Cidaris texanus Clark, 1891
Plate: CiTe-10
Series: Upper Cretaceous Group: Austin or Taylor Formation: Austin Chalk or Anacacho
Locale: Unknown County: Bexar Stage: Unknown
Length: 69.3 mm Height: 25.0 mm (estimate)
Specimen in photo: U.S.N.M. 8381 Holotype
Paleobiology Depart. NMNH, Smithsonian Institution Crushed
Plate: CiTe-20
Series: Upper Cretaceous Group: Unknown Formation: Unknown
Locale: Unknown County: Bexar Stage: Unknown
Length: 69.0 mm Height: 31.3 mm (estimate)
Specimen in photo: Collection of Kevin Durney Crushed
HOLOTYPE INFO:
Holotype: USNM 8381 — National Museum of Natural History, Smithsonian Institution (Clark & Twitchell, 1915)
Locality: Bexar County, Texas (Clark, 1893)
Note: Originally attributed to the Washita Group (Lower Cretaceous), but matrix analysis and subsequent finds suggest an Upper Cretaceous origin (Austin Chalk or Anacacho Limestone) (Clark & Twitchell, 1915; Cooke, 1953).
Systematic Paleontology
CLASS: ECHINOIDEA Leske, 1778
SUBCLASS: CIDAROIDEA Smith, 1984
ORDER: CIDAROIDA Claus, 1880
FAMILY: CIDARIDAE Gray, 1825
GENUS: CIDARIS Leske, 1778
SPECIES: Cidaris texanus Clark, 1891
TYPE SPECIES: Echinus cidaris Linnaeus, 1758
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Uncertain; likely Austin or Taylor (Clark & Twitchell, 1915)
Formations: Austin Chalk? / Anacacho Limestone? (Clark & Twitchell, 1915)
Stratigraphic Units: Upper Cretaceous (Clark & Twitchell, 1915)
Counties: Bexar County (Clark, 1893)
DESCRIPTION
TOP: Top shape: Test large, inflated; somewhat compressed in preservation (Clark, 1893).
AMB: Amb shape: Narrow, slightly undulating (Clark & Twitchell, 1915); Sinuous/flexuous (Clark, 1893).
Amb primary zones: Four rows of granules between poriferous avenues, increasing to six at the ambitus and reducing to two toward the apex/mouth (Clark, 1893).
Pore zones: Pores oval, separated by transverse elevations/granules (Clark, 1893; Clark & Twitchell, 1915).
Zygopores: Slightly inclined (Clark & Twitchell, 1915).
INTERAMB: Interamb plating: Wide; approximately seven plates in each tier (Clark & Twitchell, 1915).
Sutures: Conspicuous (Clark & Twitchell, 1915).
TUBERCLES: Primary tubercles: Large, circular (Clark, 1893); Smooth, perforated, widely separated (Clark & Twitchell, 1915).
Primary Perforated: Yes (Clark, 1893).
Primary Crenulate: No (Implied by "Boss smooth" description in Clark, 1893).
Primary Areola shape: Circular, deeply depressed, radially ridged (Clark, 1893).
Primary Boss: Slightly elevated, smooth (Clark, 1893).
Primary Mamelon: Small, perforated (Clark, 1893).
Secondary tubercles: Row of mammillated granules surrounds the areola (Clark, 1893).
GRANULES: Granules pattern: Miliary space wide, covered with numerous tall/small granules (Clark, 1893; Clark & Twitchell, 1915).
APICAL SYSTEM: Size / Location: Apical scar proportionately small (Clark & Twitchell, 1915).
PERISTOME (MOUTH): Location: Unknown (Clark, 1893).
SPECIMENS STUDIED & CONDITION: Holotype USNM 8381 is crushed (Clark & Twitchell, 1915). Additional crushed specimen in Kevin Durney collection.
ETYMOLOGY: Named for the state of Texas.
REMARKS & COMPARISONS
Remarks: Cidaris texanus was historically confused with Stereocidaris hemigranosus. Clark & Twitchell (1915) distinguished them, noting C. texanus lacks the traits of Stereocidaris (though the radially ridged areola described in 1893 is often a Stereocidaris trait). The stratigraphic origin remains problematic but is almost certainly Upper Cretaceous (Austin/Taylor) rather than Washita (Lower Cretaceous).
Comparisons: Similar to Cidaris sceptrifera Mantell (White Chalk, UK) but differs in ambulacral granule arrangement and the presence of radial ridges in the areola (sceptrifera is smooth). Differs from Cidaris branneri (Brazil) in areola character (Clark, 1893).
