First record of the spider family Araneidae from the Lower Cretaceous
MANCHESTER: The world's oldest orb web-spinning spider has been found, perfectly preserved in an ancient piece of amber. The spider, 2 mm long, is the oldest example of a spider to have spun the vertical orb-shaped spider web found in homes and gardens.
It is between 115 and 121 million years old. For the first time, it dates the orb web-spinning spider family Araneidae back to the Lower Cretaceous period. It also confirms the orb-web as one of the oldest structures used by spiders to capture prey.
Until now, the oldest recorded orb web-spinning spider dated back to the Upper Cretaceous period (the 94-million-year-old New Jersey amber).
Dr. David Penney, of the University of Manchester's School of Earth Atmospheric and Environmental Sciences, who also holds the record for unearthing the oldest spider trapped in amber (135 million years old), found the fossil in a museum in Spain.
He said: "This find provides the first evidence that all major orb-weaving families had evolved by the Lower Cretaceous period and demonstrates that this prey capture strategy was already well evolved at a time when many of a spider's prey like flowering plant pollinating insects did not exist."
Dr. Penney was able to identify it by examining the eye arrangement, tarsal claw structure and reproductive organs.
This is the first record of the spider family Araneidae from the Lower Cretaceous and provides the first evidence that all three major orb web-spinning spider families (Araneidae, Tetragnathidae and Uloboridae) had evolved by this time. Dr. Penney's results are contained in a paper: "Oldest true orb-weaving spider (Araneae: Araneidae)," published in the Royal Society's Biology Letters.