Enigmatic Cambrian fossil
Chengjian Lagerstatte,in China is a fossil paradise discovered in 1984 that has been dated to the Lower Cambrian period, 525 million years ago, making it around 10 million years older than Canada’s famous Burgess Shale.Recently Derek Siveter of the Oxford University Museum of Natural History along with a Chinese group unearthed an enigmatic fossil which exhibit group behaviour ,which is mostly unknown in modern invertebrates and has never been demonstrated in fossil invertebrates.This new species of Early Cambrian arthropod formed sturdy chains comprising of around 20 individuals,where one animals tail is inserted into the carapace of another.
Image of Burgess Shale in canada
“Of the millions of fossils, the chances of getting an occurrence where we can determine collective behavior is quite rare,” — Derek Siveter
Modern day animals like spiny lobsters in the Caribbean are known to display collective behaviour ,where in the antennae of one lobster grasp the carapace of the next individual in line. This behaviour is thought to aid in feeding, molting or migration following a storm.But the difference with this early cambrian fossil from Chengjian Lagerstatte is that they look almost unbreakable ,showing signs of twisting, turning, and bending.The authors are of opinion that these fossil chains may have floated in the early Cambrian ocean.
The most important question comes to mind is why these arthropods formed chains?
Forming chains for feeding is ruled out as mouth of one animal is covered by tail of the one ahead of it and its also unlikely that they had some advantage for reproduction by forming chains
The exact answer is difficult to know at this moment but researchers are of the opinion that by migrating in chains may have provided these animals protection against predators especially when they are on long journeys.
For related news and images of this enigmatic arthropod of cambrian age visit sciencenews
Reference :
Collective Behavior in an Early Cambrian Arthropod
Xian-Guang Hou, Derek J. Siveter, Richard J. Aldridge, David J. Siveter
Science 10 October 2008:Vol. 322. no. 5899, p. 224
DOI: 10.1126/science.1162794
Image Details:
Burgess Shale in canada
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