Hemiaster wetherbyi de Loriol, 1887
Plate: HeWe-10
Series: Upper Cretaceous Group: Navarro Formation: Corsicana in Texas
Locale: San Antonio, Texas County: Bexar, Texas Stage: Maastrichtian
Length: 24.4 mm Width: 23.1 mm Height: 17.4 mm
Specimen in photo: U.S.N.M. 108398 Type
Paleobiology Depart. NMNH, Smithsonian Institution
Specimen in photo from Mississippi. Red Ink.
HOLOTYPE INFO:
Holotype: De Loriol's types are typically housed in the Natural History Museum of Geneva. USNM 108398 is a hypotype figured by Cooke (1953).
Locality: "Ripley Group," Mississippi (de Loriol, 1887).
Stratigraphy: Ripley Formation (equivalent to Navarro Group) (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 wetherbyi de Loriol, 1887
TYPE SPECIES: Spatangus bufo Brongniart, 1822
DIAGNOSIS
Test small, plump, subovate. Paired petals straight, closed, moderately sunken; anterior pair twice as long as posterior. Pores of unpaired ambulacrum separated by a conspicuous bead. Peripetalous fasciole broad and conspicuous (Cooke, 1953).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Navarro (Texas); Selma (Mississippi) (Cooke, 1953)
Formations: Corsicana Formation (Texas); Ripley Formation (Mississippi) (Cooke, 1953)
Stratigraphic Units: Upper Cretaceous, Maastrichtian (Cooke, 1953)
Counties: Bexar (Texas); Mississippi localities (Cooke, 1953)
DESCRIPTION
TOP: Length, width, height: 24.4 mm L × 23.1 mm W × 17.4 mm H (Cooke, 1953)
Top shape: Subovate; margin rounded (Cooke, 1953)
Top domed: Upper surface somewhat higher behind (Cooke, 1953)
SIDE: Side shape: Plump; truncated behind (Cooke, 1953)
BOTTOM: Bottom shape: Inflated (Cooke, 1953)
AMB: Amb shape: Paired petals wide, straight, closed, moderately sunken (Cooke, 1953)
Amb arrangement: Anterior pair twice as long as posterior pair (Cooke, 1953)
Amb width: Poriferous zones wider than interporiferous zones in paired petals (Cooke, 1953)
Unpaired Amb: Straight, open, moderately sunken; depression barely indents the margin (Cooke, 1953)
PORE PAIRS: Shape: Paired petal pores elongate-oval to drop-shaped; connected by a raised thread. Anterior petal pores small; zygopores short (Cooke, 1953).
Ornamentation: Pores of anterior ambulacrum separated by a conspicuous bead (Cooke, 1953)
TUBERCLES: Primary tubercles: Large, close together, scrobiculate (sunken); larger and more deeply scrobiculate on lower surface (Cooke, 1953)
Sternum: Bordered by broad, straight rugose bands (Cooke, 1953)
FASCIOLE: Peripetalous fasciole broad, conspicuous; barely indented between the petals (Cooke, 1953)
APICAL SYSTEM: Location: Behind the center (Cooke, 1953)
Genital pores: Inconspicuous (Cooke, 1953)
Madreporite: Large and tumid (Cooke, 1953)
PERIPROCT (ANUS): Shape & Size: Small, slightly elongated longitudinally (Cooke, 1953)
Location: Well up on the vertical posterior truncation (Cooke, 1953)
PERISTOME (MOUTH): Location: Anterior; one-third the total length from the margin (Cooke, 1953)
Lip: Strongly labiate behind (Cooke, 1953)
Sternal Plates: Not symmetrical, left sternal plate dominating in size and arrangement above right sternal plate.
SPECIMENS STUDIED & CONDITION: Specimen USNM 108398 (Type) (Cooke, 1953).
ETYMOLOGY
Named in honor of Albert Gallatin Wetherby (1833–1902), an American malacologist and fossil collector who supplied material to de Loriol.
REMARKS & COMPARISONS
Remarks: This species can be separated from Hemiaster bexari by the presence of large beads between the pore pairs in the unpaired ambulacrum. Cooke’s description says “zygo-pores very narrow, pores separated by an erect, flattened bead.
