Dumblea symmetrica Cragin, 1893
Plate: DuSy-10
Series: Upper Cretaceous Group: Washita Formation: Fort Worth
Locale: Krum County: Denton Stage: Albian
Length: 40.6 mm Height: 29.0 mm
Specimen in photo: Collection of Frank Crane
Repository: Private Collection
HOLOTYPE INFO:
Holotype: Geological Survey of Texas Collection (Cragin, 1893); Likely housed at Non-vertebrate Paleontology Lab, University of Texas (Austin).
Locality: Sierra Blanca Mountains, Hudspeth/Culberson Counties, Texas (Cragin, 1893)
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Echinacea Claus, 1876
Order: Pedinoida Mortensen, 1939
Family: Pedinopsidae Durham, 1966
Genus: DUMBLEA Cragin, 1893
Species: Dumblea symmetrica Cragin, 1893
TYPE SPECIES: Dumblea symmetrica Cragin, 1893 (Monotypic)
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita (Cragin, 1893; Cooke, 1955)
Formations: Fort Worth Limestone (Header); Georgetown Limestone, Weno Clay (Cooke, 1955); Boracho Formation
Stratigraphic Units: Lower/Upper Cretaceous boundary, Late Albian (Cooke, 1955)
Counties: Denton (Header), Tarrant, Hudspeth/Culberson (Sierra Blanca) (Cragin, 1893)
DESCRIPTION
TOP: Length, width, height: 40.6 mm L × 29.0 mm H (Frank Crane Specimen); Cragin Type: 45 mm W × 31.5 mm H.
Top shape: Subspherical; form comparable to an onion bulb or small tomato (Cragin, 1893); Circular outline, incipiently 15-lobed due to constrictions (Cragin, 1893)
Top domed: Subglobular (Cooke, 1955)
BOTTOM: Bottom shape: Flattened or concave around the peristome (Cooke, 1955)
AMB: Amb shape: Regularly expanding; about half as wide as interambulacra (Cooke, 1955)
Amb arrangement: Compound plates short and wide, including one primary and two demiplates (3 elements) (Cooke, 1955)
Amb primary tubercles: 2 to 4 tubercles in a series on an ambulacral plate (Cragin, 1893)
INTERAMB: Interamb plating: Short, wide, straight; about 1.5 times as high as ambulacral plates (Cooke, 1955)
Interamb primary tubercles: 7 to 9 tubercles in a series on an interambulacral plate; frequently 2 or 3 extra-serial tubercles near outer end (Cragin, 1893)
PORE PAIRS: Arrangement: Biserial; somewhat disarranged below the ambitus, slightly expanding near peristome (Cooke, 1955)
Geminate count: Three pairs of pores per compound plate (Cooke, 1955)
TUBERCLES: Primary tubercles: Alike on ambulacra and interambulacra; arranged in a single more or less devious linear series on each plate (Cragin, 1893)
Primary Perforated: Yes (Cooke, 1955)
Primary Crenulate: Yes (Minutely) (Cooke, 1955)
Secondary tubercles: Arranged partly in imperfect ring-like groups about the primary (Cragin, 1893)
APICAL SYSTEM: Size: Small (Cooke, 1955); Breadth 6 mm in type (Cragin, 1893)
Shape: Subcircular with projecting points; 3 exsert oculars, 2 insert (Cooke, 1955)
Madreporite: Large, swollen (Cooke, 1955)
PERIPROCT (ANUS): Shape & Size: Subovate; moderate size (Cragin, 1893)
Location: Central or slightly excentric (Cooke, 1955)
Plating: One (sometimes two) deeply notched ocular plates entering its boundary (Cragin, 1893)
PERISTOME (MOUTH): Size: Small; little more than 1/4 diameter (Cooke, 1955); Breadth 13 mm in type (Cragin, 1893)
Shape: Subcircular (Cragin, 1893)
Lip: Strongly notched; 10 pronounced interambulacral and 5 shallow ambulacral emarginations (Cragin, 1893)
SPECIMENS STUDIED & CONDITION: Specimen in Frank Crane collection (DuSy-10); Small specimen (17.4 mm) in Kevin Durney collection (Weno Fm).
ETYMOLOGY: The genus Dumblea is named for E. T. Dumble (1852–1927), the State Geologist of Texas. The species symmetrica refers to the regular, symmetrical shape of the test.
REMARKS & COMPARISONS
Remarks: Specimens from the Boracho Formation are noted to be more spherical than those from the Fort Worth Formation.
Comparisons: Dumblea differs from Pedinopsis by the shape/arrangement of compound ambulacral plates (lower, 3 pore pairs vs. 6). It is similar to Micropedina but differs in the biserial arrangement of pore pairs (vs. inclined groups of three in Micropedina) and spreading near the peristome (Cooke, 1955).
