Nav: Home

Fossils found reveal unseen 'footprint' maker

January 16, 2017

Fossils found in Morocco from the long-extinct group of sea creatures called trilobites, including rarely seen soft-body parts, may be previously unseen animals that left distinctive fossil 'footprints' around the ancient supercontinent Gondwana.

The trilobites were a very common group of marine animals during the 300 million years of the Palaeozoic Era with hard, calcified, external armour-like skeletons over their bodies. They disappeared with a mass extinction event about 250 million years ago which wiped out about 96% of all marine species.

University of Adelaide-led research published in the journal Scientific Reports describes three specimens of the 480 million-year-old trilobite Megistaspis (Ekeraspis) hammondi, up to 30 centimetres long and with preserved soft-parts showing a unique combination of digestive structures and double-branched legs.

"One of the most striking aspects of the discovery is that the first three pairs of legs, those located in the head, bear short, strong spines, while those further back in the thorax and tail are smooth," says Dr Diego García-Bellido, ARC Future Fellow with the University of Adelaide's Environment Institute and South Australian Museum.

"We believe this specialised type of legs are the ones that produced the fossil traces named Cruziana rugosa, thought to be from a trilobite but the actual trace-maker was previously unknown. These marine animals ploughed the sediment in the sea floor for food with their forward legs, while holding their heads tilted downward, leaving behind a double groove with parallel scratches made by the spines on the legs.

"The legs we can see on these new fossils match the traces we've known as Cruziana rugosa."

Dr García-Bellido, Juan Gutiérrez-Marco of the Spanish National Research Council and colleagues present for the first time the preserved gut with associated digestive structures plus a complete set of both branches of the trilobite legs.

Cruziana species are one of the most abundant trace fossils found in the lower Palaeozoic sediments across Gondwana but little was known of the particular process producing the distinct Cruziana rugosa traces, where imprints are aligned in sets of up to 12 parallel scratches.

The digestive structures seen also include a unique combination of features: a 'crop' together with several pairs of digestive glands or caeca in the upper parts of the digestive system. Other trilobite fossils have been seen with either a crop or the paired digestive caeca but, until now, they have never been found together.

Trilobites have three main parts: a head with eyes, antennae, mouth, and three pairs of appendages or legs; a thorax with many joined segments, each bearing a pair of legs; and a tail with a number of fused segments and several pairs of legs. Trilobite appendages are soft, with an outer branch which is a gill, and an inner branch used for walking and feeding. The preservation of their soft-body is extremely rare, restricted to only a couple of dozen cases, because their external 'skin' and internal anatomy was normally lost through scavenging and decay soon after death, or overprinted by the mineralised exoskeleton.

The research involved collaboration between the University of Adelaide/South Australian Museum, the Spanish Research Council and Spanish Geological Survey, and the Universities of Vila Real and Coimbra in Portugal.
-end-
Media Contact:

Dr Diego García-Bellido, ARC Future Fellow, Environment Institute, University of Adelaide. Phone: +61 (0)8 83134870, Mobile: +61 (0)404 426 249, diego.garcia-bellido@adelaide.edu.au

Robyn Mills, Media Officer, Phone: +61 (0)8 8313 6341, Mobile: +61 (0)410 689 084, robyn.mills@adelaide.edu.au

University of Adelaide

Related Marine Animals Articles:

Why are there no animals with three legs?
If 'Why?' is the first question in science, 'Why not?' must be a close second.
What color were fossil animals?
Dr. Michael Pittman of the Vertebrate Palaeontology Laboratory, Department of Earth Sciences, The University of Hong Kong led an international study with his PhD student Mr.
88% decline of big freshwater animals
Scientists from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) and international colleagues have now quantified the global decline of big freshwater animals: from 1970 to 2012, global populations of freshwater megafauna declined by 88% -- twice the loss of vertebrate populations on land or in the ocean.
Animals may have more than one means of surviving hypoxia
A tidepool crustacean's ability to survive oxygen deprivation though it lacks a key set of genes raises the possibility that animals might have more ways of dealing with hypoxic environments than had been thought.
Deceptively simple: Minute marine animals live in a sophisticated symbiosis with bacteria
Trichoplax, one of the simplest animals on Earth, lives in a highly specific and intimate symbiosis with two types of bacteria.
More Marine Animals News and Marine Animals Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...