Seldsienean
extinct genus of machimosaurid
Seldsienean is an extinct genus of teleosauroid thalattosuchian from the Middle Jurassic of England and France. The only known species, S. megistorhynchus, is known from remains from the Calcaire de Caen and the Cornbrash Formation. In life, Seldsienean was a marine reptile that would have fed mostly on fish and other small animals.
Taxonomy
The type species, S. megistorhynchus, was originally named as a species Steneosaurus in 1866. The genus Steneosaurus was used as a longtime wastebasket taxon for various teleosauroid specimens and had more than a dozen species. The type species, Steneosaurus rostromajor is undiagnostic, making the genus and species dubious and invalid. Additionally, many species of so-called "Steneosaurus" were found to be quite different and unrelated to one another, thus needing new generic names.
In 2020, Michela Johnson and colleagues reassigned "Steneosaurus" megistorhynchus to the new genus Seldsienean, resulting in the new combination Seldsienean megistorhynchus. The generic name is derived from Old English and translates to "seldom seen one" in reference to its fossils being rarer compared to other Bathonian teleosauroids.
Classification
Seldsienean was initially recovered as a basal member of Machimosauridae, a family of large-bodied, marine-adapted reptiles.
This brief starts where responsible research should: with the source description of “Seldsienean” as extinct genus of machimosaurid. Everything that follows is an evidence route, not borrowed authority.
Why this record matters
The subject matters to the science & nature register because the source frames it as extinct genus of machimosaurid. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Stable identifiers, scientific names and standards terminology offer the best bridge between this overview and specialist evidence. The source revision retrieved here is dated Aug 31, 2026. The linked authority identifier is Q90690021. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1866 and 2020.
Current terminology should not be projected backward without checking the classification used when the underlying evidence was created. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Check terminology, classification and the date of the cited evidence. Scientific names and technical consensus can change while older records retain historical value.
- Current terminology
- Classification context
- Finding cited technical literature
Primary datasets, specimen catalogues, standards bodies and the most recent peer-reviewed literature.
Three-step research path
- Establish the record: confirm the title “Seldsienean”, its source revision and the description used here.
- Expand the search: follow Seldsienean primary sources, Seldsienean archive and Seldsienean research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Seldsienean”?
- Is the terminology current, historical or disputed?
- Which observation, specimen, dataset or publication supports the account?
Search terms from this dossier
This entry incorporates text from “Seldsienean” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.