(Dawn Plectreurys - after the Plectreurys genus of spiders).
Named By: Paul A. Selden & Diying Huang - 2010.
Classification: Arthropoda, Arachnida, Araneae, Araneomorphae, Plectreuridae.
Species: E. gertschi (type).
Size: Body length about 3 millimetres long, leg span roughly estimated about 8-9 millimetres.
Known locations: Mongolia - Daohugou Beds.
Time period: Callovian of the Jurassic.
Fossil representation: At least seven individual spiders.
was (and at the time of writing still is) at the time of its
description to be the oldest known Haplogynae spider, the genus going
back as least as far as the mid Jurassic, while previous examples
were only known as far back as the early Cretaceous. This group of
spiders is identified by studying the female genitalia, which in the
Haplogynae are not sclerotized (hardened). The name Eoplectreurys
is derived from the similarity of this ancient spider to the modern
extant (still alive) genus Plectreurys. This
Eoplectreurys assigned to the Plectreuridae group of
spiders that today
are only known to live in arid desert-like environments of North
America (particularly the Western United States and Mexico) as well
as some Caribbean Islands.
The number of eyes of Eoplectreurys is unknown, but since it is so similar to the plecteurid spiders in other ways, it may have had eight like them too. If so then this would be also interesting since most of the Haplogynae actually have six eyes, with some having as few as four eyes. As far as sexual dimorphism is concerned, male Haplogynae spiders tend have a round carapace (the hard upper shell of the thorax), while the females have an elongated carapace. Out of the seven known individual Eoplectreurys at the time of their description, only one had a round carapace.
With a body length of three millimetres, a single Eoplectreurys could comfortably sit on your fingernail with room to spare. It should be remembered however that this small spider was still a predator, though one that probably hunted other small invertebrates. Assuming that it also had a similar lifestyle to its modern extant relatives, Eoplectreurys might have lurked under rocks and other hard cover while waiting for ground dwelling invertebrates to pass by.
Another Jurassic era spider from the Mongolian Daohugou Beds is Nephila jurassica.
- The oldest haplogyne spider (Araneae: Plectreuridae), from the Middle Jurassic of China, Paul A. Selden & Diying Huang - 2010.