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Psyche 
[March 
absence of Vespidae from Baltic Amber (Lower Oligocene) and 
other fossil resins, in which ants are abundant, is probably due to 
their relatively large size, which reduces the likelihood of their 
entrapment in the sticky tree resin. Spradbery (1973, p. 316), 
attributes their scarcity in sedimentary deposits to “the behavioral 
characteristics and paper nest structures which do not lend them- 
selves to fossilization.” As with any other fossil, the absence of an 
insect in the paleontological record provides no proof as to its actual 
occurrence in the past; one can only reconstruct and evaluate 
paleofaunas on the basis of those organisms that are represented. 
Therefore, it is conceivable that wasps were present earlier than the 
record indicates, but that conditions conducive to their preservation 
were lacking. The following does, however, provide information on 
the diversity of the group as we know it. 
Cretaceous 
The earliest record of the Vespoidea extends back to the Upper 
Cretaceous (Turonian). Two species of vespoid wasp have been 
found in a deposit of this age in the USSR — both assigned to 
the genus Curiovespa (Rasnitsyn, 1975). Unfortunately, nothing is 
known about the body structure of these insects but on the basis of 
their wing venation they are placed in the family Masaridae. The 
presence of two distinct species in the same deposit suggests that some 
diversification of the Vespoidea had taken place as early as the Upper 
Cretaceous, although nothing is known about the morphological 
character of these early wasps. 
Paleocene 
No Vespoidea from this period are known. 
Eocene 
The Eocene beds of Green River have yielded a surprisingly 
diverse assemblage of aculeates, but most of these belong to the 
Terebrantia or Sphecoidea; the only vespoid recovered from this 
deposit, Didineis solidescens, is of uncertain systematic position 
(Evans, 1966, p. 393). Scudder (1890) described this specimen as a 
sphecid of the subfamily Nyssoninae. However, Evans (1966) 
examined the type and concluded that it did not belong to the family 
Sphecidae, but was probably a eumenid, and tentatively assigned it 
to the genus Alastor. 
