Pedinopsis molineuxae Thompson, 2016
Plate: PeMo-10
Series: Lower Cretaceous Group: Washita Formation: Weno
Locale: Cleburne County: Johnson Stage: Albian
Length: 61.5 mm Height: 48.6 mm
Specimen in photo: NPL 73953 Holotype
Collector: William R. Thompson, Jr.
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 73953 .
Locality: South of Cleburne, Johnson County, Texas.
Stratigraphy: Weno Formation, Washita Group.
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Calycina Gregory, 1900
Order: Phymosomatoida Mortensen, 1904
Family: Pedinopsidae Durham, 1955
Genus: PEDINOPSIS Cotteau, 1863
Species: Pedinopsis molineuxae Thompson, 2016
TYPE SPECIES: Pedinopsis meridanensis Cotteau, 1863
DIAGNOSIS
A large Pedinopsis from the Albian of Texas characterized by adapical ambulacral plating composed of 6 elements (sexigeminate). Pore pairs are biserial adapically and uniserial adorally. The peristome is proportionally smaller than in P. meridanensis.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Weno Formation.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Johnson.
Abundance: Rare; only three specimens known.
DESCRIPTION
TOP: Length, width, height: 61.5 mm L × 48.6 mm H. Top shape: Round; slightly pentagonal with ambulacra very slightly raised. Top domed: Domed above; subglobular.
SIDE: Ambitus: Positioned 40% of height from the adoral surface. Side shape: Rounded; more rounded than P. pondi.
BOTTOM: Bottom shape: Flat.
AMB: Amb shape: Lanceolate, pointed at apical system, widest at ambitus, narrowing again at peristome. Amb arrangement: Perradius is naked for the top third of the ambulacra. Width: Interambulacra are more than twice the width of ambulacra at the ambitus. Plating: Adapical plating composed of 6 sets of pore pairs (sexigeminate); ambitus plating composed of 4 to 5 pore pairs; peristome plating composed of 3 sets (trigeminate).
PORE PAIRS: Arrangement: Biserial adapically; uniserial adorally. Shape: Round.
TUBERCLES: Primary Perforated: Yes. Primary Crenulate: Yes. Mamelons: Small. Ambulacral Tubercles: One primary tubercle on each plate located at the margin adjacent to pore pairs. Secondary tubercles (some equal in size to primaries) run from the ambitus down to near the peristome. Interambulacral Tubercles: One primary tubercle on each plate from apical system to peristome. Below ambitus, secondary tubercles cover the interambulacra (up to 6 wide), most nearly equal in size to primaries; numbers reduce approaching the peristome (from 6 to 1).
GRANULES: Distribution: In ambulacra: Granulation extends to peristome where secondaries end adorally, and to apical system where secondaries end aborally. In interambulacra: Smaller secondary tubercles and granules run in partially aligned rows toward the apical system above the ambitus. Granulation fills in the rest of each interambulacrum below the ambitus.
FASCIOLE: Absent.
INTERAMB: Width: Plates are 5 times wider than tall at the ambitus; plates are taller than ambulacral plates. Features: Interradius naked at midpoint and above.
APICAL SYSTEM: Location: Central. Size: Small; measuring 9.3 mm (approx 15% of length). Condition: Plating missing in holotype.
PERIPROCT (ANUS): Condition: Missing.
PERISTOME (MOUTH): Size: Diameter 18.3 mm (33% of test diameter). Shape: Slightly depressed. Lip: Notches small with slightly thickened lips.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Holotype NPL 73953 and two other specimens in the Frank Crane Collection.
ETYMOLOGY
Named after Ann Molineux, Curator and Collection Manager of Non-vertebrate Paleontology at the Jackson School of Geosciences, University of Texas at Austin, in recognition of her contributions and assistance.
REMARKS & COMPARISONS
Remarks: Pedinopsis molineuxae morphologically resembles Echinopsis lineatus, but E. lineatus has uniserial pores throughout, whereas P. molineuxae is biserial aborally and uniserial adorally.
Comparisons:
Plate: PeMo-10
Series: Lower Cretaceous Group: Washita Formation: Weno
Locale: Cleburne County: Johnson Stage: Albian
Length: 61.5 mm Height: 48.6 mm
Specimen in photo: NPL 73953 Holotype
Collector: William R. Thompson, Jr.
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 73953 .
Locality: South of Cleburne, Johnson County, Texas.
