MicroCT scan image data of tiger beetle (Palaeoiresina cassolai) Eocene Baltic amber fossils

The fossil record suggests some insect species have a marked longevity.
The oldest fossils purported to represent extant insect species are from
the Oligocene and Eocene. One of the most cited is the extant tiger beetle
Tetracha carolina (Coleoptera: Cicindelidae). This fossil beetle was
identified over a century ago by Walther Horn in Eocene Baltic amber. We
examined this and compared it to the previously described cincindelid
Baltic amber fossil Palaeoiresina cassolai using X-ray microscopy and 3D
imaging techniques. We conclude that Horn’s tiger beetle is conspecific
with the Eocene P. cassolai and is a member of an extinct stem group
lineage of Cicindelidae. Based on a review of all the tiger beetle fossils
described from Cretaceous and Paleogene deposits, we found that the
assignment of these fossil species to extant lineages is not supported.
There is currently no synapomorphic fossil evidence for Cretaceous
Manticorni or Megacephalini nor is there evidence for Eocene Iresina. We
provide evidence that rejects the idea of a recent beetle species
persisting since the Eocene period, which is crucial for using the
currently known fossil Cicindelidae species to calibrate divergence dating
of beetle phylogenies.