1967] 
Wilson , Carpenter , Brown — Mesozoic Ants 
17 
Our analysis of Sphecomyrma, incomplete as it must be, neverthe- 
less suggests several promising lines of investigation in the future. 
First and foremost, of course, is the search for more Cretaceous ants 
and allied aculeate groups. Perhaps the Magothy amber will yield 
more material of interest. Second, we should pay closer attention in 
the future to comparisons in morphology, physiology, and behavior 
between the primitive myrmecioids and primitive poneroids. Dif- 
ferences should be related to the emerging new form of the formicid 
cladogram, while similarities should be examined with reference to 
the question of whether they are monophyletic or convergent. Finally, 
as a better idea is formed of the relationships of the ants to certain 
living wasp families, the biology of the latter needs to be examined 
more closely for clues concerning the origin of social life in ants. 
Acknowledgements 
We gratefully acknowledge the splendid cooperation of Mr. and 
Mrs. Edmund Frey, as well as the intermediary aid of Dr. Donald 
Baird of Princeton University and Mr. David Stager of the Newark 
Museum. Our separate research programs, within which the analysis 
of Sphecomyrma was undertaken cooperatively, have been supported 
by grants from the National Science Foundation: NSF GB-5574X 
(Brown), NSF GB-2038 (Carpenter), and NSF GB-1634 (Wil- 
son) . 
Summary 
Two worker ants preserved in amber of Upper Cretaceous age 
(Magothy Formation) have been found in New Jersey. They are 
the first undisputed social insect remains of Mesozoic age, and extend 
the existence of social life in insects back to approximately 100 million 
years. They are also the earliest known, certainly assignable aculeate 
Hymenoptera. The species, Sphecomyrma freyi , is considered to 
Explanation of Plate 4 
A comparison of the archetypal ant as hypothesized by the authors before 
the discovery of Sphecomyrma (e.g., Brown, 1954; Brown and Wilson, 1959), 
with Sphecomyrma itself. The fine details of body shape are made the same 
in this drawing for convenience but do not enter into the main features to 
which phylogenetic speculation has been directed. This comparison is pre- 
sented to indicate the degree of precision of earlier phylogenetic reasoning. 
Examination of the Sphecomyrma specimens proved the hypothesis wrong 
in essentially only one major respect: we had guessed that an ant-like 
mandible developed before an ant-like petiole, but the reverse proved to be 
the case. 