Plate: DuSy-10
Series: Upper Cretaceous Group: Washita Formation: Fort Worth
Locale: Krum County: Denton Stage: Albian
Length: 40.6 mm Height: 29.0 mm
Specimen in photo: Collection of Frank Crane
Repository: Private Collection
HOLOTYPE INFO:
Holotype: Geological Survey of Texas Collection (Cragin, 1893); Likely housed at Non-vertebrate Paleontology Lab, University of Texas (Austin).
Locality: Sierra Blanca Mountains, Hudspeth/Culberson Counties, Texas (Cragin, 1893)
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Echinacea Claus, 1876
Order: Pedinoida Mortensen, 1939
Family: Pedinopsidae Durham, 1966
Genus: DUMBLEA Cragin, 1893
Species: Dumblea symmetrica Cragin, 1893
TYPE SPECIES: Dumblea symmetrica Cragin, 1893 (Monotypic)
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita (Cragin, 1893; Cooke, 1955)
Formations: Fort Worth Limestone (Header); Georgetown Limestone, Weno Clay (Cooke, 1955); Boracho Formation
Stratigraphic Units: Lower/Upper Cretaceous boundary, Late Albian (Cooke, 1955)
Counties: Denton (Header), Tarrant, Hudspeth/Culberson (Sierra Blanca) (Cragin, 1893)
DESCRIPTION
TOP: Length, width, height: 40.6 mm L × 29.0 mm H (Frank Crane Specimen); Cragin Type: 45 mm W × 31.5 mm H.
Top shape: Subspherical; form comparable to an onion bulb or small tomato (Cragin, 1893); Circular outline, incipiently 15-lobed due to constrictions (Cragin, 1893)
Top domed: Subglobular (Cooke, 1955)
BOTTOM: Bottom shape: Flattened or concave around the peristome (Cooke, 1955)
AMB: Amb shape: Regularly expanding; about half as wide as interambulacra (Cooke, 1955)
Amb arrangement: Compound plates short and wide, including one primary and two demiplates (3 elements) (Cooke, 1955)
Amb primary tubercles: 2 to 4 tubercles in a series on an ambulacral plate (Cragin, 1893)
INTERAMB: Interamb plating: Short, wide, straight; about 1.5 times as high as ambulacral plates (Cooke, 1955)
Interamb primary tubercles: 7 to 9 tubercles in a series on an interambulacral plate; frequently 2 or 3 extra-serial tubercles near outer end (Cragin, 1893)
PORE PAIRS: Arrangement: Biserial; somewhat disarranged below the ambitus, slightly expanding near peristome (Cooke, 1955)
Geminate count: Three pairs of pores per compound plate (Cooke, 1955)
TUBERCLES: Primary tubercles: Alike on ambulacra and interambulacra; arranged in a single more or less devious linear series on each plate (Cragin, 1893)
Primary Perforated: Yes (Cooke, 1955)
Primary Crenulate: Yes (Minutely) (Cooke, 1955)
Secondary tubercles: Arranged partly in imperfect ring-like groups about the primary (Cragin, 1893)
APICAL SYSTEM: Size: Small (Cooke, 1955); Breadth 6 mm in type (Cragin, 1893)
Shape: Subcircular with projecting points; 3 exsert oculars, 2 insert (Cooke, 1955)
Madreporite: Large, swollen (Cooke, 1955)
PERIPROCT (ANUS): Shape & Size: Subovate; moderate size (Cragin, 1893)
Location: Central or slightly excentric (Cooke, 1955)
Plating: One (sometimes two) deeply notched ocular plates entering its boundary (Cragin, 1893)
PERISTOME (MOUTH): Size: Small; little more than 1/4 diameter (Cooke, 1955); Breadth 13 mm in type (Cragin, 1893)
Shape: Subcircular (Cragin, 1893)
Lip: Strongly notched; 10 pronounced interambulacral and 5 shallow ambulacral emarginations (Cragin, 1893)
SPECIMENS STUDIED & CONDITION: Specimen in Frank Crane collection (DuSy-10); Small specimen (17.4 mm) in Kevin Durney collection (Weno Fm).
ETYMOLOGY: The genus Dumblea is named for E. T. Dumble (1852–1927), the State Geologist of Texas. The species symmetrica refers to the regular, symmetrical shape of the test.
REMARKS & COMPARISONS
Remarks: Specimens from the Boracho Formation are noted to be more spherical than those from the Fort Worth Formation.
Comparisons: Dumblea differs from Pedinopsis by the shape/arrangement of compound ambulacral plates (lower, 3 pore pairs vs. 6). It is similar to Micropedina but differs in the biserial arrangement of pore pairs (vs. inclined groups of three in Micropedina) and spreading near the peristome (Cooke, 1955).
