A team of researchers has discovered the fossil of a 305 million year old arachnid which will help scientist to understand more about the early origins of modern-day spiders. This new species was named Idmonarachne brasieri in honor of professor Martin Brasier, University of Oxford, who passed away in December 2014.
Details of the origins of spiders remain limited with little knowledge of their predecessors and noo insights into character acquisition early in their evolution. This fossil was preserved in 3D, which enabled the researchers to investigate its minutes anatomical details. They could make silk, but probably laid it down in sheets, rather than spinning it as modern spiders do. They also had a tail-like structure at the end called a glagellum. Analysis of Idmonarachne brasieri suggests that as the as the spider lineage evolved, the animals lost their tail-like structure, and developed spider-like fangs limbs. Whilst they could likely make silk, the ancestors lacked the ability to spin it using specialized appendages called spinnerets. These are the features that define true spiders, and give them more control over the use and distribution of silk.
This is part of an ongoing effort to look at early arachnids and see what this can tell us about the early evolution of the group how they came onto land and what their evolutionary tree looks like. Arachnids as a whole are a very diverse group but working out how they are all related to each other has proved a challenge.
Source: Royal Society
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