# Four mamenchisaurid evidence decisions

Scientific decision overlay for expanded-roster review; frozen PBDB records and historical screening checkpoints remain intact. This does not activate new live answers.

| Genus | Decision | Hidden-answer status |
| --- | --- | --- |
| Omeisaurus | Correct the type occurrence member only | pending broader approval |
| Xinjiangtitan | Preserve both Qiketai and Qigu; use secure geography | pending broader approval; geographic crowd resolved |
| Qijianglong | Keep Suining and the reported Upper Shaximiao alternative | hold: unresolved period |
| Zigongosaurus | Retain the accepted genus as a guess; hold the answer | hold: independent specimen identity and clue evidence |

All 484 previously supported full-roster pool targets were rechecked across 21656 reaching guesses. 9 comparisons initially exceed five; 0 supported targets remain blind above five after informative navigation.

## Decisions and release conditions

### Omeisaurus

The type-bearing bed is above Daanzhai limestone, rather than in that member. Clear Daanzhai for occurrence 474577; retain Shaximiao and the unresolved Lower/Upper correlations. All other referrals and occurrences remain separate.

Release condition: Complete normal Expert placement and clue approval; this metadata correction itself does not require a genus hold.

### Xinjiangtitan

The inspected literature provides competing assignments for the same SSV 12001 specimen. Neither is sufficiently decisive to eliminate the other. Broad Jurassic and Xinjiang/Shanshan geography are usable; fine age and exclusive formation clues are not.

Release condition: Use Turpan Basin, Xinjiang, China rather than disputed formation, and complete normal Expert placement and clue approval.

### Qijianglong

The original published assignment is Suining. The 2025 Upper Shaximiao reassignment cites unpublished surveys. Jurassic is a working interpretation, but regional Suining age research introduces a Cretaceous alternative. No direct published remap/date for the type quarry settles it. Treat period as unresolved in conservative comparisons.

Release condition: A specimen-specific horizon/date or an approved uncertainty-aware period clue. A single unqualified Jurassic profile is insufficient for release.

### Zigongosaurus

The original paper gives specimen 02501 and material from at least four individuals. The accepted PBDB genus coexists with a doubtful original species record. Omeisaurus fuxiensis has a separately based type; modern use of Zigongosaurus does not settle the older composite associations. Do not impose a synonym or transfer fossils.

Release condition: A specimen-based revision or catalog-supported diagnosis/referral establishing a coherent independent answer and usable clues.

## Xinjiangtitan: use basin as well as province

Xinjiang alone retains six: Bellusaurus, Hudiesaurus, Klamelisaurus, Rhomaleopakhus, Tienshanosaurus, Xinjiangtitan.

Turpan Basin, Xinjiang leaves at most 4 after every reaching guess. Known matches: Hudiesaurus, Rhomaleopakhus, Xinjiangtitan. Relevant unknowns retained: Tienshanosaurus.

Two Tienshanosaurus referrals lack reviewed basin metadata and stay possible. No county or basin is invented for them. Basin facts are attached only to exact occurrences or source-bound literature summaries.

## Comparisons initially above five

- Bisticeratops: initial maximum 6; terminal maximum 5; Kirtland Formation · US. Worst initial possibilities: Titanoceratops, Pentaceratops, Torosaurus, Navajoceratops, Terminocavus, Bisticeratops.
- Navajoceratops: initial maximum 6; terminal maximum 5; Kirtland Formation · US. Worst initial possibilities: Titanoceratops, Pentaceratops, Torosaurus, Navajoceratops, Terminocavus, Bisticeratops.
- Terminocavus: initial maximum 6; terminal maximum 5; Kirtland Formation · US. Worst initial possibilities: Titanoceratops, Pentaceratops, Torosaurus, Navajoceratops, Terminocavus, Bisticeratops.
- Yeneen: initial maximum 7; terminal maximum 5; Bajo de la Carpa Formation · AR. Worst initial possibilities: Traukutitan, Overosaurus, Inawentu, Yeneen, Bonitasaura, Neuquensaurus, Rinconsaurus.
- Daliansaurus: initial maximum 6; terminal maximum 5; Yixian Formation · CN. Worst initial possibilities: Daliansaurus, Jianianhualong, Liaoningvenator, Sinovenator, Mei, Sinusonasus.
- Sinusonasus: initial maximum 6; terminal maximum 5; Yixian Formation · CN. Worst initial possibilities: Daliansaurus, Jianianhualong, Liaoningvenator, Sinovenator, Mei, Sinusonasus.
- Wendiceratops: initial maximum 6; terminal maximum 5; Oldman Formation · CA. Worst initial possibilities: Spinops, Coronosaurus, Wendiceratops, Centrosaurus, Monoclonius, Avaceratops.
- Datousaurus: initial maximum 10; terminal maximum 5; Shaximiao Formation · CN. Worst initial possibilities: Daanosaurus, Dashanpusaurus, Qijianglong, Shunosaurus, Omeisaurus, Yuzhoulong, Datousaurus, Abrosaurus, Protognathosaurus, Zigongosaurus.
- Shunosaurus: initial maximum 10; terminal maximum 5; Shaximiao Formation · CN. Worst initial possibilities: Daanosaurus, Dashanpusaurus, Qijianglong, Shunosaurus, Omeisaurus, Yuzhoulong, Datousaurus, Abrosaurus, Protognathosaurus, Zigongosaurus.

## Limits

- These are comparisons of the selected guess roster, including genera held as answers. Candidate counts do not establish taxonomic or scientific approval.
- Existing parent relationships, inherited diets and other period profiles remain provisional. This review changes only the four declared cases.
- Qualified, non-primary and relevant unknown occurrences remain possible. Recorded nonmatches are not an exhaustive absence claim.
- Qijianglong is period-unresolved in candidate comparisons; this does not invent a confirmed Cretaceous occurrence. Its own working-Jurassic comparison is diagnostic only, while hidden-answer eligibility is held.
- The live sample remains 36 genera. The earlier locality screening reports remain reproducible historical checkpoints; this scientific overlay supersedes their four affected decisions.

Reproduce: `python review-mamenchisaurid-decisions.py`.