# Mesojassoides
**Mesojassoides** is a genus of extinct leafhopper ([Hemiptera](https://www.edgepedia.org/hemiptera): Cicadomorpha: Cicadellidae) known from the Late Cretaceous Fox Hills Formation of Colorado, dated to approximately 70 to 66 million years ago, in the [Maastrichtian](https://www.edgepedia.org/maastrichtian) stage.[1](https://zh.mindat.org/taxon-4773463.html) It contains a single species, **Mesojassoides gigantea**, described by P. W. Oman in 1937 from a fossil fore wing found in 1932.[2](https://zh.mindat.org/taxon-8499000.html)
| Key fact | Detail |
|---|---|
| Classification | Genus of fossil leafhoppers, family Cicadellidae, order Hemiptera[1](https://zh.mindat.org/taxon-4773463.html) |
| Age | 70.6 to 66.0 Ma, Late/Upper Cretaceous (Maastrichtian)[1](https://zh.mindat.org/taxon-4773463.html) |
| Type locality | Fox Hills Sandstone, Colorado, U.S.A.[3](https://www.sciencedirect.com/science/article/abs/pii/S0195667118303641) |
| Holotype | National Museum of Natural History #75521, 12 mm long, nearly complete, missing the clavus and a small section of the costal margin[2](https://zh.mindat.org/taxon-8499000.html) |
| Species | One accepted species, *Mesojassoides gigantea* Oman, 1937[1](https://zh.mindat.org/taxon-4773463.html) |
| Modern placement | Cicadellinae: Bathysmatophorini, based on tegminal venation (Szwedo, 2005)[3](https://www.sciencedirect.com/science/article/abs/pii/S0195667118303641) |
| Etymology | *Mesojassus* + *-oides* (similar to, from Greek *-ίδης*, son of)[4](https://iopn.library.illinois.edu/journals/inhs/article/download/837/782/3309) |
## Description and type specimen
The holotype, cataloged as [National Museum of Natural History](https://www.edgepedia.org/national-museum-of-natural-history) #75521, is 12 millimeters (0.47 in) long and nearly complete, missing the clavus and a small section of the costal margin.[2](https://zh.mindat.org/taxon-8499000.html) The genus was erected on the basis of fore-wing (tegmen) venation, the character set that has governed all subsequent assignments of the taxon.[3](https://www.sciencedirect.com/science/article/abs/pii/S0195667118303641)
The tegmen of *Mesojassoides* differs in venation from the superficially similar Eocene Baltic amber genus *Jantarivacanthus*: in *Mesojassoides* a wide appendix is present, vein RA is bifurcated with two ir veinlets, two r-m veinlets occur in the posterior portion, and veinlet m-cu 2 is straight rather than oblique.[5](https://www.researchgate.net/publication/235973925_Jantarivacanthus_kotejai_gen_et_sp_n_from_Eocene_Baltic_amber_with_notes_on_the_Bathysmatophorini_and_related_taxa_Hemiptera_Cicadomorpha_Cicadellidae)
## Taxonomic history
The genus was established by P. W. Oman in 1937 in his paper on fossil Hemiptera from the Fox Hills Sandstone of Colorado, published in the *Journal of Paleontology* (volume 11, page 38).[1](https://zh.mindat.org/taxon-4773463.html) Later authors treated the name repeatedly: J. W. Evans in 1956, K. G. A. Hamilton in 1992, Jacek Szwedo in 2005, and Chen and colleagues in 2018 all discussed or reclassified the genus.[1](https://zh.mindat.org/taxon-4773463.html)
**Changing family placement.** *Mesojassoides* was placed in the tribe Errhomenini by Oman and Musgrave in 1975 and by Nelson and Knight in 2000, and was believed to represent the ancestral stock of the Bathysmatophorini.[5](https://www.researchgate.net/publication/235973925_Jantarivacanthus_kotejai_gen_et_sp_n_from_Eocene_Baltic_amber_with_notes_on_the_Bathysmatophorini_and_related_taxa_Hemiptera_Cicadomorpha_Cicadellidae) In 2005, Szwedo assigned *Mesojassoides gigantea* to Cicadellinae: Bathysmatophorini on the basis of tegminal venation patterns.