Stratigraphy: Weno Formation, Washita Group.
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Calycina Gregory, 1900
Order: Phymosomatoida Mortensen, 1904
Family: Pedinopsidae Durham, 1955
Genus: PEDINOPSIS Cotteau, 1863
Species: Pedinopsis molineuxae Thompson, 2016
TYPE SPECIES: Pedinopsis meridanensis Cotteau, 1863
DIAGNOSIS
A large Pedinopsis from the Albian of Texas characterized by adapical ambulacral plating composed of 6 elements (sexigeminate). Pore pairs are biserial adapically and uniserial adorally. The peristome is proportionally smaller than in P. meridanensis.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Weno Formation.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Johnson.
Abundance: Rare; only three specimens known.
DESCRIPTION
TOP: Length, width, height: 61.5 mm L × 48.6 mm H. Top shape: Round; slightly pentagonal with ambulacra very slightly raised. Top domed: Domed above; subglobular.
SIDE: Ambitus: Positioned 40% of height from the adoral surface. Side shape: Rounded; more rounded than P. pondi.
BOTTOM: Bottom shape: Flat.
AMB: Amb shape: Lanceolate, pointed at apical system, widest at ambitus, narrowing again at peristome. Amb arrangement: Perradius is naked for the top third of the ambulacra. Width: Interambulacra are more than twice the width of ambulacra at the ambitus. Plating: Adapical plating composed of 6 sets of pore pairs (sexigeminate); ambitus plating composed of 4 to 5 pore pairs; peristome plating composed of 3 sets (trigeminate).
PORE PAIRS: Arrangement: Biserial adapically; uniserial adorally. Shape: Round.
TUBERCLES: Primary Perforated: Yes. Primary Crenulate: Yes. Mamelons: Small. Ambulacral Tubercles: One primary tubercle on each plate located at the margin adjacent to pore pairs. Secondary tubercles (some equal in size to primaries) run from the ambitus down to near the peristome. Interambulacral Tubercles: One primary tubercle on each plate from apical system to peristome. Below ambitus, secondary tubercles cover the interambulacra (up to 6 wide), most nearly equal in size to primaries; numbers reduce approaching the peristome (from 6 to 1).
GRANULES: Distribution: In ambulacra: Granulation extends to peristome where secondaries end adorally, and to apical system where secondaries end aborally. In interambulacra: Smaller secondary tubercles and granules run in partially aligned rows toward the apical system above the ambitus. Granulation fills in the rest of each interambulacrum below the ambitus.
FASCIOLE: Absent.
INTERAMB: Width: Plates are 5 times wider than tall at the ambitus; plates are taller than ambulacral plates. Features: Interradius naked at midpoint and above.
APICAL SYSTEM: Location: Central. Size: Small; measuring 9.3 mm (approx 15% of length). Condition: Plating missing in holotype.
PERIPROCT (ANUS): Condition: Missing.
PERISTOME (MOUTH): Size: Diameter 18.3 mm (33% of test diameter). Shape: Slightly depressed. Lip: Notches small with slightly thickened lips.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Holotype NPL 73953 and two other specimens in the Frank Crane Collection.
ETYMOLOGY
Named after Ann Molineux, Curator and Collection Manager of Non-vertebrate Paleontology at the Jackson School of Geosciences, University of Texas at Austin, in recognition of her contributions and assistance.
REMARKS & COMPARISONS
Remarks: Pedinopsis molineuxae morphologically resembles Echinopsis lineatus, but E. lineatus has uniserial pores throughout, whereas P. molineuxae is biserial aborally and uniserial adorally.
Comparisons:
- Pedinopsis pondi: P. molineuxae is more pentagonal (vs. melon-shaped with bulging interambs in pondi). In lateral view, P. molineuxae is more rounded (vs. pointed in pondi). The primary tubercles above the adoral surface are much larger in P. molineuxae. The peristome is proportionally larger in P. molineuxae.
- Dumblea symmetrica: Differs from the smaller D. symmetrica, which has only 3 pore pair sets per plate (trigeminate) and is biserial throughout. D. symmetrica has thick granulation at the perradius and interradius near the apical system, whereas P. molineuxae is naked in both areas. Tubercles are larger on P. molineuxae.
- Pedinopsis meridanensis: P. molineuxae has a smaller peristome with less pronounced lips and more pronounced primary tubercles.
