Heteraster texanus (Roemer, 1852)
Plate: HeTe-10
Series: Lower Cretaceous Group: Fredericksburg Formation: Walnut
Locale: Harker Heights County: Bell Stage: Albian
Length: 27.1 mm Width: 23.9 mm Height: 16.2 mm
Specimen in photo: Collection of Ed Elliott
HOLOTYPE INFO:
Holotype: Described by Roemer (1852). Types likely housed at the Roemer Museum (Hildesheim) or University of Bonn, Germany.
Locality: Fredericksburg, Texas (Roemer, 1852)
Stratigraphy: Fredericksburg Group (Roemer, 1852)
SYNONYMY
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: HETERASTER d'Orbigny, 1853
Species: Heteraster texanus (Roemer, 1852)
TYPE SPECIES: Spatangus oblongus Brongniart, 1821
DIAGNOSIS
Test oblong, cordiform, broad in anterior portion, contracted and truncated posteriorly, with deep anterior groove. Upper surface convex, elevated; base flat, depressed at the peristome. Ambulacra narrow and unequal; posterolateral pair much shorter than others. Apical system small and compact. Periproct situated high above the margin (Clark & Twitchell, 1915).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg
Formations: Walnut Formation (Specimen); Fredericksburg, and Washita Groups (Clark & Twitchell, 1915)
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Bell County (Specimen)
DESCRIPTION
TOP: Length, width, height: 27.1 mm L × 23.9 mm W × 16.2 mm H
Top shape: Oblong, cordiform; broad in anterior portion, contracted posteriorly (Clark & Twitchell, 1915).
Top domed: Convex, elevated (Clark & Twitchell, 1915).
Sulcus: Well-defined anterior groove; narrow and slightly depressed at its head (Clark & Twitchell, 1915).
SIDE: Side shape: Rounded and inflated; posterior face truncated to the margin (Clark & Twitchell, 1915).
BOTTOM: Bottom flat: Base flat, except for peristomal depression and a central elevated region extending to the posterior border (Clark & Twitchell, 1915).
AMB: Amb arrangement: Very unequal (Clark & Twitchell, 1915).
Unpaired (III): Situated in anterior groove; wider than other areas (Clark & Twitchell, 1915).
Anterolateral (II & IV): Large; curved backward in upper portions. About 35 pairs of pores in petaloidal portion (Clark & Twitchell, 1915).
Posterolateral (I & V): Short; quite symmetrical. About 16 pairs of pores in petaloidal portion (Clark & Twitchell, 1915).
PORE PAIRS: Shape:
Anterolateral: Pores very unequal; anterior zone small and near together; posterior zone elongated, outer series nearly twice as large as inner (Clark & Twitchell, 1915).
Unpaired Amb: An elongated pore appears in the external rows on alternate plates; small rows closely approximated on intervening plates (Heterasterid arrangement) (Clark & Twitchell, 1915).
TUBERCLES: Primary tubercles: Numerous small tubercles scattered among granulation (Clark & Twitchell, 1915).
Granules: Surface covered with minute granulation (Clark & Twitchell, 1915).
APICAL SYSTEM: Size / Location: Small, compact; excentric and posterior (Clark & Twitchell, 1915).
Genital pores: Four large genital plates, distinctly perforated (Clark & Twitchell, 1915).
Madreporite: Right anterolateral plate occupies the center of the disk (Clark & Twitchell, 1915).
PERIPROCT (ANUS): Shape & Size: Small, oval; acuminate below (Clark & Twitchell, 1915).
Location: Situated high upon the truncated posterior margin (Clark & Twitchell, 1915).
PERISTOME (MOUTH): Shape: Transversely oblong (Clark & Twitchell, 1915).
Location: Situated in a depression near the anterior margin (Clark & Twitchell, 1915).
SPECIMENS STUDIED & CONDITION: Specimen HeTe-10 in collection of Ed Elliott.
SIZE:
Named for the state of Texas, where Roemer collected the type material (Roemer, 1852).
REMARKS & COMPARISONS
Remarks: Clark & Twitchell (1915) listed this species under Enallaster, but the description of the unpaired ambulacrum ("elongated pore appears... on alternate plates") confirms it belongs to Heteraster. True Enallaster has uniform pore pairs in the unpaired ambulacrum.
Comparisons:
Remarks: (06-2026) H. texanus had previously been wrongly reported in the Glen rose formation. It is a robust ecomorph of Heteraster obliquatus. See expanded description under H. obliquatus.
Plate: HeTe-10
Series: Lower Cretaceous Group: Fredericksburg Formation: Walnut
Locale: Harker Heights County: Bell Stage: Albian
Length: 27.1 mm Width: 23.9 mm Height: 16.2 mm
Specimen in photo: Collection of Ed Elliott
HOLOTYPE INFO:
Holotype: Described by Roemer (1852). Types likely housed at the Roemer Museum (Hildesheim) or University of Bonn, Germany.
