Cidaris dixiensis Cragin, 1893
Plate: CiDi-10
Series: Upper Cretaceous Group: Taylor Formation: Taylor Marl
Locale: Dallas County: Dallas Stage: Campanian
Length: 7 mm (plate) Width: 8 mm (plate)
Specimen in photo: old photos only
Repository: Cragin Collection (likely Non-vertebrate Paleo. Lab, Univ. of Texas)
HOLOTYPE INFO:
Holotype: Specimen from the Cragin Collection; presumably housed at the Non-vertebrate Paleontology Laboratory, University of Texas at Austin (Cragin, 1893; Adkins, 1928).
Locality: 9 miles northeast of Dallas, Dallas County, Texas (Cragin, 1893).
Horizon: Contact between the Austin Chalk and the Taylor Marl ("Ponderosa marl") (Cragin, 1893).
Systematic Paleontology
CLASS: ECHINOIDEA Leske, 1778
SUBCLASS: CIDAROIDEA Smith, 1984
ORDER: CIDAROIDA Claus, 1880
FAMILY: CIDARIDAE Gray, 1825
SUBFAMILY: STEREOCIDARINAE Lambert, 1900
GENUS: CIDARIS Leske, 1778
SPECIES: Cidaris dixiensis Cragin, 1893
TYPE SPECIES: Echinus cidaris Linnaeus, 1758
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Taylor (Cragin, 1893)
Formations: Taylor Marl (Clark & Twitchell, 1915)
Stratigraphic Units: Upper Cretaceous, Campanian (Cragin, 1893)
Counties: Dallas County (Cragin, 1893)
DESCRIPTION
TOP: Length, width: 7 mm L × 8 mm W (Interambulacral plate dimensions) (Cragin, 1893)
Top shape: Test rather small, thin (Cragin, 1893)
INTERAMB: Interamb plate shape: Plates described as isolated; size indicates form was likely not large (Clark & Twitchell, 1915)
Interamb granules: Ornamented with crowded, rounded granules; granules increase in size toward the areola (Cragin, 1893)
Granule arrangement: Largest granules form an alternating double row around the areola (Cragin, 1893)
TUBERCLES: Primary tubercles: Rather small and feebly elevated. Perforated. (Cragin, 1893)
Primary Crenulate: No (Cragin, 1893)
Primary Boss: Smooth; feebly elevated (Clark & Twitchell, 1915)
Primary Areola shape: Feebly depressed (Cragin, 1893)
Primary Mamelon: Small and perforated (Clark & Twitchell, 1915)
GRANULES: Granules pattern: Miliary space relatively narrow; covered with granules larger toward the areola (Clark & Twitchell, 1915)
SPINES: Shape: Unknown (Cragin, 1893)
SPECIMENS STUDIED & CONDITION: Isolated interambulacral plates only (Clark & Twitchell, 1915).
ETYMOLOGY: Likely named for "Dixie" (referring to the Southern United States or a local geographic feature near Dallas), as Cragin described it from Texas in 1893.
REMARKS & COMPARISONS
Remarks: This species is based on isolated plates. The non-crenulate, perforate tubercles suggest affinity with the subfamily Stereocidarinae (e.g., Stereocidaris or Temnocidaris), but the material is insufficient for definitive generic reassignment.
Comparisons: Cragin (1893) notes a resemblance to Cidaris serrifer Forbes in the facies of the interambulacra, but distinguishes C. dixiensis by the form of the plates.
Plate: CiDi-10
Series: Upper Cretaceous Group: Taylor Formation: Taylor Marl
Locale: Dallas County: Dallas Stage: Campanian
Length: 7 mm (plate) Width: 8 mm (plate)
Specimen in photo: old photos only
Repository: Cragin Collection (likely Non-vertebrate Paleo. Lab, Univ. of Texas)
HOLOTYPE INFO:
Holotype: Specimen from the Cragin Collection; presumably housed at the Non-vertebrate Paleontology Laboratory, University of Texas at Austin (Cragin, 1893; Adkins, 1928).
Locality: 9 miles northeast of Dallas, Dallas County, Texas (Cragin, 1893).
Horizon: Contact between the Austin Chalk and the Taylor Marl ("Ponderosa marl") (Cragin, 1893).
Systematic Paleontology
CLASS: ECHINOIDEA Leske, 1778
SUBCLASS: CIDAROIDEA Smith, 1984
ORDER: CIDAROIDA Claus, 1880
FAMILY: CIDARIDAE Gray, 1825
SUBFAMILY: STEREOCIDARINAE Lambert, 1900
GENUS: CIDARIS Leske, 1778
SPECIES: Cidaris dixiensis Cragin, 1893
TYPE SPECIES: Echinus cidaris Linnaeus, 1758
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Taylor (Cragin, 1893)
Formations: Taylor Marl (Clark & Twitchell, 1915)
Stratigraphic Units: Upper Cretaceous, Campanian (Cragin, 1893)
Counties: Dallas County (Cragin, 1893)
DESCRIPTION
TOP: Length, width: 7 mm L × 8 mm W (Interambulacral plate dimensions) (Cragin, 1893)
Top shape: Test rather small, thin (Cragin, 1893)
INTERAMB: Interamb plate shape: Plates described as isolated; size indicates form was likely not large (Clark & Twitchell, 1915)
Interamb granules: Ornamented with crowded, rounded granules; granules increase in size toward the areola (Cragin, 1893)
Granule arrangement: Largest granules form an alternating double row around the areola (Cragin, 1893)
TUBERCLES: Primary tubercles: Rather small and feebly elevated. Perforated. (Cragin, 1893)
Primary Crenulate: No (Cragin, 1893)
Primary Boss: Smooth; feebly elevated (Clark & Twitchell, 1915)
Primary Areola shape: Feebly depressed (Cragin, 1893)
Primary Mamelon: Small and perforated (Clark & Twitchell, 1915)
GRANULES: Granules pattern: Miliary space relatively narrow; covered with granules larger toward the areola (Clark & Twitchell, 1915)
SPINES: Shape: Unknown (Cragin, 1893)
SPECIMENS STUDIED & CONDITION: Isolated interambulacral plates only (Clark & Twitchell, 1915).
ETYMOLOGY: Likely named for "Dixie" (referring to the Southern United States or a local geographic feature near Dallas), as Cragin described it from Texas in 1893.
REMARKS & COMPARISONS
Remarks: This species is based on isolated plates. The non-crenulate, perforate tubercles suggest affinity with the subfamily Stereocidarinae (e.g., Stereocidaris or Temnocidaris), but the material is insufficient for definitive generic reassignment.
Comparisons: Cragin (1893) notes a resemblance to Cidaris serrifer Forbes in the facies of the interambulacra, but distinguishes C. dixiensis by the form of the plates.
