Phasmid
Insect
Early Eocene
Green River Formation
Rio Blanco, Colorado, USA

41mm phasmid including huge antennae on 74mm slab. Extremely rare

Arthropod. Insect. Orthopteran.

Walking sticks (phasmids) or stick insects are insects that date back at least to the Late Jurassic. They belong to the Order Orthoptera – relatives of grasshoppers, katydids, and crickets. Fossils are rare but they occur in the Green River Formation (as seen here) and nymphs have been collected in Baltic, Mexican, and Dominican ambers. They have become excellent mimics of twigs and sticks even swaying when a breeze comes through.

Today, walking sticks live in tropical and temperate regions of the continents. They must have spread out across the world as the continents separated and drifted apart during the Mesozoic and Cenozoic. 

It turns out you can evade extinction for over 150 million years if you have a good disguise.