Original description: Test conical, without horn, with five to six post-abdominal chambers. Cephalis conical, remaining chambers trapezoidal in outline and gradually increasing in width as added. Earlier chambers closely spaced, sparsely perforate, covered with layer of microgranular silica. Post-abdominal chamber consisting of two to three rows of polygonal pore frames in each chamber. Final post abdominal chamber terminating in largesubspherical expansion. Pore frames subregular, slightly variable in size, with largest pore frames on bulbous expansion. Test without prominent circumferential ridges, with H-linked pattern along joints.
Etymology: Megaglobosa: mega (large) globosus-a-um (spherical).
Full reference: K. Y. Yeh. 1987. Taxonomic Studies of Lower Jurassic Radiolaria from East-Central Oregon. National Museum of Natural Science Special Publications 2:1-169
Type specimen: NMNS (000153). Its type locality is Suplee-Izee area, OR-600A, which is in a Toarcian marine tuff/limestone in the Hyde Formation of Oregon.
Ecology: passively mobile planktonic omnivore