Claim

Dongoconodon platycauda, an approximately 125-million-year-old Early Cretaceous mammal from China, is the earliest confirmed swimming mammal discovered to date.

Type HISTORICAL · truth-evaluable: yes · status at snapshot: ACTIVE · created seq 23936

a comma-separated series may list several propositions

Referenced 186 times: checked 2, looked up by assistants 0, viewed 118, shared 66. A count of attention, not evidence.

Topics

Biology · 1efd24fe Archaeology · 1efd24fe

Assessment

Supported

Score: 0.8581 under ledger-default@0.3.0 at snapshot 27745

2 of 4 review checks done · 0 counted · 2 by the author only

3 independent evidence lineages · review checks 0 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:3a2ab0f3-4770-8835-9a65-fb44f398dfca

Not yet independently audited.Evidence points both ways.Evidence reviewed so far supports this claim, but only 0 of 4 review checks have been done.A quoted passage from feng.ifeng.com was not found on the page when Galedra fetched it.

Why?

Strongest counted support: Global Times reports that the approximately 125-million-year-old fossil is the earliest confirmed swimming mammal discovered to date. weight 1.800000 evidence

Strongest counted contradiction: An earlier Jurassic mammaliaform was reported as the earliest-known swimming mammal, so Dongoconodon is not earliest under an unqualified mammal definition. weight 1.800000 evidence

Suppressed as dependent: Global Times reports that the approximately 125-million-year-old fossil is the earliest confirmed swimming mammal discovered to date.

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

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

Hide calculation

0.8581 under ledger-default@0.3.0 at snapshot 27745 · state Supported · Review checks: 0 of 4 · stability MEDIUM · 4 sources, 3 independent lineages

Model ledger-default@0.3.0 (the default model, not the answer) · snapshot 27745 · trace sha256:86d4e539ea87d4ce6a75e81432ca801e1dba80ebad93f52215a6b2c0bc95375e

Last changed at entry seq 25936; 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
b071d1c0 support	relevance DIRECT 2.0 × observation ARCHAEOLOGICAL 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	0.000000 (dependent strongest only, kept 3a1ba9fb)
54d883a3 contradict	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
3a1ba9fb support	relevance DIRECT 2.0 × observation ARCHAEOLOGICAL 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
186f0acb 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 + 1.800000 (the counted weights) = 1.800000 → probability 0.8581

Under neighbouring settings of the same model: 0.7790 to 0.9121, a spread of 0.1331.

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.

“Dongoconodon platycauda, an approximately 125-million-year-old Early Cretaceous mammal from China, is the earliest confirmed swimming mammal discovered to date.” · 1 claim · 29 September 2026
“Dongoconodon platycauda is an approximately 125-million-year-old early mammal with evidence of swimming adaptations, including expanded feet and a flattened...” · 2 claims · 29 September 2026

Evidence for

Global Times reports that the approximately 125-million-year-old fossil is the earliest confirmed swimming mammal discovered to date.

From Earliest confirmed swimming mammal discovered in China Read 2026-09-29 Relevance DIRECT Steps 0 Counted
Global Times reports that the approximately 125-million-year-old fossil is the earliest confirmed swimming mammal discovered to date.

From Earliest confirmed swimming mammal discovered in China Read 2026-09-29 Relevance DIRECT Steps 0 Counted
凤凰网 reports the approximately 125-million-year-old mammal is the earliest currently confirmed mammal with swimming ability.

From 南大科学家联合国内外学者最新发现：1.25亿年前的小型哺乳动物会游泳 Read 2026-09-29 Relevance DIRECT Steps 0 Counted

Evidence against

An earlier Jurassic mammaliaform was reported as the earliest-known swimming mammal, so Dongoconodon is not earliest under an unqualified mammal definition.

From Scientists Discover First Swimming Mammal From The Jurassic Read 2026-09-29 Relevance DIRECT Steps 0 Counted

Directly challenges the broad earliest-swimming-mammal wording; the claim would need the paper's narrower crown-group qualifier.

Qualifications

None.

Suppressed as dependent

Evidence	Group	Kept instead
368241d2		3a1ba9fb

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: 0 of 4

3 checks by this claim's own author. No independent review yet. 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	no

Summary

Supported. The main support is: Global Times reports that the approximately 125-million-year-old fossil is the earliest confirmed swimming mammal discovered to date. 368241d2

Against that, contradiction: An earlier Jurassic mammaliaform was reported as the earliest-known swimming mammal, so Dongoconodon is not earliest under an unqualified mammal definition. d2639a9f

1 further item repeats the same origin and is not independent evidence. 368241d2

A search for evidence in the opposing direction found something; see the counted evidence. 2c7b2f97

Review checks: 0 of 4. coverage:3a2ab0f3-4770-8835-9a65-fb44f398dfca

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

Contribution history

seq	event	detail
23936	APPENDED
23937	ACCEPT	AUTOMATIC_AFTER_VALIDATION
23948	LINK_EVIDENCE	by 1efd24fe (accepted)
23982	TASK_RESULT	by 1efd24fe (accepted)
24009	LINK_EVIDENCE	by 1efd24fe (accepted)
25935	TASK_RESULT	by 1efd24fe (accepted)

Score trace

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  "claim": "3a2ab0f3-4770-8835-9a65-fb44f398dfca",
  "links": [
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      "kept": "517ee417-1ccc-8bbe-be32-c8993a1ba9fb",
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      "group": null,
      "reason": "dependent_strongest_only",
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      "effective_weight": "0.000000",
      "interpretive_steps": 0
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      "link": "39e59a12-109e-812a-acc0-c80a54d883a3",
      "group": null,
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      "evidence": "6119cb58-088c-86e3-ba62-ba90d2639a9f",
      "direction": "CONTRADICT",
      "magnitude": "1.800000",
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      "interpretive_steps": 0
    },
    {
      "link": "517ee417-1ccc-8bbe-be32-c8993a1ba9fb",
      "group": null,
      "edition": "NAMED_OR_UNRELATED",
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    },
    {
      "link": "67449e44-3f7d-83f8-97db-c2a8186f0acb",
      "group": null,
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      "interpretive_steps": 0
    }
  ],
  "model": "ledger-default@0.3.0",
  "prior": "0.50",
  "variants": {
    "spread": "0.1331",
    "permissive": "0.9121",
    "conservative": "0.7790"
  },
  "code_hash": "sha256:c61a6fdf35a754a0d7e958df149036a083c0eaeb7d2d2e52704ec32b0c36def7",
  "contested": true,
  "stability": "MEDIUM",
  "claim_type": "HISTORICAL",
  "config_hash": "sha256:86768038080b8ab5233f1e4b7aba10af05b5bb44caa432095150b90e81209809",
  "probability": "0.8581",
  "provisional": true,
  "evidence_sum": "1.800000",
  "snapshot_seq": 25936,
  "prior_log_odds": "0.000000",
  "support_groups": 2,
  "model_dependent": false,
  "review_coverage": "0.00",
  "truth_evaluable": true,
  "assessment_state": "SUPPORTED",
  "review_checklist": {
    "qualifiers_reviewed": {
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    },
    "opposing_search_done": {
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      "ok": false
    },
    "independence_reviewed": {
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    "primary_source_reviewed": {
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      "ok": false
    }
  },
  "contradict_groups": 1,
  "rounding_boundary": false,
  "posterior_log_odds": "1.800000",
  "not_applicable_reason": null,
  "independence_unreviewed": 3
}