Size reference
Source supported6.62 mm fossil body reference
G. gracilis2014 holotype JZC Bu324A; not CASENT0741232’s measured length or a genus-wide range. [D2]
EXHIBIT 225
Gerontoformica
Gerontoformica
Prehistoric insect
Gerontoformica was a stem ant preserved in Cretaceous amber, with fossil evidence informing early cooperation. [1]
TWO WAYS TO PICTURE THE PAST
Science & the silver screen
Compare the evidence with the familiar movie image. The illustrations are not to a shared scale.
01 / SOURCE-INFORMED RECONSTRUCTION
A life reconstruction from the evidence
Image unavailableIllustrative life reconstruction of Gerontoformica in a period-appropriate environment; coloration and missing anatomy are interpretations.The exhibit and its credited image source remain available.
An illustrative reconstruction. Compare its anatomy with the evidence and limitations in the dossier. [2]
Source-informed reconstruction. Appearance evidence [2]. Original illustration; missing anatomy, coloration and scenery include interpretation.
Fossils constrain this life reconstruction. Missing anatomy, coloration and the environmental scene include interpretation; the dossier explains the evidence limits.
02 / MOVIE-STYLE INTERPRETATION
A cinematic imagination
Image unavailableIllustrative living reconstruction of Gerontoformica; missing anatomy and exact colors remain uncertain.The exhibit and its credited image source remain available.
An illustrative reconstruction. Compare its anatomy with the evidence and limitations in the dossier. Lighting, coloration and scenery are artistic choices. This image does not document a fossil locality or behavior.
Original artwork · artistic interpretation.
Scientific view: source-informed reconstruction, credited paleoart or specimen-based imagery. Movie-style view: Original artistic interpretation. Reconstructions involve uncertainty.
PERIODLate Cretaceous (Cenomanian)[1]
DIETPredation inferredEvidence and uncertainty in the dossier
TOTAL LENGTHSee the dossierEstimate scope matters
FOSSILS FOUNDMyanmar, France[1]
MEET THE ANIMAL
Meet Gerontoformica
Gerontoformica was an early ant genus known from Cretaceous amber in Myanmar and France. Its slender adults had six legs and a narrow waist. A2014 specimen of the species Gerontoformica gracilis was described as6.62 millimeters long. The paper used an older genus name, Sphecomyrmodes, so reading the later revision is necessary to connect the same species rather than count it twice. [D2]
One remarkable amber piece preserves an adult close to a pupa, an immature stage before an ant becomes an adult. Scans helped researchers identify both as Gerontoformica gracilis. Because a pupa cannot walk and the resin contained little loose debris, they proposed that an adult was transporting it. That interpretation supports cooperative brood care, while the fossil is still a snapshot rather than a film of the action. [D1]
More recent research adds different evidence. A2025 amber sample contains a queen-form Gerontoformica gracilis with three workers, helping compare female castes. The same study describes a male of another species, Gerontoformica priapos. Those discoveries strengthen the picture of early ant society, but they do not establish the size of a whole colony, its nest location or the details of mating behavior. [D4]
PREHISTORIC ANIMAL DOSSIER
A life in profile.
The animal, the evidence, and the questions still open.
Head scans supply anatomical feeding clues; complete diet and particular prey are not preserved. [D3]
Profile scope: Genus — Gerontoformica; gallery anchored to wingless adult female G. gracilis CASENT0741232 from Kachin amber, Myanmar. [D1]
- Time
- Late Cretaceous (Cenomanian)
- Fossil locations in this exhibit
- Myanmar, France
How to read the evidence
Source supported identifies a description documented by the cited source. Inferred marks a reconstruction or functional estimate. Debated marks competing interpretations. Not established means the sources reviewed for this dossier do not support a firm conclusion; it does not mean a behavior never occurred.
A size reference is an estimate, not a population range. Nesting evidence does not by itself establish courtship, mate choice, or lifelong pairing.
Body mass
Not establishedNot established here
The inspected measured description gives no fossil-individual body-mass estimate. [D2]
Diet
InferredPredatory feeding inferred
Comparative head muscles and mouthparts suggest above-ground predation; complete diet and prey remain unidentified. [D3]
Habitat
InferredAmber-forest surroundings inferred
French and Myanmar amber occurrences identify preservation settings; the focal specimen’s exact living microhabitat is unknown. [D1]
Movement
InferredWingless adult walking inferred
The focal female has six articulated legs; its speed is unmeasured, and other genus members have wings. [D2]
Distinctive anatomy
Source supportedSlender body; one petiole
G. gracilis has long legs, bidentate jaws and short basal antennal segments; it lacks Haidomyrmex’s upcurved blades. [D2]
Reproduction & life together
Reproduction
Source supportedPupa and adult stages documented
CT comparison links a wingless pupa with a nearby G. gracilis adult; eggs and an oviposition site are not described. [D1]
Courtship
Not establishedNot established here
A2025 G. priapos male shows sexual morphology, not mating behavior or a G. gracilis mating partner. [D4]
Social behavior
InferredCooperative brood care inferred
The adult–pupa association supports proposed brood transport; a 2025 queen–worker association provides additional caste evidence. [D1] [D4]
Dossier research & sources
Sources and inspection notes for the claims in this profile.
