Prionocidaris anacachoensis Thompson, 2016
Plate: PrAn-10
Series: Upper Cretaceous Group: Taylor Formation: Anacacho
Locale: Sabinal County: Uvalde Stage:Campanian
Width: 26.6 mm (test)
Specimen in photo: NPL 83046 Holotype
Collector: Stephen Crane
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 83046.
Locality: Sabinal, Uvalde County, Texas.
Stratigraphy: Anacacho Formation, Taylor Group.
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Cidaroidea Smith, 1984
Order: Cidaroida Claus, 1880
Family: Cidaridae Gray, 1825
Genus: PRIONOCIDARIS A. Agassiz, 1863
Species: Prionocidaris anacachoensis Thompson, 2016
TYPE SPECIES: Cidarites pistillaris Lamarck, 1816
DIAGNOSIS
A Prionocidaris from the Upper Cretaceous of Texas characterized by slightly oval areolas and reduced granulation compared to congeners. Primary spines possess a distinct naked section above the neck.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Taylor
Formations: Anacacho Formation.
Stratigraphic Units: Upper Cretaceous, Campanian.
Counties: Uvalde.
Abundance: Rare; only two specimens known from one location.
DESCRIPTION
TOP: Length/Width: 26.6 mm diameter. Top shape: Round.
SIDE: Side shape: Tall and inflated. Ambitus: Positioned at midpoint.
BOTTOM: Bottom shape: Flat.
AMB: Amb shape: Slightly wavy. Amb arrangement: Perradial zone is filled with two rows of marginal tubercles and two inner rows of granules between them.
PORE PAIRS: Arrangement: Conjugate; widely separated with a groove between.
TUBERCLES: Primary Perforated: Yes. Primary Crenulate: No (Non-crenulate). Interambulacral Tubercles: Large at ambitus, reducing in size toward the apical system and peristome. Bosses are incised. Areolas: Slightly oval. Scrobicular Tubercles: Slightly differentiated.
GRANULES: Distribution: Dense granulation along the adradial suture. Granulation is absent vertically between primary tubercles (areolas likely confluent or nearly so).
FASCIOLE: Absent in Cidaroida.
INTERAMB: Width: Over 4 times the width of ambulacra at the ambitus. Arrangement: Two rows of primary tubercles.
APICAL SYSTEM: Condition: Not visible in holotype.
PERIPROCT (ANUS): Condition: Not visible.
PERISTOME (MOUTH): Size: Diameter 46% of the width of the test.
SPINES: Primary Spines: Very long, slender, and tapered with longitudinal striations; distinctive naked section present above the neck. Secondary Spines: Lanceolate, flattened, and smooth. Ambulacral Spines: Flattened and thin (about 2.3 times less wide than secondaries).
SPECIMENS STUDIED & CONDITION: Holotype NPL 83046. Collected by Stephen Crane.
ETYMOLOGY
Named after the Anacacho Formation, the stratigraphic unit where the holotype was found.
REMARKS & COMPARISONS
Remarks: This species is assigned to Prionocidaris based on the non-crenulate tubercles, conjugate pores, and spine morphology.
Comparisons:
Plate: PrAn-10
Series: Upper Cretaceous Group: Taylor Formation: Anacacho
Locale: Sabinal County: Uvalde Stage:Campanian
Width: 26.6 mm (test)
Specimen in photo: NPL 83046 Holotype
Collector: Stephen Crane
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 83046.
Locality: Sabinal, Uvalde County, Texas.
Stratigraphy: Anacacho Formation, Taylor Group.
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Cidaroidea Smith, 1984
Order: Cidaroida Claus, 1880
Family: Cidaridae Gray, 1825
Genus: PRIONOCIDARIS A. Agassiz, 1863
Species: Prionocidaris anacachoensis Thompson, 2016
TYPE SPECIES: Cidarites pistillaris Lamarck, 1816
DIAGNOSIS
A Prionocidaris from the Upper Cretaceous of Texas characterized by slightly oval areolas and reduced granulation compared to congeners. Primary spines possess a distinct naked section above the neck.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Taylor
Formations: Anacacho Formation.
Stratigraphic Units: Upper Cretaceous, Campanian.
Counties: Uvalde.
Abundance: Rare; only two specimens known from one location.
DESCRIPTION
TOP: Length/Width: 26.6 mm diameter. Top shape: Round.
SIDE: Side shape: Tall and inflated. Ambitus: Positioned at midpoint.
BOTTOM: Bottom shape: Flat.
AMB: Amb shape: Slightly wavy. Amb arrangement: Perradial zone is filled with two rows of marginal tubercles and two inner rows of granules between them.
PORE PAIRS: Arrangement: Conjugate; widely separated with a groove between.
TUBERCLES: Primary Perforated: Yes. Primary Crenulate: No (Non-crenulate). Interambulacral Tubercles: Large at ambitus, reducing in size toward the apical system and peristome. Bosses are incised. Areolas: Slightly oval. Scrobicular Tubercles: Slightly differentiated.
GRANULES: Distribution: Dense granulation along the adradial suture. Granulation is absent vertically between primary tubercles (areolas likely confluent or nearly so).
FASCIOLE: Absent in Cidaroida.
INTERAMB: Width: Over 4 times the width of ambulacra at the ambitus. Arrangement: Two rows of primary tubercles.
APICAL SYSTEM: Condition: Not visible in holotype.
PERIPROCT (ANUS): Condition: Not visible.
PERISTOME (MOUTH): Size: Diameter 46% of the width of the test.
SPINES: Primary Spines: Very long, slender, and tapered with longitudinal striations; distinctive naked section present above the neck. Secondary Spines: Lanceolate, flattened, and smooth. Ambulacral Spines: Flattened and thin (about 2.3 times less wide than secondaries).
SPECIMENS STUDIED & CONDITION: Holotype NPL 83046. Collected by Stephen Crane.
ETYMOLOGY
Named after the Anacacho Formation, the stratigraphic unit where the holotype was found.
REMARKS & COMPARISONS
Remarks: This species is assigned to Prionocidaris based on the non-crenulate tubercles, conjugate pores, and spine morphology.
Comparisons:
- Prionocidaris vendocinensis: P. anacachoensis differs by having less test height, less granulation, and greater variance in the size of the primary interambulacral tubercles.
- Prionocidaris granulostriata: P. anacachoensis has significantly less granulation.
- Prionocidaris pistillaris: The spines of the type species lack the naked area above the neck found in P. anacachoensis.
