An international team, led by researchers from Imperial College London, have created 3D models of two fossilised species of harvestmen, from the Dyspnoi and Eupnoi suborders. The ancient creatures lived on Earth before the dinosaurs, in the Carboniferous period. The 3D models are providing fresh insights into how these ancient eight-legged creatures, whose 1cm bodies were the size of small buttons, survived in the Earth's ancient forests and how harvestmen as a group have evolved.
Other scientists have previously suggested that harvestmen were among the first groups on land whose bodies evolved into their modern-day form at a time while other land animals such as spiders and scorpions were still at an early stage in their evolution. The researchers say comparing the 3D fossils of the Dyspnoi and Eupnoi species to modern members of these harvestmen groups provides further proof that ancient and modern species were very similar in appearance, suggesting little change over millions of years.
Dr Russell Garwood, who is currently based in the computed tomography lab at the Natural History Museum in London and who carried out his research while at the Department of Earth Science and Engineering at Imperial College London, says:
"It is absolutely remarkable how little harvestmen have changed in appearance since before the dinosaurs. If you went out into the garden and found one of these creatures today it would be like holding a little bit of prehistory in your hands. We can't yet be sure why harvestmen appear so modern when most land animals, including their cousins such as scorpions, were in such a primitive form at the time. It may be because they evolved early to be good at what they do, and their bodies did not need to change any further."
The 3D virtual fossil models have also provided the researchers with further proof that the Dyspnoi and Eupnoi lineages had evolved from a common harvestmen ancestor around 305 million years ago. The researchers say their work supports earlier DNA-based studies and is important because it provides a clearer picture of the early evolution of these creatures.
The researchers also found clues as to how both creatures may have lived hundreds of millions of years ago. The team believe that the Eupnoi probably lived in foliage just above the forest floor, which may have helped it to hide from predators lurking on the ground. The 3D model of the Eupnoi revealed that it had long legs with a curvature at the end that are similar to the legs of its modern relatives who use the curved leg parts to grip onto vegetation while moving from leaf to leaf.
The researchers also determined that the Eupnoi's body had a very thin and soft outer shell or exoskeleton by analysing a section of the 3D fossil showing a part of its abdomen that had been crushed during the fossilisation process. This indicated to the team the fragility of the Eupnoi's exoskeleton.
The Dyspnoi fossil had spikes on its back and the scientists believe this may have provided it with some protection from predators who would have found the creature a prickly meal to swallow, and that the Dyspnoi may have lived in moist, woody debris on the forest floor. Dyspnoi's modern American descendent Acuclavella cosmetoides also has spikes for protection and lives in similar environmental conditions.
It is rare to find fossilised remains of Harvestmen because their soft, tiny, fragile bodies are difficult to preserve during the fossilisation process. Only around 33 fossilised species have been discovered so far.
Currently, most palaeontologists analyse fossils by splitting open a rock and looking at the creatures encased inside. This means that they can often only see part of a three-dimensional fossil and cannot explore all of the fossil's features.
The method used in today's study is called 'computed tomography' and it enables researchers to produce highly detailed virtual models using a CT scanning device, based at the Natural History Museum in London. In this study, scientists took 3142 x-rays of the fossils and compiled the images into accurate 3D models, using specially designed computer software.
This research follows on from previous modelling studies carried out by Imperial researchers on other prehistoric creatures including ancient spiders called Anthracomartus hindi and Eophrynus prestivicii, and an early ancestor of the cockroach called Archimylacris eggintoni.
The research was funded by a Natural Environment Research Council studentship.
Notes to Editors:
1. Images of 3D models showing the ancient creatures from today's study is available for use
Download image of Dyspnoi: https://fileexchange.imperial.ac.uk/files/cca45a456/Dyspnoi.png
Download image of Eupnoi: https://fileexchange.imperial.ac.uk/files/7f2d66747c/Eupnoi%20lateral%20view.png
2. 3D computer models of Dyspnoi and Eupnoi are available on request. Please contact Colin Smith (details above).
3. " Carboniferous harvestmen demonstrate early cladogenesis and stasis in Opiliones' ",23 August 2011, Nature Communications journal.
The full listing of authors and their affiliations for this paper is as follows:
Russell J. Garwood1, Jason A. Dunlop2, Gonzalo Giribet3 & Mark D. Sutton1
1 Department of Earth Science and Engineering, Imperial College, London SW7 2AZ, UK
2Museum für Naturkunde at the Humboldt University Berlin,D-10115 Berlin, Germany
3Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge,Massachusetts 02138, USA
Link to study: https://fileexchange.imperial.ac.uk/files/4fb9d397a9e/Nature%20Communications%20-%20%20Anatomically%20modern%20Carboniferous%20harvestmen%20demonstrate%20early%20cladogenesis%20and%20stasis%20in%20Opiliones.pdf
2. About Imperial College London
Consistently rated amongst the world's best universities, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 14,000 students and 6,000 staff of the highest international quality. Innovative research at the College explores the interface between science, medicine, engineering and business, delivering practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.
Since its foundation in 1907, Imperial's contributions to society have included the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of research for the benefit of all continues today, with current focuses including interdisciplinary collaborations to improve global health, tackle climate change, develop sustainable sources of energy and address security challenges.
In 2007, Imperial College London and Imperial College Healthcare NHS Trust formed the UK's first Academic Health Science Centre. This unique partnership aims to improve the quality of life of patients and populations by taking new discoveries and translating them into new therapies as quickly as possible. Website: www.imperial.ac.uk
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