Hemiaster sabinal Cooke, 1953
Plate: HeSa-10
Series: Upper Cretaceous Group: Austin Formation: Austin Chalk
Locale: Sabinal River County: Uvalde Stage: Santonian
Length: 70.6 mm Width: 68.9 mm Height: 37.3 mm
Specimen in photo: U.S.N.M. 108400 Holotype
Paleobiology Depart. NMNH, Smithsonian Institution Red Ink.
Plate: HeSa-20
Series: Upper Cretaceous Group: Austin Formation: Austin Chalk
Locale: Blewett County: Uvalde Stage: Santonian
Length: 37.8 mm Width: 33.7 mm Height: 26.9 mm
Collection: Bill Thompson
HOLOTYPE INFO:
Holotype: USNM 108400 — National Museum of Natural History, Smithsonian Institution (Cooke, 1953)
Locality: Sabinal River, Uvalde County, Texas (Cooke, 1953)
Stratigraphy: Austin Chalk (Cooke, 1953)
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: Hemiasteridae L. Clark, 1917
Genus: HEMIASTER L. Agassiz, 1847
Species: Hemiaster sabinal Cooke, 1953
TYPE SPECIES: Spatangus bufo Brongniart, 1822
DIAGNOSIS
Test large; upper surface high with a posterior keel; deep anterior furrow indenting the margin. Peripetalous fasciole strongly indented between the lateral petals (Cooke, 1953).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Austin (Cooke, 1953)
Formations: Austin Chalk (Cooke, 1953)
Stratigraphic Units: Upper Cretaceous, Coniacian or Santonian (Cooke, 1953)
Counties: Uvalde County (Cooke, 1953)
DESCRIPTION
TOP: Length, width, height: 70.6 mm L × 68.9 mm W × 37.3 mm H (Holotype); 37.8 mm L × 33.7 mm W × 26.9 mm H (HeSa-20).
Top shape: High upper surface; highest point on the posterior keel (Cooke, 1953).
Top domed: Broad, gently sloping posterior truncation (Cooke, 1953).
SIDE: Side shape: Anterior end geniculated, though the geniculation may be increased by crushing (Cooke, 1953).
BOTTOM: Bottom shape: Lower surface rounded; transverse furrow passes across the peristome (Cooke, 1953).
Sulcus: Deep, rounded furrow extending from the peristome through the anterior ambulacrum to the apical system and indenting the margin (Cooke, 1953).
AMB: Amb shape: Paired petals deeply sunken. Anterior pair straight, widely spreading, long; posterior pair somewhat shorter, curved backward, not widely spreading (Cooke, 1953).
Amb arrangement: Anterior ambulacrum separated by a bead (Cooke, 1953).
PORE PAIRS: Shape: Pores of paired petals elongated; pores of anterior ambulacrum small, round (Cooke, 1953).
Conjugate vs Nonconjugate: Paired pores conjugate (Cooke, 1953).
FASCIOLE: Peripetalous fasciole strongly indented between the lateral petals (Cooke, 1953).
APICAL SYSTEM: Location: Front of the center.
PERIPROCT (ANUS): Shape & Size: Longitudinally elongated (Cooke, 1953).
Location: High up on the posterior slope (Cooke, 1953).
Visibility: Plainly visible from above (Cooke, 1953).
PERISTOME (MOUTH): Location: Not far forward (Cooke, 1953).
Shape: Transversely elongated; anterior sides nearly straight (Cooke, 1953).
Lip: High, narrow lip behind (Cooke, 1953).
SPECIMENS STUDIED & CONDITION: Holotype USNM 108400 (Red Ink on specimen). Second specimen from Bill Thompson collection.
ETYMOLOGY
Named for the Sabinal River in Uvalde County, Texas, the type locality (Cooke, 1953).
REMARKS & COMPARISONS
Comparisons: Hemiaster sabinal is much larger than Hemiaster texanus Roemer. H. texanus differs by having a central apical system, straight posterior petals, a steeper posterior slope, and a fasciole without indentations (Cooke, 1953).