Plate: CiTe-10
Series: Upper Cretaceous Group: Austin or Taylor Formation: Austin Chalk or Anacacho
Locale: Unknown County: Bexar Stage: Unknown
Length: 69.3 mm Height: 25.0 mm (estimate)
Specimen in photo: U.S.N.M. 8381 Holotype
Paleobiology Depart. NMNH, Smithsonian Institution Crushed
Plate: CiTe-20
Series: Upper Cretaceous Group: Unknown Formation: Unknown
Locale: Unknown County: Bexar Stage: Unknown
Length: 69.0 mm Height: 31.3 mm (estimate)
Specimen in photo: Collection of Kevin Durney Crushed
HOLOTYPE INFO:
Holotype: USNM 8381 — National Museum of Natural History, Smithsonian Institution (Clark & Twitchell, 1915)
Locality: Bexar County, Texas (Clark, 1893)
Note: Originally attributed to the Washita Group (Lower Cretaceous), but matrix analysis and subsequent finds suggest an Upper Cretaceous origin (Austin Chalk or Anacacho Limestone) (Clark & Twitchell, 1915; Cooke, 1953).
Systematic Paleontology
CLASS: ECHINOIDEA Leske, 1778
SUBCLASS: CIDAROIDEA Smith, 1984
ORDER: CIDAROIDA Claus, 1880
FAMILY: CIDARIDAE Gray, 1825
GENUS: CIDARIS Leske, 1778
SPECIES: Cidaris texanus Clark, 1891
TYPE SPECIES: Echinus cidaris Linnaeus, 1758
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Uncertain; likely Austin or Taylor (Clark & Twitchell, 1915)
Formations: Austin Chalk? / Anacacho Limestone? (Clark & Twitchell, 1915)
Stratigraphic Units: Upper Cretaceous (Clark & Twitchell, 1915)
Counties: Bexar County (Clark, 1893)
DESCRIPTION
TOP: Top shape: Test large, inflated; somewhat compressed in preservation (Clark, 1893).
AMB: Amb shape: Narrow, slightly undulating (Clark & Twitchell, 1915); Sinuous/flexuous (Clark, 1893).
Amb primary zones: Four rows of granules between poriferous avenues, increasing to six at the ambitus and reducing to two toward the apex/mouth (Clark, 1893).
Pore zones: Pores oval, separated by transverse elevations/granules (Clark, 1893; Clark & Twitchell, 1915).
Zygopores: Slightly inclined (Clark & Twitchell, 1915).
INTERAMB: Interamb plating: Wide; approximately seven plates in each tier (Clark & Twitchell, 1915).
Sutures: Conspicuous (Clark & Twitchell, 1915).
TUBERCLES: Primary tubercles: Large, circular (Clark, 1893); Smooth, perforated, widely separated (Clark & Twitchell, 1915).
Primary Perforated: Yes (Clark, 1893).
Primary Crenulate: No (Implied by "Boss smooth" description in Clark, 1893).
Primary Areola shape: Circular, deeply depressed, radially ridged (Clark, 1893).
Primary Boss: Slightly elevated, smooth (Clark, 1893).
Primary Mamelon: Small, perforated (Clark, 1893).
Secondary tubercles: Row of mammillated granules surrounds the areola (Clark, 1893).
GRANULES: Granules pattern: Miliary space wide, covered with numerous tall/small granules (Clark, 1893; Clark & Twitchell, 1915).
APICAL SYSTEM: Size / Location: Apical scar proportionately small (Clark & Twitchell, 1915).
PERISTOME (MOUTH): Location: Unknown (Clark, 1893).
SPECIMENS STUDIED & CONDITION: Holotype USNM 8381 is crushed (Clark & Twitchell, 1915). Additional crushed specimen in Kevin Durney collection.
ETYMOLOGY: Named for the state of Texas.
REMARKS & COMPARISONS
Remarks: Cidaris texanus was historically confused with Stereocidaris hemigranosus. Clark & Twitchell (1915) distinguished them, noting C. texanus lacks the traits of Stereocidaris (though the radially ridged areola described in 1893 is often a Stereocidaris trait). The stratigraphic origin remains problematic but is almost certainly Upper Cretaceous (Austin/Taylor) rather than Washita (Lower Cretaceous).
Comparisons: Similar to Cidaris sceptrifera Mantell (White Chalk, UK) but differs in ambulacral granule arrangement and the presence of radial ridges in the areola (sceptrifera is smooth). Differs from Cidaris branneri (Brazil) in areola character (Clark, 1893).