Locality: Fredericksburg, Texas (Roemer, 1852)
Stratigraphy: Fredericksburg Group (Roemer, 1852)
SYNONYMY
- Toxaster texanus Roemer, 1852
- Enallaster texanus (Roemer, 1852) (Clark & Twitchell, 1915 usage)
- (Enallaster bosei) Lambert, 1927
- Heteraster bosei Lambert, 1927
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: HETERASTER d'Orbigny, 1853
Species: Heteraster texanus (Roemer, 1852)
TYPE SPECIES: Spatangus oblongus Brongniart, 1821
DIAGNOSIS
Test oblong, cordiform, broad in anterior portion, contracted and truncated posteriorly, with deep anterior groove. Upper surface convex, elevated; base flat, depressed at the peristome. Ambulacra narrow and unequal; posterolateral pair much shorter than others. Apical system small and compact. Periproct situated high above the margin (Clark & Twitchell, 1915).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg
Formations: Walnut Formation (Specimen); Fredericksburg, and Washita Groups (Clark & Twitchell, 1915)
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Bell County (Specimen)
DESCRIPTION
TOP: Length, width, height: 27.1 mm L × 23.9 mm W × 16.2 mm H
Top shape: Oblong, cordiform; broad in anterior portion, contracted posteriorly (Clark & Twitchell, 1915).
Top domed: Convex, elevated (Clark & Twitchell, 1915).
Sulcus: Well-defined anterior groove; narrow and slightly depressed at its head (Clark & Twitchell, 1915).
SIDE: Side shape: Rounded and inflated; posterior face truncated to the margin (Clark & Twitchell, 1915).
BOTTOM: Bottom flat: Base flat, except for peristomal depression and a central elevated region extending to the posterior border (Clark & Twitchell, 1915).
AMB: Amb arrangement: Very unequal (Clark & Twitchell, 1915).
Unpaired (III): Situated in anterior groove; wider than other areas (Clark & Twitchell, 1915).
Anterolateral (II & IV): Large; curved backward in upper portions. About 35 pairs of pores in petaloidal portion (Clark & Twitchell, 1915).
Posterolateral (I & V): Short; quite symmetrical. About 16 pairs of pores in petaloidal portion (Clark & Twitchell, 1915).
PORE PAIRS: Shape:
Anterolateral: Pores very unequal; anterior zone small and near together; posterior zone elongated, outer series nearly twice as large as inner (Clark & Twitchell, 1915).
Unpaired Amb: An elongated pore appears in the external rows on alternate plates; small rows closely approximated on intervening plates (Heterasterid arrangement) (Clark & Twitchell, 1915).
TUBERCLES: Primary tubercles: Numerous small tubercles scattered among granulation (Clark & Twitchell, 1915).
Granules: Surface covered with minute granulation (Clark & Twitchell, 1915).
APICAL SYSTEM: Size / Location: Small, compact; excentric and posterior (Clark & Twitchell, 1915).
Genital pores: Four large genital plates, distinctly perforated (Clark & Twitchell, 1915).
Madreporite: Right anterolateral plate occupies the center of the disk (Clark & Twitchell, 1915).
PERIPROCT (ANUS): Shape & Size: Small, oval; acuminate below (Clark & Twitchell, 1915).
Location: Situated high upon the truncated posterior margin (Clark & Twitchell, 1915).
PERISTOME (MOUTH): Shape: Transversely oblong (Clark & Twitchell, 1915).
Location: Situated in a depression near the anterior margin (Clark & Twitchell, 1915).
SPECIMENS STUDIED & CONDITION: Specimen HeTe-10 in collection of Ed Elliott.
SIZE:
- Holotype Size: Length 36 mm (Roemer, 1852).
- Size Range: Length 20 mm to 35 mm (Clark & Twitchell, 1915).
- Average Size: Length 30 mm to 35 mm.
Named for the state of Texas, where Roemer collected the type material (Roemer, 1852).
REMARKS & COMPARISONS
Remarks: Clark & Twitchell (1915) listed this species under Enallaster, but the description of the unpaired ambulacrum ("elongated pore appears... on alternate plates") confirms it belongs to Heteraster. True Enallaster has uniform pore pairs in the unpaired ambulacrum.
Comparisons:
- Spatangus columbianum (Lea, 1840): Clark & Twitchell suggest this may be identical to H. texanus, though the figure is indistinct.
- Enallaster peruvianus (Gabb, 1876): Clark & Twitchell considered this identical to the Texas form.
- European species: Clark & Twitchell stated no European Enallasters were closely related.
Remarks: (06-2026) H. texanus had previously been wrongly reported in the Glen rose formation. It is a robust ecomorph of Heteraster obliquatus. See expanded description under H. obliquatus.
