By Richard Gray, Science Correspondent, The Telegraph, UK
Scientists working at Oxford University found tiny threads of spidersilk encased inside a piece of amber that formed around 140 million years ago. The web appears to be similar to those of modern orb web spiders, which weave a spiral web of silk to catch insect prey. The discovery suggests that orb web spinning spiders existed far earlier than had been previously thought, at a time before flowering plants appeared on the planet and triggered an explosion in flying insects.
The scientists believe the web became trapped in conifer resin in the aftermath of a forest fire and then became fossilised inside the resulting amber. They hope that by studying other pieces ofamber from the same deposits they may learn more about spiders from that time and the prey they ate.
Professor Martin Brasier, a palaeobiologist at Oxford University who led the study, said: “It is absolutely consistent with an orb web spider. The spacing between the threads suggest they were the structural struts onto which a web was spun.
“The treads themselves are made of two pieces joined together just like a modern web. The spider spins the threads from two spinnerets at its back and twirls them together. The amber flow appears to have cut across the web and embalmed it. “We have also found a few tangles of web in the amber. It is amazing to see something so delicate that has survived so many million years.” The amber was found on a beach famous for fossilised dinosaur tracks near Bexhill, in East Sussex, by amateur fossil hunter Jamie Hiscocks.
He took the amber to Professor Brasier and his student Laura Cotton, who will reveal their findings at the annual meeting of the Palaeontological Association in Glasgow this week. Using advanced microscope techniques, the scientists were able to peer into the amber to build up a picture of what was inside. By merging 40 image slices taken through the amber, they discovered threads of spider web each more than a millimetre in length.
Pieces of charred bark and burnt sap inside the amber suggest the trees that produced the fossilised resin had been damaged in a fire and produced the droplets of resin to protect itself from infection. Fossilised charcoal was also found in the fossil beds near to the amber along with fossilised tracks of Iguanodon, large plant eating dinosaurs.
Until now the oldest known spider web was found in 130-million-year-old amber discovered in Lebanon and the earliest fossilised orb spider was found in a fragment of amber 120-million-years-old. This latest discovery proves that the web-spinning arachnids were around millions of years earlier still. Delicate structures like spider webs are not normally fossilised and can only be preserved if they have been caught up in resin such as amber.
Professor Brasier said: “The amber appears to have been flowing through lower parts of the trees near to the ground so we can imagine little cobwebs forming in the very lower parts of the tree trunk. “Webs are used to catch things flying through the air and we know that all sorts of insect groups were starting to become quite adept at flying at this time. Many of the modern fly group, mosquitoes, bees and wasps all take off at this time.
“These webs were around in a conifer dominated world before flowering plants, but it is clear it was already gearing up for the huge diversity of flowers brought with them. The spiders appeared to be keeping up with the other evolutionary patterns in the insects.”
Ancient amber deposits more than 100-million-year-old are extremely rare and scientists hope the Bexhill amber will reveal yet more secrets. The amber deposit, which is hidden beneath the tide for much of the time, is also believed to be the first significant amber deposit in Britain. Most famous amber deposits have been found in France, Germany, the Caribbean and Lebanon.
Amber deposits, which form from fossilised tree resin, have attracted intense public attention in the wake of the hit film Jurassic Park where scientists used dinosaur blood extracted from mosquitoes preserved in amber to clone dinosaurs.
Dr Samuel Zschokke, an expert in ancient spider webs at Basel University, Switzerland, who discovered the 130-million-year-old spider web in Lebanese amber, said: “This sounds rather exciting. It appears that a new record has been set. “Spider silk probably evolved back inthe Devonian period and it has probably been used to build webs for some 200 million years. The limiting factor for the oldest fossil spider silk is not the occurrence of silk at these early times but the existence of fossil bearing amber.”