Miotoxaster wenoensis Thompson, 2020
Plate: MiWe-10
Series: Lower Cretaceous Group: Washita Formation: Weno
Locale: Sycamore Creek County: Tarrant Stage: Albian
Length: 23.0 MM Width: 20.7 mm Height: 13.6 mm
Collector: Dr. Stephen Crane
Specimen in Photo: NPL 94350
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 94350 .
Paratypes: NPL 94351 .
Locality: Sycamore Creek, Tarrant County, Texas.
Stratigraphy: Weno Formation, Washita Group.
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Atelostomata Zittel, 1879
Order: Spatangoida L. Agassiz, 1840
Family: Toxasteridae Lambert, 1920
Genus: MIOTOXASTER Pomel, 1883
Species: Miotoxaster wenoensis Thompson, 2020
TYPE SPECIES: Echinospatagus breyniusi d'Orbigny, 1854 (= Miotoxaster collegnii (Sismonda, 1844))
DIAGNOSIS
A small, oval Miotoxaster from the Albian of Texas. Distinguished by its tapered anterior end, lack of broad shoulders, and a periproct visible from the aboral view.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Weno Formation.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Tarrant.
Abundance: Three specimens found.
DESCRIPTION
TOP: Length, width, height: 23.0 mm L × 20.7 mm W × 13.6 mm H.
Top shape: Oval; widest posterior of center. Small anterior sulcus present.
Top domed: Top slanted.
SIDE: Ambitus: Positioned low, approximately 1/3 from the adoral surface.
Side shape: Posterior end truncated.
Profile: Apex is positioned posterior of center.
BOTTOM: Bottom shape: Flat.
AMB: Amb shape: Petals are slightly sunken and open-ended.
Amb arrangement: Anterior paired ambulacra are slightly flexed upward and are twice the length of the posterior pair. Posterior paired ambulacra are slightly flexed downward.
Unpaired Amb: Lanceolate, slightly sunken, and open-ended. Extends to the peristome.
PORE PAIRS: Shape: Slit-like in paired ambulacra.
Unpaired Amb: Differentiated with small pore pairs; pores are round, close together, and separated by a small bead.
TUBERCLES: Distribution: Scattered; concentrated on the peristome, near the ambitus, on the adoral surface, and at the anterior end.
GRANULES: (Not specified).
FASCIOLE: (Not specified).
APICAL SYSTEM: Type: Ethmophract.
Genital pores: Four gonopores.
PERIPROCT (ANUS): Shape: Oval; taller than wide (points vertically) with slightly pointed ends.
Location: High above the midpoint on the posterior truncation.
Visibility: Visible from above.
PERISTOME (MOUTH): Shape: Pentagonal; wider than tall.
Size: Small.
Orientation: Facing downward.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Three specimens studied. Holotype NPL 94350 and Paratypes NPL 94351 found in Tarrant County.
ETYMOLOGY
Named for the Weno Formation, the stratigraphic unit where the species is found.
REMARKS & COMPARISONS
Comparisons:
Plate: MiWe-10
Series: Lower Cretaceous Group: Washita Formation: Weno
Locale: Sycamore Creek County: Tarrant Stage: Albian
Length: 23.0 MM Width: 20.7 mm Height: 13.6 mm
Collector: Dr. Stephen Crane
Specimen in Photo: NPL 94350
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 94350 .
Paratypes: NPL 94351 .
Locality: Sycamore Creek, Tarrant County, Texas.
Stratigraphy: Weno Formation, Washita Group.
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Atelostomata Zittel, 1879
Order: Spatangoida L. Agassiz, 1840
Family: Toxasteridae Lambert, 1920
Genus: MIOTOXASTER Pomel, 1883
Species: Miotoxaster wenoensis Thompson, 2020
TYPE SPECIES: Echinospatagus breyniusi d'Orbigny, 1854 (= Miotoxaster collegnii (Sismonda, 1844))
DIAGNOSIS
A small, oval Miotoxaster from the Albian of Texas. Distinguished by its tapered anterior end, lack of broad shoulders, and a periproct visible from the aboral view.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Weno Formation.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Tarrant.
Abundance: Three specimens found.
DESCRIPTION
TOP: Length, width, height: 23.0 mm L × 20.7 mm W × 13.6 mm H.
Top shape: Oval; widest posterior of center. Small anterior sulcus present.
Top domed: Top slanted.
SIDE: Ambitus: Positioned low, approximately 1/3 from the adoral surface.
Side shape: Posterior end truncated.
Profile: Apex is positioned posterior of center.
BOTTOM: Bottom shape: Flat.
AMB: Amb shape: Petals are slightly sunken and open-ended.
Amb arrangement: Anterior paired ambulacra are slightly flexed upward and are twice the length of the posterior pair. Posterior paired ambulacra are slightly flexed downward.
Unpaired Amb: Lanceolate, slightly sunken, and open-ended. Extends to the peristome.
PORE PAIRS: Shape: Slit-like in paired ambulacra.
Unpaired Amb: Differentiated with small pore pairs; pores are round, close together, and separated by a small bead.
TUBERCLES: Distribution: Scattered; concentrated on the peristome, near the ambitus, on the adoral surface, and at the anterior end.
GRANULES: (Not specified).
FASCIOLE: (Not specified).
APICAL SYSTEM: Type: Ethmophract.
Genital pores: Four gonopores.
PERIPROCT (ANUS): Shape: Oval; taller than wide (points vertically) with slightly pointed ends.
Location: High above the midpoint on the posterior truncation.
Visibility: Visible from above.
PERISTOME (MOUTH): Shape: Pentagonal; wider than tall.
Size: Small.
Orientation: Facing downward.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Three specimens studied. Holotype NPL 94350 and Paratypes NPL 94351 found in Tarrant County.
ETYMOLOGY
Named for the Weno Formation, the stratigraphic unit where the species is found.
REMARKS & COMPARISONS
Comparisons:
- Pliotoxaster collegnii: Miotoxaster wenoensis is similar to the European P. collegnii (often classified as Miotoxaster collegnii) but differs by having a much smaller peristome, a very oval test with a tapered anterior end, and lacking broad shoulders.
