Czech scientists have found unique specimens of trilobites that suggest something thought to be impossible – something was eating them. The small animals were amongst the most successful in history, crawling along the seabed for more than 270 million years. But during the Cambrian era, 500 million years ago, when neither fish nor cephalopods had developed, there should have been nothing capable of sinking its teeth into their hard shells. At a recent conference of international palaeontologists in Prague, Dr Oldřich Fatka of the Institute of Geology and Palaeontology presented evidence from more than thirty years of study, showing that even 508 million years ago there seems to have been a predator on the sea floor.
“Our research focused on specimens that showed specific features: there are, in some rare cases, preserved traces of attacks on the trilobites. So, in our presentation we showed about eight of the twelve available specimens that show attacks from the right or left side, just behind the head. There, three to six thoracic segments are missing, and these are the traces of the attack. The attacks were lethal, killing the trilobite. These specimens showing attacks are very spectacular because the animals which are usually the supposes eaters and attackers of trilobites are still absent in Cambrian rock.”
Do we have any idea what such a predator might have looked like?
“There were no fish, no cephalopods at that time. We have some speculative ideas, for instance the so-called anomalocaridids. Anomalocaridids are a group that is outside of our recent systems of biology. They are very typical of the Cambrian sediments, and they are interpreted as planktonic, or benthic, animals, reaching very large dimensions for their time – more than 100 centimetres in length. And they are interpreted by some authors as potential scavengers and even animals that were able to attack other living organisms. Therefore, we suppose that one of the candidates for the animals responsible for the wounds on the trilobites are anomalocaridid-like animals, some smaller form than the typical genus that were benthic – meaning they did not swim well but crawled above the water sediment interface and tried to find something to eat. So one of the potential animals are anomalocaridid-like types of organisms.”
Where does your research go from here and how will you clarify the situation?
“We will try to find more wounded trilobites to see, for instance, if already at that time there was a preference for the right or left side (about 20 years ago it was discussed that the Burgess shale showed a preference for the right side). So we will try to find the animals that could have been responsible for these attacks, even in the Czech Republic. We are not sure if we will be successful, because these organisms that are supposed to be the attackers, were not well skeletonised – meaning they are very rarely preserved, not only here but worldwide. So we have some traces that could be interpreted as an anomalocaridid-like animal, but we would like to find more, and we would like to find more in layers in which the wounded trilobites occur. In that case we could say ‘okay, here we have the most probably guys responsible for the attacks’.”