# List of informally named Mesozoic reptiles

Zoological names become available only when published according to the ICZN Code, which for a genus requires a description or diagnosis and the fixation of type material.<sup>[1](https://pmc.ncbi.nlm.nih.gov/articles/PMC2614166/)</sup><sup> • </sup><sup>[2](https://www.iczn.org/the-code/the-code-online/)</sup> A name that fails these requirements is a nomen nudum, Latin for "naked name": it is unavailable, but the same name may later be made available through a Code-compliant act of establishment.<sup>[3](https://www.amnh.org/content/download/136631/2239638/file/division-of-invertebrate-paleontology-%28microfossil-project%29-data-standards.pdf)</sup><sup> • </sup><sup>[7](https://code.iczn.org/glossary/)</sup> Other reasons a name may be rejected include being a nomen vanum, a nomen oblitum, a nomen dubium (based on undiagnostic, incomplete material), preoccupied, or misassigned.<sup>[1](https://pmc.ncbi.nlm.nih.gov/articles/PMC2614166/)</sup>

| Key fact | Detail |
|---|---|
| Common status of such names | Nomen nudum ("naked name"), a name not described according to the rules of the Code and therefore unavailable<sup>[1](https://pmc.ncbi.nlm.nih.gov/articles/PMC2614166/)</sup> |

## Why informal names exist

Several recurring situations produce informal names for Mesozoic reptiles:

- **Theses.** A name created in a dissertation is a nomen ex dissertationae and is not a formal publication.
- **Nicknames.** Descriptive nicknames circulate among researchers and in the press before any formal description.
- **Popular media.** Popular news articles on paleontology occasionally publish names ahead of their formal descriptions, and where a name simply has no published description it is attributed to the earliest user as a nomen nudum.<sup>[4](https://www.miketaylor.org.uk/tmp/Olshevsky_1991_A_revision_of_the_parainfraclass_Archosauria_Cope_1869_excluding_the_advanced_Crocodylia.pdf)</sup>

## Representative entries

The listed animals span several reptile lineages and parts of the world.

**Marine reptiles.** "Satsuma-mukashi-umigame" (サツマムカシウミガメ, "Satsuma ancient sea turtle", Satsuma being the old name of [Kagoshima](https://www.edgepedia.org/kagoshima)) is the nickname of a presumed chelonioidean sea turtle from the Cenomanian Goshoura Group of Shishijima Island, Kagoshima Prefecture, Japan.

## Context: Mesozoic reptile diversity

The Mesozoic hosted reptile groups well beyond dinosaurs. More than a dozen groups of marine reptiles are recognized from the Mesozoic fossil record, containing a minimum of 250 genera; the four major groups, Sauropterygia (including plesiosaurs), Ichthyopterygia, Mosasauridae, and Chelonioidea (sea turtles), each contain about 30 genera or more.<sup>[5](https://doi.org/10.1007/s12052-009-0139-y)</sup> Pterosaurs, the flying reptiles, dominated Mesozoic skies from the Triassic through the end of the [Cretaceous](https://www.edgepedia.org/cretaceous).<sup>[6](https://pteros.com/pterosaurs)</sup> Informal names arise in all of these groups whenever fragmentary or undescribed material attracts a nickname before a formal description is published.

## References

1. [Fossil quality and naming dinosaurs, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC2614166/)
2. [The Code Online, International Commission on Zoological Nomenclature](https://www.iczn.org/the-code/the-code-online/)
3. [AMNH Date Entry Dictionary, 2015 Edition](https://www.amnh.org/content/download/136631/2239638/file/division-of-invertebrate-paleontology-%28microfossil-project%29-data-standards.pdf)
4. [Olshevsky (1991), A Revision of the Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia](https://www.miketaylor.org.uk/tmp/Olshevsky_1991_A_revision_of_the_parainfraclass_Archosauria_Cope_1869_excluding_the_advanced_Crocodylia.pdf)
5. [Motani, R. (2009). The Evolution of Marine Reptiles. Evolution: Education and Outreach 2: 224–235](https://doi.org/10.1007/s12052-009-0139-y)
6. [Pterosaurs, Pteros](https://pteros.com/pterosaurs)
7. [Glossary, International Code of Zoological Nomenclature](https://code.iczn.org/glossary/)

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*Topic: Encyclopedia › Life and health › Animals › Vertebrates › Reptiles and amphibians › Reptiles › Reptile biology and paleobiology › Titles symbols to M*

*Initially written Sep 17, 2026 · Reviewed: Oct 21, 2026 · Edited: Oct 15, 2026; Oct 21, 2026; Oct 25, 2026 · Last review: Oct 21, 2026*

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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license