Washitaster inflatus (Cragin, 1893)
Plate: WaIn-10
Series: Lower Cretaceous Group: Washita Formation: Grayson
Locale: Burleson County: Johnson Stage: Albian
Length: 31 mm Width: 29 mm Height: 23 mm
Specimen in photos: NPL 94330
Collector: (Not specified)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: Originally collected by Mr. Wooldridge (Cragin, 1893). Repository likely UT (BEG) or USNM.
Locality: Denton Creek, 1 mile east of Roanoke, Denton County, Texas; and Choctaw Creek, east of Denison, Grayson County, Texas.
Stratigraphy: "Arietina marl" (= Grayson Formation / Del Rio Clay), Washita Group.
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 inflatus (Cragin, 1893)
TYPE SPECIES: Hemiaster riovistae Adkins, 1920 (= Washitaster bravoensis)
DIAGNOSIS
A small, subglobose Washitaster distinguished by its high, inflated profile (anterior and posterior equally inflated). The unpaired ambulacrum features a pore alternation of one contracted and two (or three) extended pairs. Narrow branching peripetalous fascioles are present (Cooke, 1955).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Grayson Formation (Arietina marl).
Stratigraphic Units: Lower Cretaceous, Albian (Uppermost).
Counties: Johnson, Denton, Grayson.
Abundance: Rare.
DESCRIPTION
TOP: Length, width, height: 31.0 mm L × 29.0 mm W × 23.0 mm H. Top shape: Subglobose; weakly emarginate in front, weakly truncated behind. Top domed: Upper surface more strongly inflated than the lower (Cooke, 1955).
SIDE: Side shape: Relatively much higher than Heteraster texanus; posterior part is nearly as high as the anterior (Cragin, 1893). Profile: Inflated.
BOTTOM: Bottom shape: Lower surface slightly convex.
AMB: Amb shape: Anterior paired petals slightly depressed, slightly flexuous, diverging at ~90°. Posterior petals flush, straight, and nearly half as long as the anterior pair; diverging at ~90°. Unpaired Amb: Contains irregularly alternating pairs of long and short pores.
PORE PAIRS: Arrangement: Unpaired ambulacrum: one contracted (short) pore pair alternating with two (or sometimes three) extended (long) pairs. Short pores are divided by a flattened bead. Paired Ambs: Pores conjugate; anterior zone narrow, posterior zone wider (Cooke, 1955).
TUBERCLES: Distribution: Rather small; largest on the anterior half.
GRANULES: (Not specified).
FASCIOLE: Peripetalous: Narrow branching peripetalous fascioles are present (Cooke, 1955).
APICAL SYSTEM: Location: Slightly posterior. Genital pores: Four genital plates; posterior pair nearly separated by the madreporite (Cooke, 1955).
PERIPROCT (ANUS): Shape: Nearly round (Cooke, 1955); somewhat narrower than in H. texanus (Cragin, 1893). Location: At the top of a weak posterior truncation.
PERISTOME (MOUTH): Shape: Nearly round. Location: At the anterior third.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Figured Specimen NPL 94330.
ETYMOLOGY
From the Latin inflatus (swollen/puffed), referring to the high, subglobose profile of the test.
REMARKS & COMPARISONS
Remarks: Cooke (1955) noted that W. inflatus is likely a valid species, distinct from W. bravoensis by being "more obese." The presence of fascioles (noted by Cooke) confirms the assignment to Washitaster rather than Heteraster (Enallaster).
Comparisons:
Plate: WaIn-10
Series: Lower Cretaceous Group: Washita Formation: Grayson
Locale: Burleson County: Johnson Stage: Albian
Length: 31 mm Width: 29 mm Height: 23 mm
Specimen in photos: NPL 94330
Collector: (Not specified)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: Originally collected by Mr. Wooldridge (Cragin, 1893). Repository likely UT (BEG) or USNM.
Locality: Denton Creek, 1 mile east of Roanoke, Denton County, Texas; and Choctaw Creek, east of Denison, Grayson County, Texas.
Stratigraphy: "Arietina marl" (= Grayson Formation / Del Rio Clay), Washita Group.
SYNONYMY
- Enallaster inflatus Cragin, 1893
- Enallaster (Washitaster) inflatus (Cragin) 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 inflatus (Cragin, 1893)
TYPE SPECIES: Hemiaster riovistae Adkins, 1920 (= Washitaster bravoensis)
DIAGNOSIS
A small, subglobose Washitaster distinguished by its high, inflated profile (anterior and posterior equally inflated). The unpaired ambulacrum features a pore alternation of one contracted and two (or three) extended pairs. Narrow branching peripetalous fascioles are present (Cooke, 1955).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Grayson Formation (Arietina marl).
Stratigraphic Units: Lower Cretaceous, Albian (Uppermost).
Counties: Johnson, Denton, Grayson.
Abundance: Rare.
DESCRIPTION
TOP: Length, width, height: 31.0 mm L × 29.0 mm W × 23.0 mm H. Top shape: Subglobose; weakly emarginate in front, weakly truncated behind. Top domed: Upper surface more strongly inflated than the lower (Cooke, 1955).
SIDE: Side shape: Relatively much higher than Heteraster texanus; posterior part is nearly as high as the anterior (Cragin, 1893). Profile: Inflated.
BOTTOM: Bottom shape: Lower surface slightly convex.
AMB: Amb shape: Anterior paired petals slightly depressed, slightly flexuous, diverging at ~90°. Posterior petals flush, straight, and nearly half as long as the anterior pair; diverging at ~90°. Unpaired Amb: Contains irregularly alternating pairs of long and short pores.
PORE PAIRS: Arrangement: Unpaired ambulacrum: one contracted (short) pore pair alternating with two (or sometimes three) extended (long) pairs. Short pores are divided by a flattened bead. Paired Ambs: Pores conjugate; anterior zone narrow, posterior zone wider (Cooke, 1955).
TUBERCLES: Distribution: Rather small; largest on the anterior half.
GRANULES: (Not specified).
FASCIOLE: Peripetalous: Narrow branching peripetalous fascioles are present (Cooke, 1955).
APICAL SYSTEM: Location: Slightly posterior. Genital pores: Four genital plates; posterior pair nearly separated by the madreporite (Cooke, 1955).
PERIPROCT (ANUS): Shape: Nearly round (Cooke, 1955); somewhat narrower than in H. texanus (Cragin, 1893). Location: At the top of a weak posterior truncation.
PERISTOME (MOUTH): Shape: Nearly round. Location: At the anterior third.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Figured Specimen NPL 94330.
ETYMOLOGY
From the Latin inflatus (swollen/puffed), referring to the high, subglobose profile of the test.
REMARKS & COMPARISONS
Remarks: Cooke (1955) noted that W. inflatus is likely a valid species, distinct from W. bravoensis by being "more obese." The presence of fascioles (noted by Cooke) confirms the assignment to Washitaster rather than Heteraster (Enallaster).
Comparisons:
- Heteraster texanus: W. inflatus is much higher, particularly in the posterior region (which is depressed/declivous in texanus), and has a narrower periproct (Cragin, 1893).
- Washitaster bravoensis: W. inflatus is similar but significantly more obese/inflated.
