Tuesday, June 14, 2016

Fossil dragonfly nymph from California

Dragonfly nymphs have an aquatic existence for a short time before morphing into winged adults. Nymphs live in lakes and streams and are voracious carnivores. Although it would seem that the muddy and quiet burial environment on the bottom an ancient lake would have resulted in nymphs being commonly preserved, their remains in the fossil record are uncommon.

The specimen shown below is a carbonized impression of dragonfly nymph of Pliocene age (approx. 4 million years old) from an ancient lake just north of Los Angeles in southern California.

The specimen is the dorsal view of a carbonized impression of a dragonfly nymph (nearly 35 mm long = nearly 1.5 inches) belonging to family Libelluidae? (genus cannot be determined). It has its antennae (barely visible), left-eye area, both wing pads (probably broken), legs, and posterior spines preserved.

Burial of this specimen must have been rapid, otherwise scavengers would have obliterated the remains.

The specimen was found in a shale bed with associated fish and plant remains (aquatic reedlike plants and nodules of presumably seed-pod origin). 

No comments:

Post a Comment