The first specimens were collected in 1966, found embedded in amber which had been exposed in the cliffs of Cliffwood, New Jersey, by Edmund Frey and his wife.

In 1967, zoologists E. O. Wilson, Frank Carpenter and William L. Brown, Jr. published a paper describing and naming Sphecomyrma freyi.

The mandibles were short and wasp-like with only two teeth, the gaster was constricted, and the middle and hind legs had double tibial spurs.

It was suggested that ants diverged from tiphiid wasp ancestors, but later studies show that they originate from a different clade.

Further fossil evidence, along with its slender body and large compound eyes, suggest that they were epigaeic, foraging socially above ground and out in open areas.

[5] Only a single hymenopterous Upper Cretaceous fossil has been the subject of possible significance to the evolution of aculeate wasps and ants.

[6] However, there were several problems: as the fossil was only a single wing, scientists could not explain or answer whether or not the insect had key diagnostic body traits that would even place it within the subclade Aculeata.

[3] They found a large deep red piece of amber embedded in clay containing a number of insects, including some Diptera flies.

[B] Donald Baird of Princeton University first notified Carpenter about the recent discovery, and David Stager of the Newark Museum arranged to transfer the specimens to be studied and examined.

[11][12] The holotype was destroyed because the amber was accidentally cracked in half, separating the two workers from each other and later stored in a wooden cabinet in an uncovered drawer with other fossil insects for 30 years; the piece eventually deteriorated, appearing more dark and fractured.

Based on drawings, it was suggested that Mesozoic ants had long mandibles with multiple teeth, toothed tarsal claws and a broadly jointed petiole.

Examination of collected specimens, however, shows that these ants had very short mandibles, toothless tarsal claws and a separated petiole.

[3] S. freyi remained as the sole member of Sphecomyrma until a fossil closely resembling the species was collected in Canadian amber deposits in 1985.

[13] In 2005, new fossils of an undescribed Sphecomyrma ant and S. freyi were collected in the White Oaks outcrop in Sayreville, New Jersey.

[15][16] In 1987, Russian palaeoentomologist Gennady M. Dlussky elevated the subfamily at family level, renaming it as Sphecomyrmidae to accommodate Sphecomyrma and other fossil insects he studied throughout the Soviet Union.

[17] This placement was only short-lived as Wilson, with new morphological evidence, elevated the family back to subfamily level and all studied Cretaceous ants were put into Sphecomyrma or Cretomyrma.

As geniculate antennae allow brood and food manipulation, or even sociality, it is impossible to classify Sphecomyrma and relatives as ants.

[11][21] The evidence against Dlussky eventually reinstated Sphecomyrma and the subfamily as members of Formicidae in 1997,[11] although some sources published before 1997 did not formally recognise Sphecomyrminae at family level.

This was quickly dismissed due to overwhelming evidence supporting their placement within the Formicidae, and the fact the authors cited unpublished cladograms and disregarded the key diagnostic traits (synapomorphies) found in the ants.

[3] Currently, phylogenetic analyses recognise Sphecomyrma as a sister group to modern living ants, meaning that is a stem-group formicid.

The cuticle (outer exoskeleton of the body) is not sculptured and is covered with either scattered or spare setae, which are different types of bristle or hair-like structures.

The gland itself is covered in a whitish mass and is located in the anterodorsal region (meaning in front and toward the back) of the subcuticular chamber.

[14] Engel and Grimaldi coined the specific epithet after Bob Mesak, the original collector who donated the specimen to the museum.

The broad but shallow scrobes of the antennae, the size of the head and oval-shaped eyes can further distinguish S. mesaki from other Sphecomyrma ants.

The coxae, the proximal segment and functional base of the leg, are setose (bearing bristle or setae), inflated and large.

[11] The specimen numbered AMNH NJ-242 was collected from the White Oaks outcrop in 1995 and is currently preserved in the American Museum of Natural History.

The terminalia (the last segments of the abdomen) is difficult to examine due to a layer of froth covering the area, but there are two pairs of setose lobes.

[11] Further statements include that the morphology of sphecomyrmines would prevent workers from transporting larvae or engaging in trophallaxis (transfer of food between two nestmates) with them.

The presence of the metapleural gland also shows that Sphecomyrma was a eusocial (the highest level of organisation of animal sociality) insect and lived in colonies, as this gland possibly acts as a disinfectant in order to nest in soil and leaf litter without infecting the colony's nestmates and brood.

[11] The large eyes, long appendages and thin exoskeleton suggests that workers were epigaeic, where they foraged above ground and out in the open.