Claim

The 518-million-year-old fossil Yujingia glutenotunica is phylogenetically placed within a grade of tentaculate fossils immediately basal to the last common ancestor of modern ambulacrarians.

Type COMPARATIVE · truth-evaluable: yes · status at snapshot: ACTIVE · created seq 18590 · qualifiers {"population":"Yujingia glutenotunica from the early Cambrian Chengjiang biota; comparison with modern ambulacrarians and fossil tentaculate forms."}

Referenced 93 times: checked 2, looked up by assistants 2, viewed 60, shared 29. A count of attention, not evidence.

Topics

Biology · 1efd24fe Ancient · 1efd24fe

Assessment

Supported

Score: 0.9381 under ledger-default@0.3.0 at snapshot 27745

3 of 4 review checks done · 1 counted · 2 by the author only

2 independent evidence lineages · review checks 1 of 4 · stability MEDIUM

Main unresolved issue: 3 counted evidence items have no independence review; repeats of one origin may be counted as several coverage:0ec45e87-bf07-8f6d-967b-8561ce52ab7c

Not yet independently audited.Evidence reviewed so far supports this claim, but only 1 of 4 review checks has been done.A quoted passage from phys.org was not found on the page when Galedra fetched it.

Why?

Strongest counted support: The packet directly states that Yujingia is placed within a grade of tentaculate fossils immediately basal to modern ambulacrarians' last common ancestor. weight 1.800000 evidence

Suppressed as dependent: The abstract places Yujingia immediately basal to the last common ancestor of modern ambulacrarians.

Review gaps: qualifiers reviewed, opposing search done, independence reviewed

What would most change this: One independent, direct measurement that contradicts this claim would move it from Supported to Leans supported.

Hide calculation

0.9381 under ledger-default@0.3.0 at snapshot 27745 · state Supported · Review checks: 1 of 4 · stability MEDIUM · 3 sources, 2 independent lineages

Model ledger-default@0.3.0 (the default model, not the answer) · snapshot 27745 · trace sha256:1028988bf86dd3736ed55c8e0314f4d052551f128d1588926a16c8d35c654aa6

Last changed at entry seq 24935; nothing logged since has borne on this claim.

How the number was reached

Each counted link is weighed by multiplying the factors the model declares; a factor it does not declare is not shown. Every factor name below links to what that number means.

Link	Working	Weight	Counted as
ea07fc44 support	relevance DIRECT 2.0 × observation EXPERT_ANALYSIS 0.3 × interpretation 0 steps, 1 − 0.15 × 0 1.000000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	0.600000	0.000000 (dependent strongest only, kept 2a5ca8e4)
d0112421 support	relevance STRONG 1.2 × observation DIRECT_TEXT 0.9 × interpretation 1 step, 1 − 0.15 × 1 0.850000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	0.918000	0.918000
2a5ca8e4 support	relevance DIRECT 2.0 × observation DIRECT_TEXT 0.9 × interpretation 0 steps, 1 − 0.15 × 0 1.000000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	1.800000	1.800000

prior 0.50 → log-odds 0.000000 + 2.718000 (the counted weights) = 2.718000 → probability 0.9381

Under neighbouring settings of the same model: 0.8702 to 0.9716, a spread of 0.1014.

Half-even rounding, six places for weights and four for the probability. The same inputs under the same model reproduce this exactly; that is what the trace hash above is for. How a score is worked out explains every factor, why it is there, and what the model sets it to.

Your view

Registered views

Nobody has registered a view yet.

Registered views are personal belief, not evidence: they never change Galedra's assessment. Affiliations are self-declared and shown only for groups of 5 or more.

Checked as part of

Statements this claim was broken out of. The claim is scored on its own; a statement's reading only counts its claims.

“The 518-million-year-old fossil Yujingia glutenotunica is phylogenetically placed within a grade of tentaculate fossils immediately basal to the last common...” · 1 claim · 29 September 2026
“The 518-million-year-old fossil Yujingia glutenotunica preserves pinnate filter-feeding appendages and is phylogenetically placed near the last common...” · 2 claims · 29 September 2026

Evidence for

The abstract places Yujingia immediately basal to the last common ancestor of modern ambulacrarians.

From Cambrian fossils illuminate the ambulacrarian common ancestor Read 2026-09-29 Relevance DIRECT Steps 0 Counted
The secondary report places Yujingia close to the last common ancestor of living ambulacrarians and describes it as a transitional fossil based on anatomical and phylogenetic analysis.

From Half-billion-year-old fossils rewrite the origin story of starfish Read 2026-09-29 Relevance STRONG Steps 1 Counted

Independent secondary report of the same fossil study; not an independent fossil dataset.
The packet directly states that Yujingia is placed within a grade of tentaculate fossils immediately basal to modern ambulacrarians' last common ancestor.

From Cambrian fossils illuminate the ambulacrarian common ancestor Read 2026-09-29 Relevance DIRECT Steps 0 Counted

Evidence against

None.

Qualifications

None.

Suppressed as dependent

Evidence	Group	Kept instead
47be0f1d		2a5ca8e4

Inferences

Concluded from

None.

Used as a premise in

None.

An inference is interpretation, not evidence: it never changes the assessment of its conclusion. Each premise is a claim with its own evidence.

Threads

None. Threads are for disagreements about how a determination was made — a statement whose figures are not in the passage it rests on, two sources that may share an origin. Something about the world belongs in the evidence above.

