diff --git a/triangulate/src/triangulate.rs b/triangulate/src/triangulate.rs
index ad4ba6e..726089e 100644
--- a/triangulate/src/triangulate.rs
+++ b/triangulate/src/triangulate.rs
@@ -124,6 +124,13 @@ pub fn triangulate(s: &StepFile) -> (Mesh, Stats) {
                 Entity::AdvancedBrepShapeRepresentation(b) => &b.items,
                 Entity::ShapeRepresentation(b) => &b.items,
                 Entity::ManifoldSurfaceShapeRepresentation(b) => &b.items,
+                Entity::GeometricallyBoundedSurfaceShapeRepresentation(_) => {
+                    warn!(
+                        "Skipping unsupported GeometricallyBoundedSurfaceShapeRepresentation #{}",
+                        id.0
+                    );
+                    continue;
+                }
                 e => panic!("Could not get shape from {:?}", e),
             };
 
diff --git a/triangulate/tests/fixtures/unsupported_geometrically_bounded_surface.step b/triangulate/tests/fixtures/unsupported_geometrically_bounded_surface.step
new file mode 100644
index 0000000..b63b623
--- /dev/null
+++ b/triangulate/tests/fixtures/unsupported_geometrically_bounded_surface.step
@@ -0,0 +1,441 @@
+ISO-10303-21;
+HEADER;
+FILE_DESCRIPTION(('Open CASCADE Model'),'2;1');
+FILE_NAME('Open CASCADE Shape Model','2021-05-17T18:28:03',('Author'),(
+    'Open CASCADE'),'Open CASCADE STEP processor 6.8','Open CASCADE 6.8'
+  ,'Unknown');
+FILE_SCHEMA(('AUTOMOTIVE_DESIGN { 1 0 10303 214 1 1 1 1 }'));
+ENDSEC;
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+#311 = ( NAMED_UNIT(*) PLANE_ANGLE_UNIT() SI_UNIT($,.RADIAN.) );
+#312 = ( NAMED_UNIT(*) SI_UNIT($,.STERADIAN.) SOLID_ANGLE_UNIT() );
+#313 = UNCERTAINTY_MEASURE_WITH_UNIT(LENGTH_MEASURE(1.E-007),#310,
+  'distance_accuracy_value','confusion accuracy');
+#314 = SHAPE_DEFINITION_REPRESENTATION(#315,#255);
+#315 = PRODUCT_DEFINITION_SHAPE('','',#316);
+#316 = PRODUCT_DEFINITION('design','',#317,#320);
+#317 = PRODUCT_DEFINITION_FORMATION('','',#318);
+#318 = PRODUCT('Cylinder','Cylinder','',(#319));
+#319 = PRODUCT_CONTEXT('',#2,'mechanical');
+#320 = PRODUCT_DEFINITION_CONTEXT('part definition',#2,'design');
+#321 = CONTEXT_DEPENDENT_SHAPE_REPRESENTATION(#322,#324);
+#322 = ( REPRESENTATION_RELATIONSHIP('','',#255,#245)
+REPRESENTATION_RELATIONSHIP_WITH_TRANSFORMATION(#323)
+SHAPE_REPRESENTATION_RELATIONSHIP() );
+#323 = ITEM_DEFINED_TRANSFORMATION('','',#11,#246);
+#324 = PRODUCT_DEFINITION_SHAPE('Placement','Placement of an item',#325
+  );
+#325 = NEXT_ASSEMBLY_USAGE_OCCURRENCE('3','3','',#240,#316,$);
+#326 = PRODUCT_RELATED_PRODUCT_CATEGORY('part',$,(#318));
+#327 = CONTEXT_DEPENDENT_SHAPE_REPRESENTATION(#328,#330);
+#328 = ( REPRESENTATION_RELATIONSHIP('','',#245,#228)
+REPRESENTATION_RELATIONSHIP_WITH_TRANSFORMATION(#329)
+SHAPE_REPRESENTATION_RELATIONSHIP() );
+#329 = ITEM_DEFINED_TRANSFORMATION('','',#11,#229);
+#330 = PRODUCT_DEFINITION_SHAPE('Placement','Placement of an item',#331
+  );
+#331 = NEXT_ASSEMBLY_USAGE_OCCURRENCE('4','','',#223,#240,$);
+#332 = PRODUCT_RELATED_PRODUCT_CATEGORY('part',$,(#242));
+#333 = CONTEXT_DEPENDENT_SHAPE_REPRESENTATION(#334,#336);
+#334 = ( REPRESENTATION_RELATIONSHIP('','',#228,#10)
+REPRESENTATION_RELATIONSHIP_WITH_TRANSFORMATION(#335)
+SHAPE_REPRESENTATION_RELATIONSHIP() );
+#335 = ITEM_DEFINED_TRANSFORMATION('','',#11,#19);
+#336 = PRODUCT_DEFINITION_SHAPE('Placement','Placement of an item',#337
+  );
+#337 = NEXT_ASSEMBLY_USAGE_OCCURRENCE('5','','',#5,#223,$);
+#338 = PRODUCT_RELATED_PRODUCT_CATEGORY('part',$,(#225));
+#339 = SHAPE_DEFINITION_REPRESENTATION(#324,#340);
+#340 = SHAPE_REPRESENTATION('',(#246),#309);
+#341 = MECHANICAL_DESIGN_GEOMETRIC_PRESENTATION_REPRESENTATION('',(#342,
+    #352),#309);
