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Last Updated: Thursday, 7 August, 2003, 10:23 GMT 11:23 UK
Oldest spider silk found
The oldest known strand of spider silk has been found, preserved in Lebanese amber.

Silk, Nature
The glue globules designed to stick down prey are clearly visible
It dates from the Early Cretaceous Period, more than 120 million years ago.

This means it comes from about 80-90 million years further back in time than the previous oldest reported spider thread, found in Baltic amber.

The specimen is described in the journal Nature by Swiss researcher Dr Samuel Zschokke, from the University of Basel.

Small globules of glue that would have stuck down any insect unlucky to get caught up in the silk are still clearly visible on the thread.

Primitive organisms

Amber is a form of protective resin extruded from trees that has hardened over millions of years.

It is very useful to scientists studying the history of past life because ancient animals and plants are often preserved in the gem-like material. This is particularly true of arthropods like insects and spiders.

The oldest known spider found in a piece of amber was unearthed on the Isle of Wight in the UK recently.

But the 125-million-year-old creature, Cremygale chasei, is by no means the earliest in the fossil record. There are specimens that date from the Devonian (350-420 million years ago) - long before even the dinosaurs.

And in some of these mineral fossils, it is possible to see evidence of spinnerets, the organs spiders use to spin their web silk.

The newly reported specimen was actually recovered in 1969 from amber beds located near Jezzine in Lebanon - but its importance has only recently been recognised.

Time limit

The preserved strand is just four millimetres in length and bears tiny glue droplets, which in modern-day spiders are produced by a spider's silk-producing glands to form an adhesive coating around the fibre.

Dr Zschokke says the diameter of the ancient thread, and the size, density and arrangement of the droplets closely match those in webs made by recent araneoids - the superfamily that today includes common garden spiders that spin ornate, spiral orbs.

But Dr Zschokke adds: "As the specimen contains only a single thread, we cannot identify with certainty the type of web of which this thread was a part.

"It may have been part of an orb-web or of a gum-footed web. However, the fossil thread could have been part of a web type that no longer exists today.

"In any case, the present specimen is direct evidence for the antiquity of viscid spider silk."

It is certainly the oldest example of spider silk on record - and it may be hard to beat. Experts say the time period is pushing at the limit for amber preservation and mineral fossils would not retain the details of a spider's web.




SEE ALSO:
Spider scientists spin tough yarn
10 Aug 03  |  Science/Nature
Parasite's web of death
19 Jul 00  |  Science/Nature


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