1978] 
Burnham — Social Insects in Fossil Record 
91 
Simpson (1952) has made some insightful remarks on the matter. 
He contests the premise that if a given group of organisms requires a 
land connection, then disjunctive areas occupied by the group must 
have been once connected by continuous land. His contention is 
that there is no group of organisms that cannot be dispersed over 
water. Given a probability of only one chance in a million that an 
organism can cross a stretch of water, when geological time is 
considered the chance that the event will actually take place (over 
tens of millions of years) becomes significantly greater. It is further 
argued that successful colonization is dependent on successful 
invasion and the ability of the intruder to compete with existing 
species. Chances for survival are much higher when there are 
numerous, simultaneous arrivals of individuals. 
In my opinion, the termites support such reasoning, and this can 
be argued in several ways. Firstly, termites are relatively light- 
bodied, winged insects. Studies by Simberloff and Wilson (1969) 
and Glick (1933) on the repopulation of an island by wind trans- 
ported insects strongly support the possibility that termites are 
capable of being carried considerable distances in the upper atmos- 
phere. Furthermore, because termites swarm in such large numbers 
prior to reproduction, a reasonable possibility exists that they will 
be dispersed to a new habitat as either a group or at least as a 
male/ female pair. A wind current strong enough to blow one 
individual into the upper atmosphere should be equally capable of 
carrying multiple individuals, and, according to windflow, of trans- 
porting them in the same directional pathway. 
Secondly, termites are ideally suited to dispersal over large bodies 
of water via floating logs. The more primitive families construct 
their extensive nesting colonies in wood and logs; as a consequence, 
it is entirely plausible that a dead tree falling into a body of 
circulating water could be carried extended distances. Furthermore, 
this mode of transportation provides the termites with a source of 
food during their sojourn, and travel en masse obviates the prob- 
lems of reproduction upon arrival. In addition, as Simpson points 
out, the larger the number of individuals, the more likely it is that 
they will be successful competitors in the new habitat. I am not 
presenting this as evidence that the termites did not evolve while the 
earth’s land masses were still contiguous, but am merely pointing 
out the problems in arguing that land dispersal was essential for 
termites. 