+#342 = STYLED_ITEM('color',(#343),#256);
+#343 = PRESENTATION_STYLE_ASSIGNMENT((#344,#350));
+#344 = SURFACE_STYLE_USAGE(.BOTH.,#345);
+#345 = SURFACE_SIDE_STYLE('',(#346));
+#346 = SURFACE_STYLE_FILL_AREA(#347);
+#347 = FILL_AREA_STYLE('',(#348));
+#348 = FILL_AREA_STYLE_COLOUR('',#349);
+#349 = COLOUR_RGB('',0.501960813999,0.501960813999,0.501960813999);
+#350 = CURVE_STYLE('',#351,POSITIVE_LENGTH_MEASURE(0.1),#349);
+#351 = DRAUGHTING_PRE_DEFINED_CURVE_FONT('continuous');
+#352 = OVER_RIDING_STYLED_ITEM('overriding color',(#353),#256,#342);
+#353 = PRESENTATION_STYLE_BY_CONTEXT((#354,#360),#340);
+#354 = SURFACE_STYLE_USAGE(.BOTH.,#355);
+#355 = SURFACE_SIDE_STYLE('',(#356));
+#356 = SURFACE_STYLE_FILL_AREA(#357);
+#357 = FILL_AREA_STYLE('',(#358));
+#358 = FILL_AREA_STYLE_COLOUR('',#359);
+#359 = COLOUR_RGB('',0.501960813999,0.501960813999,0.501960813999);
+#360 = CURVE_STYLE('',#361,POSITIVE_LENGTH_MEASURE(0.1),#359);
+#361 = DRAUGHTING_PRE_DEFINED_CURVE_FONT('continuous');
+#362 = MECHANICAL_DESIGN_GEOMETRIC_PRESENTATION_REPRESENTATION('',(#363)
+  ,#197);
+#363 = STYLED_ITEM('color',(#364),#47);
+#364 = PRESENTATION_STYLE_ASSIGNMENT((#365,#371));
+#365 = SURFACE_STYLE_USAGE(.BOTH.,#366);
+#366 = SURFACE_SIDE_STYLE('',(#367));
+#367 = SURFACE_STYLE_FILL_AREA(#368);
+#368 = FILL_AREA_STYLE('',(#369));
+#369 = FILL_AREA_STYLE_COLOUR('',#370);
+#370 = COLOUR_RGB('',0.141176477075,0.470588237047,0.196078434587);
+#371 = CURVE_STYLE('',#372,POSITIVE_LENGTH_MEASURE(0.1),#370);
+#372 = DRAUGHTING_PRE_DEFINED_CURVE_FONT('continuous');
+#373 = SHAPE_REPRESENTATION_RELATIONSHIP('','',#10,#384);
+#374 = CARTESIAN_POINT('',(0.E+000,0.E+000,0.E+000));
+#375 = DIRECTION('',(0.E+000,0.E+000,1.));
+#376 = DIRECTION('',(1.,0.E+000,0.E+000));
+#377 = AXIS2_PLACEMENT_3D('',#374,#375,#376);
+#378 = DIRECTION('',(0.E+000,1.,0.E+000));
+#379 = VECTOR('',#378,1.);
+#380 = CARTESIAN_POINT('',(0.E+000,0.E+000,0.E+000));
+#381 = LINE('',#380,#379);
+#382 = TRIMMED_CURVE('',#381,(PARAMETER_VALUE(0.)),
+  (PARAMETER_VALUE(1.)),.T.,.UNSPECIFIED.);
+#383 = GEOMETRIC_SET('',(#382));
+#384 = GEOMETRICALLY_BOUNDED_SURFACE_SHAPE_REPRESENTATION('',
+  (#377,#383),#23);
+ENDSEC;
+END-ISO-10303-21;
diff --git a/triangulate/tests/representation_fallback.rs b/triangulate/tests/representation_fallback.rs
new file mode 100644
index 0000000..a943f2f
--- /dev/null
+++ b/triangulate/tests/representation_fallback.rs
@@ -0,0 +1,33 @@
+use step::{ap214::Entity, step_file::StepFile};
+use triangulate::triangulate::triangulate;
+
+fn mesh_counts(data: &[u8]) -> (usize, usize) {
+    let flat = StepFile::strip_flatten(data);
+    let entities = StepFile::parse(&flat);
+    assert!(entities.0.iter().any(|entity| matches!(
+        entity,
+        Entity::GeometricallyBoundedSurfaceShapeRepresentation(_)
+    )));
+    let (mesh, _) = triangulate(&entities);
+    (mesh.verts.len(), mesh.triangles.len())
+}
+
+#[test]
+fn skips_unsupported_geometrically_bounded_surface_representation() {
+    let baseline_data = include_bytes!("../../examples/abstract_pca.step");
+    let flat = StepFile::strip_flatten(baseline_data);
+    let baseline_entities = StepFile::parse(&flat);
+    assert!(!baseline_entities.0.iter().any(|entity| matches!(
+        entity,
+        Entity::GeometricallyBoundedSurfaceShapeRepresentation(_)
+    )));
+    let (baseline_mesh, _) = triangulate(&baseline_entities);
+    let baseline = (baseline_mesh.verts.len(), baseline_mesh.triangles.len());
+
+    let with_auxiliary_geometry = mesh_counts(include_bytes!(
+        "fixtures/unsupported_geometrically_bounded_surface.step"
+    ));
+
+    assert_ne!(baseline, (0, 0));
+    assert_eq!(with_auxiliary_geometry, baseline);
+}