A fossil-informed pattern of body size increase and local extinction in Basiceros dirt ants (Hymenoptera: Formicidae)

Basiceros dirt ants are morphologically distinct and widely distributed members of Neotropical communities. These ants possess features that aid in leaf litter camouflage and are larger than other closely related lineages with similar cryptic adaptations. Here, we report the first fossil of this genus-group, Basiceros enana sp. nov. from Miocene-aged Dominican amber, which reveals a pattern of body size evolution and disjunct biogeography. The fossil evidences the local extinction of Basiceros in the Caribbean, even as living Basiceros are known from Honduras to Southern Brazil. Using combined morphological and molecular datasets of all closely related lineages, we recover the evolutionary trajectory for body size within the group, demonstrating that body size was initially small in these ants and followed by a rapid expansion of body size in the common ancestor of all living species. Results reflect the capacity for early morphological evolution to influence perceived pa..., Our dataset is composed of data for 3 analyses: comparative morphospace, combined morphological-molecular phylogenetic reconstruction, and ancestral state reconstruction and body size evolutionary rates.
For the comparative morphospace, ant trait measurements were taken of all species within the genus Basiceros, as well as representatives from each genus within the Rhopalothrix genus group. Morphometric sampling included linear measurements of 19 morphological traits: 11 cephalic, three mesosomal, and five metasomal. We used a subset of measurements taken above for morphospace analysis to exclude measurements that cannot be obtained through photographs: HL1, HL2, HW1, MDL, SL1, SL2, PDL, AFL, FUL, EL, EW, ML, MFL, MTL, PTH, PTL, PTW, PPL, and PPW. We employed principal component analyses (PCA) on linear measurement data to reduce the dimensionality of the morphological dataset. All measurements can be found in the file Basiceros_enana_complete_database.xlsx.
For the ..., , # A fossil-informed pattern of body size increase and local extinction in Basiceros dirt ants (Hymenoptera: Formicidae)

[https://doi.org/10.5061/dryad.6q573n66p](https://doi.org/10.5061/dryad.6q573n66p)

## Description of the data and file structure

Complete morphometric database available in Dryad (10.5061/dryad.6q573n66p)

All supplemental figures and 3D semgnetations available in Zenodo ([https://doi.org/10.5281/zenodo.14748662)](https://doi.org/10.5281/zenodo.14748662)

R script available in Zenodo ([https://doi.org/10.5281/zenodo.14748666](https://doi.org/10.5281/zenodo.14748666))

### Files and variables on Dryad

**Phylogeny_divergence_dating.csv** - Summary of divergence dating results by parameter. 

**Basiceros_bodysize_evo_rate.csv** - Two separate tables outlining ancestral state reconstruction results used to reconstruct the body size shift through time. Table one demonstrates values representing PC1 (body size) change for each branch. Blank cells mean that the species do...