94 
Psyche 
[March 
Parasitica; the other division within this suborder is the Aculeata. 4 
Members of the latter are characterized by modifications of the 
ovipositor that have enabled its use not only for oviposition, but 
also as a transport vessel for defensive and prey-paralyzing com- 
pounds. This structure unquestionably plays an important role in 
colony defense and might provide an explanation for the restriction 
of eusociality within the Hymenoptera to the Aculeata. 
The oldest known aculeate hymenopteron, Cretavus sibericus, was 
discovered in an Upper Cretaceous (Cenomanian) deposit in Siberia 
in 1957. Although placed by Sharov (1962) in an extinct superfamily 
Cretavidea, related to the Scolioidea, it has recently been transferred 
to the existing family Mutillidae by Rasnitsyn (1977, p. 109). Since 
1967, species representing 10 families and 19 genera of aculeate 
Hymenoptera have been found in Upper Cretaceous deposits in 
Central Asia (Rasnitsyn, 1977) (Table 2). Evans (1966) believes that 
such diversity by the Late Cretaceous is indicative of an earlier origin 
and postulates that the group may have evolved during the Jurassic. 
However, it must be pointed out that the Cretaceous is one of the 
longer periods in the earth’s history, having a duration of roughly 70 
million years, and may have been of sufficient length to account for 
such diversification. 
Vespoidea 
Included in this group are the three families considered to be “true 
wasps”: The Masaridae and Eumenidae, both of which are solitary, 
and the Vespidae, where one finds behavioral modifications ranging 
from subsocial to highly advanced eusocial (Richards, 1953, 1971). 
It is the Vespidae, by virtue of their sociality, with which I am 
primarily concerned in this paper. 
There are many gaps in our record of the early social wasps and of 
the Vespoidea in general. Most striking, perhaps, about the fossil 
record of the wasps is their lack of representation (see Table 3). The 
4 The classification of the Aculeata has recently undergone a major revision by D. J. 
Brothers (1975), in which the seven previously recognized superfamilies (Bethyloidea, 
Scolioidea, Pompiloidea, Formicoidea, Vespoidea, Sphecoidea, and Apoidea) are 
now combined into three: the Bethyloidea, Sphecoidea (subdivided into the Spheci- 
formes and Apiformes), and Vespoidea (subdivided into the Vespiformes and 
Formiciformes). However, since this revised classification has not been generally 
accepted in its entirety, I am employing here the more conventional classification 
(sensu Riek, 1970; Richards, 1971). 