Claim edges

None. Edges are stored and displayed; v0.1 does not propagate probability across them.

Review checklist

Review checks: 1 of 4

3 checks by this claim's own author, alongside the independent review above. 1 OPPOSING EVIDENCE SEARCH · 1 QUALIFIER CHECK · 1 EVIDENCE VERIFICATION. A check by the person who recorded a claim does not raise its review coverage.

Check	Done	By
qualifiers reviewed	no
opposing search done	no
independence reviewed	no
primary source reviewed	yes	ea07fc44, 2a5ca8e4

Summary

Supported. The main support is: The secondary report places Yujingia close to the last common ancestor of living ambulacrarians and describes it as a transitional fossil based on anatomical and phylogenetic analysis. ef54add5

1 further item repeats the same origin and is not independent evidence. 47be0f1d

A search for evidence in the opposing direction found none. b2b11b2b

Review checks: 1 of 4. coverage:0ec45e87-bf07-8f6d-967b-8561ce52ab7c

Generated by stub-v0.1; every sentence cites graph ids.

Contribution history

seq	event	detail
18590	APPENDED
18591	ACCEPT	AUTOMATIC_AFTER_VALIDATION
18602	LINK_EVIDENCE	by 1efd24fe (accepted)
18612	LINK_EVIDENCE	by 1efd24fe (accepted)
22080	TASK_RESULT	by 1efd24fe (accepted)

Score trace

{
  "claim": "0ec45e87-bf07-8f6d-967b-8561ce52ab7c",
  "links": [
    {
      "kept": "f4e8b529-d6dd-89b2-8225-b3652a5ca8e4",
      "link": "475bd406-9bd2-852a-92ff-2bebea07fc44",
      "group": null,
      "reason": "dependent_strongest_only",
      "edition": "NAMED_OR_UNRELATED",
      "evidence": "8b8cc279-665c-8130-82e7-240247be0f1d",
      "direction": "SUPPORT",
      "magnitude": "0.600000",
      "relevance": "DIRECT",
      "extraction": "UNVERIFIED",
      "provenance": "INDEPENDENT",
      "observation": "EXPERT_ANALYSIS",
      "source_type": "PRIMARY_TEXT",
      "authenticity": "UNVERIFIED",
      "audit_confirmed": false,
      "effective_weight": "0.000000",
      "interpretive_steps": 0
    },
    {
      "link": "ebad57d9-9eda-83a3-9548-22a8d0112421",
      "group": null,
      "edition": "NAMED_OR_UNRELATED",
      "evidence": "d8158bca-aba2-83ed-aca9-6c42ef54add5",
      "direction": "SUPPORT",
      "magnitude": "0.918000",
      "relevance": "STRONG",
      "extraction": "UNVERIFIED",
      "provenance": "INDEPENDENT",
      "observation": "DIRECT_TEXT",
      "source_type": "SECONDARY_TEXT",
      "authenticity": "UNVERIFIED",
      "audit_confirmed": false,
      "effective_weight": "0.918000",
      "interpretive_steps": 1
    },
    {
      "link": "f4e8b529-d6dd-89b2-8225-b3652a5ca8e4",
      "group": null,
      "edition": "NAMED_OR_UNRELATED",
      "evidence": "09be090f-1d7c-80eb-9fbd-04a039b0eaf3",
      "direction": "SUPPORT",
      "magnitude": "1.800000",
      "relevance": "DIRECT",
      "extraction": "UNVERIFIED",
      "provenance": "INDEPENDENT",
      "observation": "DIRECT_TEXT",
      "source_type": "PRIMARY_TEXT",
      "authenticity": "UNVERIFIED",
      "audit_confirmed": false,
      "effective_weight": "1.800000",
      "interpretive_steps": 0
    }
  ],
  "model": "ledger-default@0.3.0",
  "prior": "0.50",
  "variants": {
    "spread": "0.1014",
    "permissive": "0.9716",
    "conservative": "0.8702"
  },
  "code_hash": "sha256:c61a6fdf35a754a0d7e958df149036a083c0eaeb7d2d2e52704ec32b0c36def7",
  "contested": false,
  "stability": "MEDIUM",
  "claim_type": "COMPARATIVE",
  "config_hash": "sha256:86768038080b8ab5233f1e4b7aba10af05b5bb44caa432095150b90e81209809",
  "probability": "0.9381",
  "provisional": true,
  "evidence_sum": "2.718000",
  "snapshot_seq": 24935,
  "prior_log_odds": "0.000000",
  "support_groups": 2,
  "model_dependent": false,
  "review_coverage": "0.25",
  "truth_evaluable": true,
  "assessment_state": "SUPPORTED",
  "review_checklist": {
    "qualifiers_reviewed": {
      "by": [],
      "ok": false
    },
    "opposing_search_done": {
      "by": [],
      "ok": false
    },
    "independence_reviewed": {
      "by": [],
      "ok": false
    },
    "primary_source_reviewed": {
      "by": [
        "475bd406-9bd2-852a-92ff-2bebea07fc44",
        "f4e8b529-d6dd-89b2-8225-b3652a5ca8e4"
      ],
      "ok": true
    }
  },
  "contradict_groups": 0,
  "rounding_boundary": false,
  "posterior_log_odds": "2.718000",
  "not_applicable_reason": null,
  "independence_unreviewed": 3
}