Eophis

Eophis Temporal range: Middle Jurassic, Bathonian PreꞒ Ꞓ O S D C P T J K Pg N ↓
Syntype dentary fragments of Eophis
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Family:	†Parviraptoridae
Genus:	†Eophis Caldwell et al. 2015
Type species
Eophis underwoodi Caldwell et al. 2015

Eophis (lit. 'dawn snake') is a potentially dubious genus of reptiles in the enigmatic clade Parviraptoridae, known from the Middle Jurassic (Bathonian) Forest Marble Formation of the United Kingdom. The genus containing a single species, Eophis underwoodi, known from three dentary fragments and a maxilla fragment from Kirtlington Quarry.^[1]

Initial interpretations proposed anguimorph lizard affinities, but it was reintepreted as a stem snake by Caldwell et al. (2015),^[1] a placement re-affirmed in a subsequent 2017 analysis.^[2] In 2025, Benson and colleagues described a new parviraptorid, Breugnathair, known from much more complete remains. While these authors did not rule out snake affinities for parviraptorids, they proposed other possible placements for the clade, including as stem squamates (in which case they would have convergently evolved their snake-like anatomy) or as early toxicoferans outside of Ophidia. These authors were unable to identify distinct traits in the Eophis fossil material, noting that observable differences could be due to immaturity or small size. As such, they regarded it as a nomen dubium and an indeterminate parviraptorid.^[3]

Phylogeny

Cladogram based in the phylogenetic analysis by Caldwell et al. (2015):^[1]

Ophidia	Portugalophis Parviraptor Eophis Unnamed sp. Diablophis Dinilysia Madtsoiidae Najash Coniophis Serpentes (Modern snakes)

References

1. Caldwell, M. W.; Nydam, R. L.; Palci, A.; Apesteguía, S. N. (2015). "The oldest known snakes from the Middle Jurassic-Lower Cretaceous provide insights on snake evolution". Nature Communications. 6: 5996. Bibcode:2015NatCo...6.5996C. doi:10.1038/ncomms6996. hdl:11336/37995. PMID 25625704.
2. Harrington, Sean M.; Reeder, Tod W. (2017-02-18). "Phylogenetic inference and divergence dating of snakes using molecules, morphology and fossils: new insights into convergent evolution of feeding morphology and limb reduction". Biological Journal of the Linnean Society. 121 (2): 379–394. doi:10.1093/biolinnean/blw039. ISSN 0024-4066.
3. Benson, Roger B. J.; Walsh, Stig A.; Griffiths, Elizabeth F.; Kulik, Zoe T.; Botha, Jennifer; Fernandez, Vincent; Head, Jason J.; Evans, Susan E. (October 1, 2025). "Mosaic anatomy in an early fossil squamate". Nature. doi:10.1038/s41586-025-09566-y. ISSN 0028-0836.