BRODIOPTERA S TRICKLA NI N . SP. 
(MEGASECOPTERA: BRODIOPTERIDAE), 
A NEW FOSSIL INSECT FROM THE UPPER 
MANNING CANYON SHALE FORMATION, UTAH 
(LOWERMOST NAMURIAN B) 
By C. Riley Nelson 1 and William D. Tidwell 2 
The insect described in this report was collected from the upper- 
most units of the time-transgressive unit — the Manning Canyon 
Shale Formation, in central Utah. This formation of Late Missis- 
sippi to Early Pennsylvanian (Namurian A and B) age consists 
predominately of shales with interbedded limestones, orthoquartz- 
ites and some siltstones. A flora has been described from the upper 
portion of this formation at and near the collecting site for this 
insect. The flora from the upper Manning Canyon Shale, as 
presently defined, contains 43 genera and 103 species (Tidwell, 1967; 
Tidwell et al., 1974; Webster et al., 1984). Thus, it represents the 
most diversified flora of Carboniferous age presently known in 
western North America. Plant fossils from this formation consist of 
fern or fern-like foliage, lycopods, species with calamitean affinities, 
various seed types, cordaitean taxa and several forms related to 
microsporangiate structures. These plants indicate that the area was 
a swampy, moist lowland with perpetual summer-like conditions 
(Tidwell, 1975). 
The Manning Canyon Shale is the oldest horizon reported to be 
insect-bearing in western North America (Durden, 1984). The age of 
the uppermost Manning Canyon Shale Formation remains uncer- 
tain. Many paleontologists and geologists consider the formation to 
be entirely Mississippian (Upper Namurian A: Bissell, 1959; Gordon 
and Duncan, 1970; and Webster et al., 1984). Others (Chamberlain 
and Clark, 1973; Sando, 1985) place the base of the formation in 
Upper Mississippian and the upper portion in the Lower Pennsyl- 
vanian (Namurian B and C). The majority of the fossil plants from 
the upper shales of this formation are encountered only in the Penn- 
1 Department of Zoology and department of Botany and Range Science, Brigham 
Young University, Provo, Utah 84602. 
Manuscript received by the editor June 10, 1987. 
309 
