Coenholectypus wenoensis Thompson, 2020
Plate: CoWe-10
Series: Lower Cretaceous Group: Washita Formation: Weno and Pawpaw
Locale: Fort Worth County: Tarrant Stage: Albian
Length: 44.8 mm Height: 23.1 mm
Collection: William Thompson
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 94311 — Non-vertebrate Paleontology Laboratory, University of Texas
Paratype: NPL 94312
Locality: Fort Worth, Tarrant County, Texas
Systematic Paleontology
CLASS: ECHINOIDEA Leske, 1778
SUBCLASS: EUECHINOIDEA Bronn, 1860
INFRACLASS: IRREGULARIA Latreille, 1825
SUPERORDER: GNATHOSTOMATA Zittel, 1879
ORDER: HOLECTYPOIDA Duncan, 1889
FAMILY: COENHOLECTYPIDAE Smith & Wright, 1999
GENUS: COENHOLECTYPUS Pomel, 1883
SPECIES: Coenholectypus wenoensis Thompson, 2020
TYPE SPECIES: Discoidea depressa L. Agassiz, 1839
DIAGNOSIS
Small to large Coenholectypus from the Weno and Pawpaw Formations of the Washita Group with a large periproct that does not cut into the margin .
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Weno Formation, Pawpaw Formation
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Tarrant (Fort Worth), Johnson (Rio Vista)
Matrix: Found in loose gray marl and large, hard, yellowish boulders
DESCRIPTION
TOP: Length, height: 44.8 mm L × 23.1 mm H
Top shape: Round, only slightly pentagonal from above
Top domed: Inflated, domed
SIDE: Ambitus: 1/5th from the adoral side; slight point at ambitus
Side shape: Inflated
BOTTOM: Bottom flat: Flat
SIZE: Range: 15.5 mm to 44.8 mm Length
AMB: Amb shape: Lanceolate, very pointed; straight to ambitus
Amb width: Widest at ambitus; adorally begins to narrow
Amb arrangement: Plating unigeminate
INTERAMB: Interamb width: Slightly less than three times size of ambulacra at ambitus
Interamb plating: Compound plates, much wider than tall; suture plating distinct
PORE PAIRS: Shape: Small, narrow
Arrangement: Uniserial, oblique; more spaced adorally
TUBERCLES: Primary tubercles:
Ambulacra: Small, perforated, crenulated; rows irregular. Primary tubercle on every third plate; sparse above ambitus .
Interambulacra: Many primary tubercles on each compound plate; appear irregular. Crenulate and perforate .
Secondary tubercles: Concentrated below ambitus in ambulacra; somewhat irregular .
Granules: Many granules on interambulacral plates .
APICAL SYSTEM: Size / Location: Central, small
Plates: Genitals pentagonal; 5 gonopores
Madreporite: Large
PERIPROCT (ANUS): Shape & Size: Teardrop shaped; pointed on both ends but slightly less away from center; width 57% of length
Location: Infra-marginal (on bottom); closer to peristome than to margin
Visibility: Does not cut into the margin; cannot be seen from above or side
PERISTOME (MOUTH): Size: 25% of diameter of test
Shape: Round, slight oval tendency
Lip: Notches small
SPECIMENS STUDIED & CONDITION
Specimen condition: Two specimens studied (one very large, one very small). Holotype NPL 94311.
ETYMOLOGY: Named for the Weno formation.
REMARKS & COMPARISONS
Remarks: The placement of the large periproct on the bottom and its pointed ends separate this from other Coenholectypus. The slightly pointed dome is much like that of Coenholectypus engerrandi .
Plate: CoWe-10
Series: Lower Cretaceous Group: Washita Formation: Weno and Pawpaw
Locale: Fort Worth County: Tarrant Stage: Albian
Length: 44.8 mm Height: 23.1 mm
Collection: William Thompson
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 94311 — Non-vertebrate Paleontology Laboratory, University of Texas
Paratype: NPL 94312
Locality: Fort Worth, Tarrant County, Texas
Systematic Paleontology
CLASS: ECHINOIDEA Leske, 1778
SUBCLASS: EUECHINOIDEA Bronn, 1860
INFRACLASS: IRREGULARIA Latreille, 1825
SUPERORDER: GNATHOSTOMATA Zittel, 1879
ORDER: HOLECTYPOIDA Duncan, 1889
FAMILY: COENHOLECTYPIDAE Smith & Wright, 1999
GENUS: COENHOLECTYPUS Pomel, 1883
SPECIES: Coenholectypus wenoensis Thompson, 2020
TYPE SPECIES: Discoidea depressa L. Agassiz, 1839
DIAGNOSIS
Small to large Coenholectypus from the Weno and Pawpaw Formations of the Washita Group with a large periproct that does not cut into the margin .
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Weno Formation, Pawpaw Formation
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Tarrant (Fort Worth), Johnson (Rio Vista)
Matrix: Found in loose gray marl and large, hard, yellowish boulders
DESCRIPTION
TOP: Length, height: 44.8 mm L × 23.1 mm H
Top shape: Round, only slightly pentagonal from above
Top domed: Inflated, domed
SIDE: Ambitus: 1/5th from the adoral side; slight point at ambitus
Side shape: Inflated
BOTTOM: Bottom flat: Flat
SIZE: Range: 15.5 mm to 44.8 mm Length
AMB: Amb shape: Lanceolate, very pointed; straight to ambitus
Amb width: Widest at ambitus; adorally begins to narrow
Amb arrangement: Plating unigeminate
INTERAMB: Interamb width: Slightly less than three times size of ambulacra at ambitus
Interamb plating: Compound plates, much wider than tall; suture plating distinct
PORE PAIRS: Shape: Small, narrow
Arrangement: Uniserial, oblique; more spaced adorally
TUBERCLES: Primary tubercles:
Ambulacra: Small, perforated, crenulated; rows irregular. Primary tubercle on every third plate; sparse above ambitus .
Interambulacra: Many primary tubercles on each compound plate; appear irregular. Crenulate and perforate .
Secondary tubercles: Concentrated below ambitus in ambulacra; somewhat irregular .
Granules: Many granules on interambulacral plates .
APICAL SYSTEM: Size / Location: Central, small
Plates: Genitals pentagonal; 5 gonopores
Madreporite: Large
PERIPROCT (ANUS): Shape & Size: Teardrop shaped; pointed on both ends but slightly less away from center; width 57% of length
Location: Infra-marginal (on bottom); closer to peristome than to margin
Visibility: Does not cut into the margin; cannot be seen from above or side
PERISTOME (MOUTH): Size: 25% of diameter of test
Shape: Round, slight oval tendency
Lip: Notches small
SPECIMENS STUDIED & CONDITION
Specimen condition: Two specimens studied (one very large, one very small). Holotype NPL 94311.
ETYMOLOGY: Named for the Weno formation.
REMARKS & COMPARISONS
Remarks: The placement of the large periproct on the bottom and its pointed ends separate this from other Coenholectypus. The slightly pointed dome is much like that of Coenholectypus engerrandi .
