diff --git a/CHANGELOG.md b/CHANGELOG.md
index 67e0171..38bb250 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@
   * `WebhooksIn30`: detect root-level `webhooks` usage in 3.0 documents (3.1 addition)
   * `ConstIn30`: detect `const` usage in 3.0 documents (3.1 addition)
   * `DynamicRefIn30`: detect `$dynamicRef` usage in 3.0 documents (3.1 addition)
+  * `DynamicAnchorIn30`: detect `$dynamicAnchor` usage in 3.0 documents (3.1 addition)
 * support 3.1-style numeric `exclusiveMinimum` / `exclusiveMaximum` in value validation (standalone bound, not a Boolean modifier on `minimum` / `maximum`)
 * support `type: "null"` (3.1 primitive) in value validation
 * support root-level `webhooks` (OpenAPI 3.1) in the parse layer
diff --git a/lib/openapi_parser/spec_validator.rb b/lib/openapi_parser/spec_validator.rb
index f239dec..dfee7ca 100644
--- a/lib/openapi_parser/spec_validator.rb
+++ b/lib/openapi_parser/spec_validator.rb
@@ -12,6 +12,7 @@
 require_relative 'spec_validator/rules/webhooks_in_30'
 require_relative 'spec_validator/rules/const_in_30'
 require_relative 'spec_validator/rules/dynamic_ref_in_30'
+require_relative 'spec_validator/rules/dynamic_anchor_in_30'
 
 module OpenAPIParser
   class SpecViolationError < OpenAPIError
@@ -71,6 +72,7 @@ def rules
           Rules::WebhooksIn30,
           Rules::ConstIn30,
           Rules::DynamicRefIn30,
+          Rules::DynamicAnchorIn30,
         ]
       end
   end
diff --git a/lib/openapi_parser/spec_validator/rules/dynamic_anchor_in_30.rb b/lib/openapi_parser/spec_validator/rules/dynamic_anchor_in_30.rb
new file mode 100644
index 0000000..a42ce5f
--- /dev/null
+++ b/lib/openapi_parser/spec_validator/rules/dynamic_anchor_in_30.rb
@@ -0,0 +1,25 @@
+module OpenAPIParser
+  class SpecValidator
+    module Rules
+      # `$dynamicAnchor` is the companion of `$dynamicRef` from JSON Schema
+      # 2020-12, declaring the dynamic resolution point. 3.0 has nothing
+      # equivalent; the rule flags it on 3.0 documents.
+      class DynamicAnchorIn30 < Rule
+        def check(root)
+          return [] unless version == :v3_0
+
+          violations = []
+          each_schema(root) do |schema|
+            next unless schema.raw_schema.is_a?(Hash) && schema.raw_schema.key?('$dynamicAnchor')
+
+            violations << violation(
+              path: schema.object_reference,
+              message: '`$dynamicAnchor` is a 3.1 addition (from JSON Schema 2020-12); 3.0 has no equivalent',
+            )
+          end
+          violations
+        end
+      end
+    end
+  end
+end
diff --git a/sig/openapi_parser/spec_validator.rbs b/sig/openapi_parser/spec_validator.rbs
index c634973..fca7c80 100644
--- a/sig/openapi_parser/spec_validator.rbs
+++ b/sig/openapi_parser/spec_validator.rbs
@@ -84,6 +84,10 @@ module OpenAPIParser
       class DynamicRefIn30 < Rule
         def check: (OpenAPIParser::Schemas::OpenAPI root) -> Array[SpecValidator::SpecViolation]
       end
+
+      class DynamicAnchorIn30 < Rule
+        def check: (OpenAPIParser::Schemas::OpenAPI root) -> Array[SpecValidator::SpecViolation]
+      end
     end
   end
 
diff --git a/spec/data/openapi_3_1/dynamic_anchor_30.yaml b/spec/data/openapi_3_1/dynamic_anchor_30.yaml
new file mode 100644
index 0000000..477b517
--- /dev/null
+++ b/spec/data/openapi_3_1/dynamic_anchor_30.yaml
@@ -0,0 +1,25 @@
+openapi: 3.0.3
+info:
+  title: Tree API
+  version: '1.0'
+paths:
+  /trees:
+    get:
+      summary: Fetch a tree
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Node'
+components:
+  schemas:
+    Node:
+      type: object
+      # `$dynamicAnchor` is a JSON Schema 2020-12 dynamic resolution point
+      # adopted by 3.1; 3.0 has no equivalent, so this is a spec violation.