Comparisons:
Plate: HeWe-10
Series: Upper Cretaceous Group: Navarro Formation: Corsicana in Texas
Locale: San Antonio, Texas County: Bexar, Texas Stage: Maastrichtian
Length: 24.4 mm Width: 23.1 mm Height: 17.4 mm
Specimen in photo: U.S.N.M. 108398 Type
Paleobiology Depart. NMNH, Smithsonian Institution
Specimen in photo from Mississippi. Red Ink.
HOLOTYPE INFO:
Holotype: De Loriol's types are typically housed in the Natural History Museum of Geneva. USNM 108398 is a hypotype figured by Cooke (1953).
Locality: "Ripley Group," Mississippi (de Loriol, 1887).
Stratigraphy: Ripley Formation (equivalent to Navarro Group) (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 wetherbyi de Loriol, 1887
TYPE SPECIES: Spatangus bufo Brongniart, 1822
DIAGNOSIS
Test small, plump, subovate. Paired petals straight, closed, moderately sunken; anterior pair twice as long as posterior. Pores of unpaired ambulacrum separated by a conspicuous bead. Peripetalous fasciole broad and conspicuous (Cooke, 1953).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Navarro (Texas); Selma (Mississippi) (Cooke, 1953)
Formations: Corsicana Formation (Texas); Ripley Formation (Mississippi) (Cooke, 1953)
Stratigraphic Units: Upper Cretaceous, Maastrichtian (Cooke, 1953)
Counties: Bexar (Texas); Mississippi localities (Cooke, 1953)
DESCRIPTION
TOP: Length, width, height: 24.4 mm L × 23.1 mm W × 17.4 mm H (Cooke, 1953)
Top shape: Subovate; margin rounded (Cooke, 1953)
Top domed: Upper surface somewhat higher behind (Cooke, 1953)
SIDE: Side shape: Plump; truncated behind (Cooke, 1953)
BOTTOM: Bottom shape: Inflated (Cooke, 1953)
AMB: Amb shape: Paired petals wide, straight, closed, moderately sunken (Cooke, 1953)
Amb arrangement: Anterior pair twice as long as posterior pair (Cooke, 1953)
Amb width: Poriferous zones wider than interporiferous zones in paired petals (Cooke, 1953)
Unpaired Amb: Straight, open, moderately sunken; depression barely indents the margin (Cooke, 1953)
PORE PAIRS: Shape: Paired petal pores elongate-oval to drop-shaped; connected by a raised thread. Anterior petal pores small; zygopores short (Cooke, 1953).
Ornamentation: Pores of anterior ambulacrum separated by a conspicuous bead (Cooke, 1953)
TUBERCLES: Primary tubercles: Large, close together, scrobiculate (sunken); larger and more deeply scrobiculate on lower surface (Cooke, 1953)
Sternum: Bordered by broad, straight rugose bands (Cooke, 1953)
FASCIOLE: Peripetalous fasciole broad, conspicuous; barely indented between the petals (Cooke, 1953)
APICAL SYSTEM: Location: Behind the center (Cooke, 1953)
Genital pores: Inconspicuous (Cooke, 1953)
Madreporite: Large and tumid (Cooke, 1953)
PERIPROCT (ANUS): Shape & Size: Small, slightly elongated longitudinally (Cooke, 1953)
Location: Well up on the vertical posterior truncation (Cooke, 1953)
PERISTOME (MOUTH): Location: Anterior; one-third the total length from the margin (Cooke, 1953)
Lip: Strongly labiate behind (Cooke, 1953)
Sternal Plates: Not symmetrical, left sternal plate dominating in size and arrangement above right sternal plate.
SPECIMENS STUDIED & CONDITION: Specimen USNM 108398 (Type) (Cooke, 1953).
ETYMOLOGY
Named in honor of Albert Gallatin Wetherby (1833–1902), an American malacologist and fossil collector who supplied material to de Loriol.
REMARKS & COMPARISONS
Remarks: This species can be separated from Hemiaster bexari by the presence of large beads between the pore pairs in the unpaired ambulacrum. Cooke’s description says “zygo-pores very narrow, pores separated by an erect, flattened bead.
Comparisons:
- Hemiaster stella: H. wetherbyi differs in shape and apical plate arrangement. Historically mistaken for H. stella by Morton and Clark (Cooke, 1953).
- Hemiaster bufo: H. wetherbyi is higher in front and lower behind than H. bufo (Cooke, 1953).
- Hemiaster arcolensis: H. wetherbyi is easily distinguishable by its sunken (scrobiculate) tubercles, whereas H. arcolensis tubercles are not sunken (Cooke, 1953).
