Ancient Arthropod Preserved in Amber
A rare relative of spiders has been discovered preserved in 40 million year old amber. The little creature was trapped in pine resin and preserved with the resin eventually turning into amber. This rare specimen identified as a Harvestman (Dicranopalpus ramiger), has been donated to the London Natural History Museum (United Kingdom).
The amber, which was from the Baltic area dates from the Late Eocene, amber of this age and from the Baltic is fairly common but to find such a rare and complete specimen so well-preserved is a very special event. It seems that around 40 million years ago, a tiny Harvestman climbed up a pine trunk, encountered a lump of thick, sticky tree sap and was engulfed. The whole animal was trapped, a set of events leading to the preservation of this relative of true spiders for scientists to study.
Sent to a Museum for Further Study
A Rochester-based fossil collector (Rochester in Kent, England); had purchased a number of amber pieces on an on-line auction website, on receiving the goods, a close examination of the amber revealed a tiny leg hiding in one piece. He carefully polished it and slowly removed some layers to reveal the complete fossil of this tiny forest inhabitant of the Cenozoic. Realising he had found something unusual the specimen was sent to the London Natural History museum for expert analysis.
One of the Museum’s Collection Managers, the person responsible for cataloguing fossilised invertebrates and plants studied the specimen very carefully using a powerful microscope. It was this scientist who identified the Arthropod as a type of Harvestman (spider-like animal).
Harvestmen belong to the Arachnid class, the earliest fossil Harvestmen date from the Lower Carboniferous deposits from East Kirkton, Scotland. A fossil Harvestman from these deposits, an Opilonid has been dated to around 320 million years ago, although these creatures may have existed even earlier, perhaps being some of the first creatures to adapt fully to a terrestrial lifestyle.
Today there are around 26 species of Harvestmen in the United Kingdom. They may look like spiders with their eight legs but this is only a superficial similarity. Harvestman have no silk glands, they cannot spin silk, they have not got the ability to defend themselves with a poisonous bite, their only means of defence in most species is to produce a foul-smelling chemical to put off a would be attacker.
Spiders have a segmented body, with a head, thorax and abdomen clearly divided. Harvestmen have a fused body with no body segments. The palaeontologists who have studied the ancient fossil have declared that this specimen is the remains of a very young Harvestman, the specimen has a body about the size of a pin head and eight legs, each around six millimetres in length.
What really excites the researchers, all specialists in ancient invertebrates is that all of the eight legs of this Arachnid are still intact. None have been lost as the creature struggled to escape. This tiny creature must have been engulfed and overwhelmed by the tree resin very quickly. Finding such a complete specimen of a tiny prehistoric creature is a very rare event in palaeontology.