+      $dynamicAnchor: node
+      properties:
+        label:
+          type: string
diff --git a/spec/data/openapi_3_1/dynamic_anchor_31.yaml b/spec/data/openapi_3_1/dynamic_anchor_31.yaml
new file mode 100644
index 0000000..935d0e0
--- /dev/null
+++ b/spec/data/openapi_3_1/dynamic_anchor_31.yaml
@@ -0,0 +1,25 @@
+openapi: 3.1.0
+info:
+  title: Tree API
+  version: '1.0'
+paths:
+  /trees:
+    get:
+      summary: Fetch a tree
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Node'
+components:
+  schemas:
+    Node:
+      type: object
+      # `$dynamicAnchor` is legitimate under 3.1 (JSON Schema 2020-12), so no
+      # violation is expected here.
+      $dynamicAnchor: node
+      properties:
+        label:
+          type: string
diff --git a/spec/openapi_parser/spec_validator/integration_3_1_spec.rb b/spec/openapi_parser/spec_validator/integration_3_1_spec.rb
index 53fb8f4..183a787 100644
--- a/spec/openapi_parser/spec_validator/integration_3_1_spec.rb
+++ b/spec/openapi_parser/spec_validator/integration_3_1_spec.rb
@@ -212,4 +212,18 @@ def expect_clean(file)
       expect_clean('dynamic_ref_31.yaml')
     end
   end
+
+  describe '$dynamicAnchor (JSON Schema 2020-12 referencing new in 3.1)' do
+    it 'warns on the version-mismatched document under :warn' do
+      expect_mismatch_warns('dynamic_anchor_30.yaml', [:dynamic_anchor_in30])
+    end
+
+    it 'raises SpecViolationError on the version-mismatched document under :raise' do
+      expect_mismatch_raises('dynamic_anchor_30.yaml', [:dynamic_anchor_in30])
+    end
+
+    it 'stays clean on the correctly-versioned document' do
+      expect_clean('dynamic_anchor_31.yaml')
+    end
+  end
 end
diff --git a/spec/openapi_parser/spec_validator/rules/dynamic_anchor_in_30_spec.rb b/spec/openapi_parser/spec_validator/rules/dynamic_anchor_in_30_spec.rb
new file mode 100644
index 0000000..10c6707
--- /dev/null
+++ b/spec/openapi_parser/spec_validator/rules/dynamic_anchor_in_30_spec.rb
@@ -0,0 +1,64 @@
+require_relative '../../../spec_helper'
+
+RSpec.describe 'OpenAPIParser::SpecValidator::Rules::DynamicAnchorIn30' do
+  def base_doc(openapi_version_string, sample_schema)
+    {
+      'openapi' => openapi_version_string,
+      'info' => { 'title' => 'test', 'version' => '1.0' },
+      'paths' => {},
+      'components' => { 'schemas' => { 'Sample' => sample_schema } },
+    }
+  end
+
+  def doc_with_dynamic_anchor(openapi_version_string)
+    raw = base_doc(openapi_version_string, { '$dynamicAnchor' => 'meta' })
+    OpenAPIParser.parse(raw, strict_reference_validation: false)
+  end
+
+  def doc_without_dynamic_anchor(openapi_version_string)
+    raw = base_doc(openapi_version_string, { 'type' => 'string' })
+    OpenAPIParser.parse(raw, strict_reference_validation: false)
+  end
+
+  def run_rule_for(root)
+    OpenAPIParser::SpecValidator::Rules::DynamicAnchorIn30.new(root.openapi_version).check(root)
+  end
+
+  context 'with a 3.1 document using $dynamicAnchor' do
+    it 'reports no violation' do
+      root = doc_with_dynamic_anchor('3.1.0')
+      expect(run_rule_for(root)).to eq []
+    end
+  end
+
+  context 'with a 3.1 document without $dynamicAnchor' do
+    it 'reports no violation' do
+      root = doc_without_dynamic_anchor('3.1.0')
+      expect(run_rule_for(root)).to eq []
+    end
+  end
+
+  context 'with a 3.0 document using $dynamicAnchor' do
+    it 'reports one violation pointing at the offending schema' do
+      root = doc_with_dynamic_anchor('3.0.0')
+      violations = run_rule_for(root)
+      expect(violations.size).to eq 1
+      expect(violations.first.path).to eq '#/components/schemas/Sample'
+      expect(violations.first.rule_name).to eq :dynamic_anchor_in30
+    end
+  end
+
+  context 'with a 3.0 document without $dynamicAnchor' do
+    it 'reports no violation' do
+      root = doc_without_dynamic_anchor('3.0.0')
+      expect(run_rule_for(root)).to eq []
+    end
+  end
+
+  context 'with an :unknown version document' do
+    it 'reports no violation (rule skipped)' do
+      root = doc_with_dynamic_anchor('4.0.0')
+      expect(run_rule_for(root)).to eq []
+    end
+  end
+end