Plate: HeSa-10
Series: Upper Cretaceous Group: Austin Formation: Austin Chalk
Locale: Sabinal River County: Uvalde Stage: Santonian
Length: 70.6 mm Width: 68.9 mm Height: 37.3 mm
Specimen in photo: U.S.N.M. 108400 Holotype
Paleobiology Depart. NMNH, Smithsonian Institution Red Ink.
Plate: HeSa-20
Series: Upper Cretaceous Group: Austin Formation: Austin Chalk
Locale: Blewett County: Uvalde Stage: Santonian
Length: 37.8 mm Width: 33.7 mm Height: 26.9 mm
Collection: Bill Thompson
HOLOTYPE INFO:
Holotype: USNM 108400 — National Museum of Natural History, Smithsonian Institution (Cooke, 1953)
Locality: Sabinal River, Uvalde County, Texas (Cooke, 1953)
Stratigraphy: Austin Chalk (Cooke, 1953)
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: Hemiasteridae L. Clark, 1917
Genus: HEMIASTER L. Agassiz, 1847
Species: Hemiaster sabinal Cooke, 1953
TYPE SPECIES: Spatangus bufo Brongniart, 1822
DIAGNOSIS
Test large; upper surface high with a posterior keel; deep anterior furrow indenting the margin. Peripetalous fasciole strongly indented between the lateral petals (Cooke, 1953).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Austin (Cooke, 1953)
Formations: Austin Chalk (Cooke, 1953)
Stratigraphic Units: Upper Cretaceous, Coniacian or Santonian (Cooke, 1953)
Counties: Uvalde County (Cooke, 1953)
DESCRIPTION
TOP: Length, width, height: 70.6 mm L × 68.9 mm W × 37.3 mm H (Holotype); 37.8 mm L × 33.7 mm W × 26.9 mm H (HeSa-20).
Top shape: High upper surface; highest point on the posterior keel (Cooke, 1953).
Top domed: Broad, gently sloping posterior truncation (Cooke, 1953).
SIDE: Side shape: Anterior end geniculated, though the geniculation may be increased by crushing (Cooke, 1953).
BOTTOM: Bottom shape: Lower surface rounded; transverse furrow passes across the peristome (Cooke, 1953).
Sulcus: Deep, rounded furrow extending from the peristome through the anterior ambulacrum to the apical system and indenting the margin (Cooke, 1953).
AMB: Amb shape: Paired petals deeply sunken. Anterior pair straight, widely spreading, long; posterior pair somewhat shorter, curved backward, not widely spreading (Cooke, 1953).
Amb arrangement: Anterior ambulacrum separated by a bead (Cooke, 1953).
PORE PAIRS: Shape: Pores of paired petals elongated; pores of anterior ambulacrum small, round (Cooke, 1953).
Conjugate vs Nonconjugate: Paired pores conjugate (Cooke, 1953).
FASCIOLE: Peripetalous fasciole strongly indented between the lateral petals (Cooke, 1953).
APICAL SYSTEM: Location: Front of the center.
PERIPROCT (ANUS): Shape & Size: Longitudinally elongated (Cooke, 1953).
Location: High up on the posterior slope (Cooke, 1953).
Visibility: Plainly visible from above (Cooke, 1953).
PERISTOME (MOUTH): Location: Not far forward (Cooke, 1953).
Shape: Transversely elongated; anterior sides nearly straight (Cooke, 1953).
Lip: High, narrow lip behind (Cooke, 1953).
SPECIMENS STUDIED & CONDITION: Holotype USNM 108400 (Red Ink on specimen). Second specimen from Bill Thompson collection.
ETYMOLOGY
Named for the Sabinal River in Uvalde County, Texas, the type locality (Cooke, 1953).
REMARKS & COMPARISONS
Comparisons: Hemiaster sabinal is much larger than Hemiaster texanus Roemer. H. texanus differs by having a central apical system, straight posterior petals, a steeper posterior slope, and a fasciole without indentations (Cooke, 1953).