[3](https://www.sciencedirect.com/science/article/abs/pii/S0195667118303641) A Russian review of Mesozoic and Cenozoic homopterans likewise listed *Mesojassoides* Oman among the [Cretaceous](https://www.edgepedia.org/cretaceous) cicadellid genera of North America, alongside *Jascopus*.[6](https://www.paleoentomology.ru/publ/books/mz-kz-1980.pdf)
## Geological setting
The Fox Hills Sandstone, the unit that yielded the type specimen, is a [Late Cretaceous](https://www.edgepedia.org/late-cretaceous) formation of the Montana group, representing the final marine deposits of the [Western Interior Seaway](https://www.edgepedia.org/western-interior-seaway); it outcrops in Colorado, Wyoming, Montana, and the Dakotas.[7](https://ngmdb.usgs.gov/Geolex/UnitRefs/FoxHillsRefs_8187.html) The insect fossils come from the uppermost Cretaceous interval, with the genus recorded at 70.6 to 66.0 Ma.[1](https://zh.mindat.org/taxon-4773463.html) The West Fork San Arroyo Creek locality in Colorado, a Fox Hills site cataloged in the Paleobiology Database, lists *Mesojassoides gigantea* among its documented finds, together with Coreidae, marine mollusks, and fossil wood fragments.[8](https://rockhounding.org/us/co/west-fork-san-arroyo-creek-co)
## Significance
Fossil leafhoppers are poorly documented: fewer than 100 confirmed fossil cicadellid species had been erected as of 2018, with most from the Cenozoic, and only a handful recorded from the Cretaceous.[3](https://www.sciencedirect.com/science/article/abs/pii/S0195667118303641) *Mesojassoides* is one of the few named Cretaceous cicadellid genera, and its Maastrichtian age makes it a late-surviving representative of early leafhopper lineages just before the end-Cretaceous boundary.[3](https://www.sciencedirect.com/science/article/abs/pii/S0195667118303641) • [1](https://zh.mindat.org/taxon-4773463.html)
## References
1. [Mesojassoides, Mindat fossil taxon record (data courtesy of PBDB, GBIF, EOL)](https://zh.mindat.org/taxon-4773463.html)
2. [Mesojassoides gigantea, Mindat fossil taxon record](https://zh.mindat.org/taxon-8499000.html)
3. [Chen J., Wang B. et al. (2018). A representative of the modern leafhopper subfamily Ledrinae in mid-Cretaceous Burmese amber (Hemiptera, Cicadellidae). Cretaceous Research 95, 252–259.](https://www.sciencedirect.com/science/article/abs/pii/S0195667118303641)
4. [Dmitriev, D. A. Etymology and grammatical gender of generic names in Auchenorrhyncha (Hemiptera). Illinois Natural History Survey Bulletin 43.](https://iopn.library.illinois.edu/journals/inhs/article/download/837/782/3309)
5. [Szwedo, J. (2005). Jantarivacanthus kotejai gen. et sp. n. from Eocene Baltic amber, with notes on the Bathysmatophorini and related taxa (Hemiptera: Cicadomorpha: Cicadellidae). Polskie Pismo Entomologiczne 74, 251–276.](https://www.researchgate.net/publication/235973925_Jantarivacanthus_kotejai_gen_et_sp_n_from_Eocene_Baltic_amber_with_notes_on_the_Bathysmatophorini_and_related_taxa_Hemiptera_Cicadomorpha_Cicadellidae)
6. [Mesozoic and Cenozoic insects (Auchenorrhyncha section), Paleoentomology.ru](https://www.paleoentomology.ru/publ/books/mz-kz-1980.pdf)
7. [Geolex: Fox Hills publications, USGS National Geologic Map Database](https://ngmdb.usgs.gov/Geolex/UnitRefs/FoxHillsRefs_8187.html)
8. [West Fork San Arroyo Creek, Colorado: Rockhounding Site](https://rockhounding.org/us/co/west-fork-san-arroyo-creek-co)
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*Topic: Encyclopedia › Life and health › Animals › Invertebrates › Arthropods › Insects › True bugs and allies › Fossil Hemiptera*
*Initially written Sep 17, 2026 · Reviewed: Oct 21, 2026 · Edited: Oct 11, 2026; Oct 15, 2026; Oct 21, 2026 · Last review: Oct 21, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license