# Elfridia

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***Elfridia*** is a poorly known extinct [genus](/source/Genus) of [microsaur](/source/Microsaur) in the [family](/source/Family_(taxonomy)) [Gymnarthridae](/source/Gymnarthridae).

## History of study

*Elfridia* was named in 1985 by American paleontologist David Thayer based on material collected from [Carboniferous](/source/Carboniferous) exposures of the [Swisshelm Mountains](/source/Swisshelm_Mountains) in Arizona.[1] The genus name is derived from the nearby town of [Elfridia](/source/Elfrida,_Arizona), and the species name, *E. bulbidens,* is with respect to the bulbous teeth of the animal (*bulbi-* for 'bulbous' and *-dens* for 'tooth'). It is one of the oldest known 'microsaurs' and one of the few from the American southwest region.

## Anatomy

The holotype of *Elfridia* is a left mandible. Several other tooth-bearing fragments and isolated postcranial elements are assigned to this taxon. It is diagnosed by having lingually recurved tips of the teeth that are positioned asymmetrically on the labial portion. There are nine to ten teeth on the mandible with a greatly enlarged tooth along the mid-length of the tooth row.

## Relationships

Thayer placed *Elridia* within the [Gymnarthridae](/source/Gymnarthridae), but the fragmentary nature of the material has precluded its incorporation into a phylogenetic analysis to more thoroughly test and to evaluate its relationships with other 'microsaurs.' He compared it to both *[Euryodus](/source/Euryodus)* and *[Cardiocephalus](/source/Cardiocephalus)*, noting a mixture of features shared between the two gymnarthrids, such as the enlarged tooth (shared with *Euryodus primus*) and striations on the teeth (shared with *Cardiocephalus*).

## References

1. Thayer, David W. (1985). "New Pennsylvanian Lepospondyl Amphibians from the Swisshelm Mountains, Arizona". *Journal of Paleontology*. **59** (3): 684–700. [ISSN 0022-3360](https://www.worldcat.org/issn/0022-3360). [JSTOR 1304989](https://www.jstor.org/stable/1304989)

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Adapted from the Wikipedia article [Elfridia](https://en.wikipedia.org/wiki/Elfridia) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Elfridia?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.