1967] 
Wilson , Carpenter , Brown — Mesozoic Ants 
15 
social, then the hypothesis of a single origin of social life in ants 
would tend to be supported. 
A cladogram outlining our present best guess at ant phylogeny is 
given in Figure 4. 
Reconstruction of formicid archetype 
Judging from the characteristics of the primitive ants and the 
tiphiid wasps as we know them now, we would reconstruct the 
archetypal ant as follows: 
Worker - — 
1. Mandibles narrow, short, curved, bidentate, closing tightly 
against clypeus. 
2. Maxillary palpi 6-segmented, labial palpi 4-segmented. 
3. Antennal scapes shorter than in most ants, but a little longer 
and more slender than in most tiphiids. 
4. Antennal funiculi long, slender, filiform, with 1 1 segments. 
5. Compound eyes large, convex, oval or round, situated near 
middle of sides of head. 
6. Ocelli well-developed. 
7. Promesonotal suture complete, movable. 
8. Mesonotum with scutum and scutellum separate and distinct. 
9. Mesonoto-metanotal suture complete, possibly movable. 
10. Metapleural gland bulla and meatus present. 
11. Tibial spurs 1, 2, 2. 
12. Tarsal claws toothed. 
13. Petiole consisting of a single segment, sessile in front, or 
nearly so, sessile and broadly joined to gaster behind (with 
little intervening constriction). 
14. Gaster unconstricted. 
15. Sting strong and functional. 
Of these character states, Sphecomyrma agrees with all but No. 13 
(petiole form) ; its status with regard to No. 2 (palpal segmenta- 
tion) is actually unknown, but we would strongly expect it to agree. 
The primitive Amblyopone species have workers agreeing with 
the archetype more or less closely in character Nos. 3, 7, 10, 11, 13 
and 15. Males of the larger and more primitive species of Amblyo- 
pone also agree in No. 1. 
The N othomyrmecia macrops worker agrees with Nos. 2, 4 (more 
or less), 5, 7, 10, 11, 12, 14 and 15. 
The Methocha stygia female agrees well to fairly well with all 
character states except 10 and 12. 
