Rock Bristletail – Family Meinertellidae
Order Microcoryphia or Archaeognatha
Live adult bristletails photographed in the wild at northern Illinois, USA. Size: 15mm (body only)
These specimens were found living in an outcrop of Ordovician dolomite and sandstone at Lowden State Park near the Rock River in Oregon, Illinois.
The bristletail lineage is ancient. Earliest fossil evidence of such creatures appear in Devonian rocks about 390 million years old.
The Ordovician sedimentary rocks this specimen lives in are about 450 million years old, deposited in near-shore or marine environments.
At this time, Illinois lay in the tropics south of the equator; a warm, shallow sea alternately flooded and receded for millions of years [3].
Bristletails are insects with six legs; in addition, abdominal segments 2-9 each bear a pair of a styli – short, stiff appendages moveable by muscles. These may be vestigial remnants of ancestral limbs [2].
Specialized abdominal musculature gives bristletails the ability to jump away from danger by snapping the abdomen and the whip-like medial filament against the substrate.
References
- Bugguide.net, “Order Microcoryphia – Bristletails“
- Tree of Life, “Archaeognatha – Bristletails“
- Special thanks to Mary J. Seid, Illinois State Geological Survey for her bedrock maps of the Oregon and Mt. Morris quadrangles in Illinois.
Tree Encyclopedia / North American Insects & Spiders
Online since 2002
