1978] 
Burnham — Social Insects in Fossil Record 
117 
is so highly polyphyletic remains unanswered, and is a problem 
unlikely to be resolved by the geological past. 
However, the fossil record does provide intriguing information on 
the evolution of the bees and indicates that their sociality may well 
have been established prior to the Oligocene. The following survey 
of the fossil Apoidea is indicative of the diversity of bees which have 
been found (Table 5). Those species which were described by early 
19th century entomologists (Latreille, Heer, Heyden, etc.) are 
excluded from this coverage because these were uniformly assigned 
to modern genera. 8 Cockerell (1909) claims that most of these 
species actually belonged to quite different and extinct genera. 
Oligocene 
The earliest bees in the fossil record are found in the Baltic 
Amber, of Lower Oligocene age. The bees in this deposit are well- 
diversified (Zeuner and Manning, 1976), and the most prevalent 
apoid genus in the amber, Electrapis, is thought to have been social. 
Cockerell (1909) based this conclusion on the occurrence of many 
specimens of Electrapis meliponoides crowded together in a small 
piece of amber, a suggestive but certainly not conclusive deduction. 
Zeuner (1944, 1951), however, believed Electrapis to be social based 
on its pollen collecting apparatus. The extent to which social 
behavior was developed in this genus nevertheless remains a matter 
of conjecture. Electrapis is considered by some to be directly 
ancestral to the highly eusocial Apis, although Kelner-Pillault 
(1974) disagrees with this relationship. She suggests that Electrapis 
is actually a long extinct genus which possessed many primitive 
characters and represents an evolutionary side-line of the Apoidea. 
Both hypotheses are highly conjectural. 
The presence of long-tongued bees such as Electrapis suggests 
that the Baltic Amber bees were rather specialized. Tongue structure 
is assumed to have evolved in response to various morphological 
changes (i.e., longer corollas) which took place during the evolution 
of the angiosperms (Michener, 1974). Short-tongued bees such as 
the colletids are considered the more primitive members of the 
Apoidea and are representative of bee radiation that occurred at a 
time when most of the angiosperms had shallow flowers (Michener, 
1974). 
For a listing of these specimens, see Zeuner and Manning (1976). 
