Comparisons: Thompson (2016) notes that while many cidarids have club spines, 'Cidaris' willi is distinct due to the absence of significant ornamentation.
'Cidaris' willi Thompson 2016
Plate: CiWi-10
Series: Upper Cretaceous Group: Washita Formation: Buda
Locale: Austin County: Travis Stage: Cenomanian
Length: 12.0 mm Height: 6.6 mm
Specimen in photo: NPL 70925 (Holotype), NPL 70926, NPL 70927 (Paratypes)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 70925 — Non-vertebrate Paleontology Laboratory, University of Texas
Locality: Shoal Creek, Austin, Travis County, Texas
Systematic Paleontology
CLASS: ECHINOIDEA Leske, 1778
SUBCLASS: CIDAROIDEA Smith, 1984
ORDER: CIDAROIDA Claus, 1880
FAMILY: CIDARIDAE Gray, 1825
SUBFAMILY: CIDARINAE Gray, 1825
GENUS: CIDARIS Leske, 1778
SPECIES: 'Cidaris' willi Thompson, 2016
TYPE SPECIES: Echinus cidaris Linnaeus, 1758
DIAGNOSIS: Club spines with no ornamentation. Many cidarids have similar spines, but all have ornamentation. With the plain club shaped spines, it is clearly a new species.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Buda Limestone
Stratigraphic Units: Upper Cretaceous, Cenomanian
Counties: Travis County
DESCRIPTION
(Note: Description is based entirely on isolated spines; test morphology is unknown.)
TOP: Length, height: 12.0 mm L × 6.6 mm H
SPINES: Shape: Club-shaped; spherical top end. Tapers almost perfectly (70% of length) with a slight curve from the widest point to the base end .
Widest location: About 30% down from the spherical top end .
Collar: Small, non-pronounced; located about 12% from the base end .
Base: Acetabulum perforation large; gently curved outside the perforation .
Ornamentation: Characterized by a lack of ornamentation (plain club shape); however, very minute bumps are present on the perfect spherical top .
SPECIMENS STUDIED & CONDITION
Specimen condition: Cluster of 4 spines varying in size from 5.8 mm to 12 mm .
REMARKS & COMPARISONS
Remarks: The species is assigned to the form-genus 'Cidaris' (indicated by single quotes) because the test is unknown. It is defined by its plain, club-shaped spines which lack the distinct ridges, thorns, or granules typical of other Cretaceous cidarids.
ETYMOLOGY: Named after William Brandon Thompson, the son of the author, William Thompson.
'Cidaris' willi Thompson 2016
Plate: CiWi-10
Series: Upper Cretaceous Group: Washita Formation: Buda
Locale: Austin County: Travis Stage: Cenomanian
Length: 12.0 mm Height: 6.6 mm
Specimen in photo: NPL 70925 (Holotype), NPL 70926, NPL 70927 (Paratypes)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 70925 — Non-vertebrate Paleontology Laboratory, University of Texas
Locality: Shoal Creek, Austin, Travis County, Texas
Systematic Paleontology
CLASS: ECHINOIDEA Leske, 1778
SUBCLASS: CIDAROIDEA Smith, 1984
ORDER: CIDAROIDA Claus, 1880
FAMILY: CIDARIDAE Gray, 1825
SUBFAMILY: CIDARINAE Gray, 1825
GENUS: CIDARIS Leske, 1778
SPECIES: 'Cidaris' willi Thompson, 2016
TYPE SPECIES: Echinus cidaris Linnaeus, 1758
DIAGNOSIS: Club spines with no ornamentation. Many cidarids have similar spines, but all have ornamentation. With the plain club shaped spines, it is clearly a new species.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Buda Limestone
Stratigraphic Units: Upper Cretaceous, Cenomanian
Counties: Travis County
DESCRIPTION
(Note: Description is based entirely on isolated spines; test morphology is unknown.)
TOP: Length, height: 12.0 mm L × 6.6 mm H
SPINES: Shape: Club-shaped; spherical top end. Tapers almost perfectly (70% of length) with a slight curve from the widest point to the base end .
Widest location: About 30% down from the spherical top end .
Collar: Small, non-pronounced; located about 12% from the base end .
Base: Acetabulum perforation large; gently curved outside the perforation .
Ornamentation: Characterized by a lack of ornamentation (plain club shape); however, very minute bumps are present on the perfect spherical top .
SPECIMENS STUDIED & CONDITION
Specimen condition: Cluster of 4 spines varying in size from 5.8 mm to 12 mm .
REMARKS & COMPARISONS
Remarks: The species is assigned to the form-genus 'Cidaris' (indicated by single quotes) because the test is unknown. It is defined by its plain, club-shaped spines which lack the distinct ridges, thorns, or granules typical of other Cretaceous cidarids.
ETYMOLOGY: Named after William Brandon Thompson, the son of the author, William Thompson.
