Conulus stephensoni Cooke, 1953
Plate: CoSt-10
Series: Upper Cretaceous Group: Austin Formation: Austin Chalk
Locale: Austin County: Travis Stage: Santonian
Length: 36.6 mm Width: 32.7 mm Height: 21.7 mm
Specimen in photo: Collection of Ed Elliott
Repository: Private Collection
HOLOTYPE INFO:
Holotype: USNM 108365 (Holotype) — National Museum of Natural History, Smithsonian Institution (Cooke, 1953)
Locality: E.W. Berry's Locality 2, near Austin, Travis County, Texas (Cooke, 1953)
DIAGNOSIS
Test large; subpentagonal to ovate horizontal outline, broadest at the anterior paired ambulacra. Upper surface moderately inflated; lower surface nearly flat. Apical system central with four genital plates; madreporite confined to anterior. Periproct large, lenticular, inframarginal (Cooke, 1953).
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Echinoneidea Kroh & Smith, 2010
Order: Echinoneoida H. L. Clark, 1925
Family: Conulidae Lambert, 1911
Genus: CONULUS Leske, 1778
Species: Conulus stephensoni Cooke, 1953
TYPE SPECIES: Conulus albogalerus Leske, 1778
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Austin
Formations: Austin Chalk (Cooke, 1953)
Stratigraphic Units: Upper Cretaceous, Santonian (Cooke, 1953)
Counties: Travis County
DESCRIPTION
TOP: Length, width, height: 36.6 mm L × 32.7 mm W × 21.7 mm H
Top shape: Subpentagonal to ovate; broadest at the anterior paired ambulacra (Cooke, 1953)
Top domed: Upper surface moderately inflated (Cooke, 1953)
SIDE: Ambitus: Margin rounded (Cooke, 1953)
BOTTOM: Bottom flat: Lower surface nearly flat (Cooke, 1953)
AMB: Amb width: Narrow; one-third as wide as the interambulacra (Cooke, 1953)
Amb primary zones: Poriferous zones continuous; divided into oblique triads on the under surface (Cooke, 1953)
TUBERCLES: Primary tubercles: Large, in deep pits (Cooke, 1953)
Density variation: Not very close together on the underside; still farther apart on the upper side (Cooke, 1953)
APICAL SYSTEM: Location: Central (Cooke, 1953)
Plates: Ocular plates large, posterior pair in contact; only four genital plates, posterior pair in contact (Cooke, 1953)
Madreporite: Confined to the anterior part of the system (Cooke, 1953)
PERIPROCT (ANUS): Shape & Size: Large, lenticular (Cooke, 1953)
Location: Inframarginal; extending halfway to the peristome (Cooke, 1953)
Visibility: Not visible from above (Cooke, 1953)
PERISTOME (MOUTH): Shape: Nearly symmetrical; longer axis turned clockwise with respect to the longitudinal axis of the test (Cooke, 1953)
SPECIMENS STUDIED & CONDITION: Specimen CoSt-10 in collection of Ed Elliott
ETYMOLOGY: Named in honor of Lloyd W. Stephenson (1876–1962), a paleontologist with the U.S. Geological Survey known for his work on the Texas Upper Cretaceous (Cooke, 1953).
REMARKS & COMPARISONS
Remarks: This species is assigned to Conulus based on the inframarginal periproct and characteristic apical system.
Comparisons: Conulus stephensoni differs from Globator vaughani Cooke in its greater size, less rotund shape, details of the apical plate arrangement, location of the periproct, wider spacing of tubercles, and narrower ambulacra (Cooke, 1953).
Plate: CoSt-10
Series: Upper Cretaceous Group: Austin Formation: Austin Chalk
Locale: Austin County: Travis Stage: Santonian
Length: 36.6 mm Width: 32.7 mm Height: 21.7 mm
Specimen in photo: Collection of Ed Elliott
Repository: Private Collection
HOLOTYPE INFO:
Holotype: USNM 108365 (Holotype) — National Museum of Natural History, Smithsonian Institution (Cooke, 1953)
Locality: E.W. Berry's Locality 2, near Austin, Travis County, Texas (Cooke, 1953)
DIAGNOSIS
Test large; subpentagonal to ovate horizontal outline, broadest at the anterior paired ambulacra. Upper surface moderately inflated; lower surface nearly flat. Apical system central with four genital plates; madreporite confined to anterior. Periproct large, lenticular, inframarginal (Cooke, 1953).
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Echinoneidea Kroh & Smith, 2010
Order: Echinoneoida H. L. Clark, 1925
Family: Conulidae Lambert, 1911
Genus: CONULUS Leske, 1778
Species: Conulus stephensoni Cooke, 1953
TYPE SPECIES: Conulus albogalerus Leske, 1778
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Austin
Formations: Austin Chalk (Cooke, 1953)
Stratigraphic Units: Upper Cretaceous, Santonian (Cooke, 1953)
Counties: Travis County
DESCRIPTION
TOP: Length, width, height: 36.6 mm L × 32.7 mm W × 21.7 mm H
Top shape: Subpentagonal to ovate; broadest at the anterior paired ambulacra (Cooke, 1953)
Top domed: Upper surface moderately inflated (Cooke, 1953)
SIDE: Ambitus: Margin rounded (Cooke, 1953)
BOTTOM: Bottom flat: Lower surface nearly flat (Cooke, 1953)
AMB: Amb width: Narrow; one-third as wide as the interambulacra (Cooke, 1953)
Amb primary zones: Poriferous zones continuous; divided into oblique triads on the under surface (Cooke, 1953)
TUBERCLES: Primary tubercles: Large, in deep pits (Cooke, 1953)
Density variation: Not very close together on the underside; still farther apart on the upper side (Cooke, 1953)
APICAL SYSTEM: Location: Central (Cooke, 1953)
Plates: Ocular plates large, posterior pair in contact; only four genital plates, posterior pair in contact (Cooke, 1953)
Madreporite: Confined to the anterior part of the system (Cooke, 1953)
PERIPROCT (ANUS): Shape & Size: Large, lenticular (Cooke, 1953)
Location: Inframarginal; extending halfway to the peristome (Cooke, 1953)
Visibility: Not visible from above (Cooke, 1953)
PERISTOME (MOUTH): Shape: Nearly symmetrical; longer axis turned clockwise with respect to the longitudinal axis of the test (Cooke, 1953)
SPECIMENS STUDIED & CONDITION: Specimen CoSt-10 in collection of Ed Elliott
ETYMOLOGY: Named in honor of Lloyd W. Stephenson (1876–1962), a paleontologist with the U.S. Geological Survey known for his work on the Texas Upper Cretaceous (Cooke, 1953).
REMARKS & COMPARISONS
Remarks: This species is assigned to Conulus based on the inframarginal periproct and characteristic apical system.
Comparisons: Conulus stephensoni differs from Globator vaughani Cooke in its greater size, less rotund shape, details of the apical plate arrangement, location of the periproct, wider spacing of tubercles, and narrower ambulacra (Cooke, 1953).