- Evidence for the evolution of eusociality in stem ants and a systematic revision of†Gerontoformica (Hymenoptera: Formicidae)Zoological Journal of the Linnean Society; Boudinot et al., 2022 · Accessed 2026-10-06Original institutional OIST PDF inspected: revised genus diagnosis, Sphecomyrmodes synonym, Myanmyrma transfer limits and G. cretacica nomen dubium; CT-linked adult/pupa G. gracilis with transport interpreted from immobility and clean matrix. · Inspected: page
- A Diverse Ant Fauna from the Mid-Cretaceous of Myanmar (Hymenoptera: Formicidae)PLOS ONE; Barden & Grimaldi, 2014 · Accessed 2026-10-06Original full article/PDF inspected, especially Sphecomyrmodes gracilis description and holotypeJZC Bu324A6.62 mm. This historical combination is joined to the later genus revision; it is not a second exhibit. · Inspected: page
- The First Reconstruction of the Head Anatomy of a Cretaceous Insect,†Gerontoformica gracilis (Hymenoptera: Formicidae), and the Early Evolution of AntsInsect Systematics and Diversity; Richter et al., 2022 · Accessed 2026-10-06Original OIST full PDF captured. CASENT0741232 identification, head-anatomy Results and functional Discussion inspected: generalized above-ground predation is a comparative inference, not observed feeding. · Inspected: page
- Systematics and early evolution of ants (Hymenoptera: Formicidae): the first male and worker-queen association for†GerontoformicaMyrmecological News; Zhuang et al., 2025 · Accessed 2026-10-06Original full publisher PDF captured; abstract, G. gracilis LYU-BM2005 material (dealate queen with three workers), G. priapos male and association discussion inspected. Male identity does not show a mating scene or identify a G. gracilis male. · Inspected: page
- Sensory evidence for complex communication and advanced sociality in early antsScience Advances; Taniguchi et al., 2024 · Accessed 2026-10-06Original full EuropePMC body captured; G. gracilis antennal study and discussion inspected. Sensilla basiconica/multiporesetal comparisons support chemosensory communication inference, not preserved conversations or pheromone chemistry. · Inspected: page
THE STORY IN THE FOSSILS
Different windows into an early ant
Antenna microstructures provide another kind of evidence: comparison with modern ants suggests chemical recognition. That inference complements fossil associations without preserving an actual social exchange. [5]
A note on scale and time
The dossier identifies the scope of each reference estimate. A mount, an individual fossil and a species-wide adult range are different measurements. Comparison metrics remain unavailable where adult scope has not been established. Unknown does not mean zero.
Sources & editorial notes
Sources support the stated claims and scopes. Refer to the evidence notes for uncertainty.
- Evidence for the evolution of eusociality in stem ants and a systematic revision of†Gerontoformica (Hymenoptera: Formicidae)Zoological Journal of the Linnean Society; Boudinot et al., 2022 · Accessed 2026-10-06Original institutional OIST PDF inspected: revised genus diagnosis, Sphecomyrmodes synonym, Myanmyrma transfer limits and G. cretacica nomen dubium; CT-linked adult/pupa G. gracilis with transport interpreted from immobility and clean matrix. · Inspected: page
- A Diverse Ant Fauna from the Mid-Cretaceous of Myanmar (Hymenoptera: Formicidae)PLOS ONE; Barden & Grimaldi, 2014 · Accessed 2026-10-06Original full article/PDF inspected, especially Sphecomyrmodes gracilis description and holotypeJZC Bu324A6.62 mm. This historical combination is joined to the later genus revision; it is not a second exhibit. · Inspected: page
- The First Reconstruction of the Head Anatomy of a Cretaceous Insect,†Gerontoformica gracilis (Hymenoptera: Formicidae), and the Early Evolution of AntsInsect Systematics and Diversity; Richter et al., 2022 · Accessed 2026-10-06Original OIST full PDF captured. CASENT0741232 identification, head-anatomy Results and functional Discussion inspected: generalized above-ground predation is a comparative inference, not observed feeding. · Inspected: page
- Systematics and early evolution of ants (Hymenoptera: Formicidae): the first male and worker-queen association for†GerontoformicaMyrmecological News; Zhuang et al., 2025 · Accessed 2026-10-06Original full publisher PDF captured; abstract, G. gracilis LYU-BM2005 material (dealate queen with three workers), G. priapos male and association discussion inspected. Male identity does not show a mating scene or identify a G. gracilis male. · Inspected: page
- Sensory evidence for complex communication and advanced sociality in early antsScience Advances; Taniguchi et al., 2024 · Accessed 2026-10-06Original full EuropePMC body captured; G. gracilis antennal study and discussion inspected. Sensilla basiconica/multiporesetal comparisons support chemosensory communication inference, not preserved conversations or pheromone chemistry. · Inspected: page
KEEP EXPLORING
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