Washitaster bravoensis (Bose, 1910)
Plate: WaBr-10
Series: Lower Cretaceous Group: Washita Formation: Weno
Locale: Fort Worth County: Tarrant Stage: Albian
Length: 25.4 mm Width: 23.9 mm Height: 13.7 mm
Specimen in photos: BEG 34162 Hypotype
Collector: (Not specified)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: Instituto Geológico de México (IGM) Collection (Böse, 1910).
Locality: Cerro de Muleros, Chihuahua/New Mexico Border.
Stratigraphy: Subdivision 6 (Equivalent to Weno/Pawpaw Formations).
SYNONYMY
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: WASHITASTER Lambert, 1927
Species: Washitaster bravoensis (Böse, 1910)
TYPE SPECIES: Hemiaster riovistae Adkins, 1920 (Type of Genus)
DIAGNOSIS
A small (approx. 1 inch) Washitaster with broadly rounded sides and a tapering, truncated posterior end. The widest point is anterior to the apical system, while the tallest point is posterior. Distinguished from Heteraster (Enallaster) by the presence of a peripetalous fasciole (often multiple bands) crossing the anterior ambulacrum.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Weno Formation; Pawpaw Formation; Main Street Limestone; Grayson Marl.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Tarrant, Grayson, Pecos, El Paso.
Abundance: Occasional to locally abundant in the Upper Washita (Weno/Pawpaw).
DESCRIPTION
TOP: Length, width, height: 25.4 mm L × 23.9 mm W × 13.7 mm H. Top shape: Cordate; broadly rounded sides. Widest point is in front of the apical system (about 2/5 the length from the anterior end). Top domed: Apex (tallest point) is behind the apical system, about three-fourths the way back (Adkins & Winton, 1919).
SIDE: Side shape: Lower and less inflated than H. texanus and H. mexicanus. Posterior end tapers and is truncated. Profile: Anterior slope is variable; generally slopes forward from the apical system.
BOTTOM: Bottom shape: Adoral surface is slightly convex.
AMB: Amb shape: Unpaired anterior ambulacrum (III) is sunken. Paired petals are short, spreading, and flexuous. Amb arrangement: Posterolaterals are short.
PORE PAIRS: Unpaired Amb: Heterogeneous (Enallaster-type); alternating pairs of round and slit-like pores. Paired Ambs: Elongated (slit-like) in the posterior zones; smaller in the anterior zones.
TUBERCLES: Distribution: Small and scattered.
GRANULES: Distribution: Dense granulation.
FASCIOLE: Peripetalous: Present (Diagnostic of Washitaster).
APICAL SYSTEM: Location: Nearly central.
PERIPROCT (ANUS): Shape: Oval. Location: High on the posterior truncation.
PERISTOME (MOUTH): Shape: Subpentagonal to reniform. Location: Anterior.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Hypotype BEG 34162.
ETYMOLOGY
Named for the Rio Bravo (Rio Grande), near the type locality at Cerro de Muleros.
REMARKS & COMPARISONS
Remarks: Lambert (1927) established the genus Washitaster based on the presence of a fasciole, distinct from Heteraster (Enallaster). While Cooke (1955) synonymized W. bravoensis with W. riovistae, this description retains W. bravoensis as a distinct and valid species, noting its specific occurrence in the Upper Washita (Weno/Pawpaw).
Comparisons:
Plate: WaBr-10
Series: Lower Cretaceous Group: Washita Formation: Weno
Locale: Fort Worth County: Tarrant Stage: Albian
Length: 25.4 mm Width: 23.9 mm Height: 13.7 mm
Specimen in photos: BEG 34162 Hypotype
Collector: (Not specified)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: Instituto Geológico de México (IGM) Collection (Böse, 1910).
Locality: Cerro de Muleros, Chihuahua/New Mexico Border.
Stratigraphy: Subdivision 6 (Equivalent to Weno/Pawpaw Formations).
SYNONYMY
- Enallaster bravoensis Böse, 1910
- Enallaster (Washitaster) bravoensis (Böse) Cooke, 1955
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: WASHITASTER Lambert, 1927
Species: Washitaster bravoensis (Böse, 1910)
TYPE SPECIES: Hemiaster riovistae Adkins, 1920 (Type of Genus)
DIAGNOSIS
A small (approx. 1 inch) Washitaster with broadly rounded sides and a tapering, truncated posterior end. The widest point is anterior to the apical system, while the tallest point is posterior. Distinguished from Heteraster (Enallaster) by the presence of a peripetalous fasciole (often multiple bands) crossing the anterior ambulacrum.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Weno Formation; Pawpaw Formation; Main Street Limestone; Grayson Marl.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Tarrant, Grayson, Pecos, El Paso.
Abundance: Occasional to locally abundant in the Upper Washita (Weno/Pawpaw).
DESCRIPTION
TOP: Length, width, height: 25.4 mm L × 23.9 mm W × 13.7 mm H. Top shape: Cordate; broadly rounded sides. Widest point is in front of the apical system (about 2/5 the length from the anterior end). Top domed: Apex (tallest point) is behind the apical system, about three-fourths the way back (Adkins & Winton, 1919).
SIDE: Side shape: Lower and less inflated than H. texanus and H. mexicanus. Posterior end tapers and is truncated. Profile: Anterior slope is variable; generally slopes forward from the apical system.
BOTTOM: Bottom shape: Adoral surface is slightly convex.
AMB: Amb shape: Unpaired anterior ambulacrum (III) is sunken. Paired petals are short, spreading, and flexuous. Amb arrangement: Posterolaterals are short.
PORE PAIRS: Unpaired Amb: Heterogeneous (Enallaster-type); alternating pairs of round and slit-like pores. Paired Ambs: Elongated (slit-like) in the posterior zones; smaller in the anterior zones.
TUBERCLES: Distribution: Small and scattered.
GRANULES: Distribution: Dense granulation.
FASCIOLE: Peripetalous: Present (Diagnostic of Washitaster).
APICAL SYSTEM: Location: Nearly central.
PERIPROCT (ANUS): Shape: Oval. Location: High on the posterior truncation.
PERISTOME (MOUTH): Shape: Subpentagonal to reniform. Location: Anterior.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Hypotype BEG 34162.
ETYMOLOGY
Named for the Rio Bravo (Rio Grande), near the type locality at Cerro de Muleros.
REMARKS & COMPARISONS
Remarks: Lambert (1927) established the genus Washitaster based on the presence of a fasciole, distinct from Heteraster (Enallaster). While Cooke (1955) synonymized W. bravoensis with W. riovistae, this description retains W. bravoensis as a distinct and valid species, noting its specific occurrence in the Upper Washita (Weno/Pawpaw).
Comparisons:
- Heteraster mexicanus (Enallaster texanus auct.): W. bravoensis is lower, less inflated, and more narrowed/truncated posteriorly than H. mexicanus (Adkins & Winton, 1919).
- Heteraster obliquatus: W. bravoensis is taller posteriorly and relatively more elongated than H. obliquatus.
