Goniophorus riovistaensis Thompson, 2020
Plate: GoRi-10
Series: Lower Cretaceous Group: Washita Formation: Weno Pawpaw
Locale: Rio Vista County: Johnson Stage: Albian
Length: 15.5 mm Height: 11.9 mm
Collection: Dr. Steven Crane
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 94327 — Non-vertebrate Paleontology Laboratory, University of Texas
Paratypes: NPL 94328
Locality: Rio Vista, Johnson County, Texas
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Calycina Gregory, 1900
Order: Salenioida Delage & Hérouard, 1903
Family: Saleniidae L. Agassiz, 1838
Subfamily: Hyposaleniinae Mortensen, 1934
Genus: GONIOPHORUS L. Agassiz, 1838
Species: Goniophorus riovistaensis Thompson, 2020
TYPE SPECIES: Goniophorus lunulatus L. Agassiz, 1838
DIAGNOSIS
Large Goniophorus from Washita Group, with triangular periproct, relatively small tubercles, rows of small granules on genital and ocular plates, and scrobicular tubercles surround interambulacral plates .
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Weno Formation, Pawpaw Formation
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Johnson County
DESCRIPTION
TOP: Length, width, height: 15.5 mm L × 11.9 mm H
Top shape: Round from above
Top domed: Slightly pointed on top; apical system only slightly raised at periproct
SIDE: Ambitus: 35% from base
Side shape: Very inflated; sides steep like sides of barrel, rounded
BOTTOM: Bottom flat: Bottom flat; slightly convex
SIZE: Range: 13.6 mm to 20.4 mm Length
AMB: Amb shape: Lanceolate, flexuous; widest at ambitus, slightly narrowing at peristome
Amb primary tubercles: Two rows of staggered tubercles down center; decreasing in size from ambitus to apical system
Amb granules: Aboral surface between tubercles has two alternating rows of granules; aboral granules numerous and large
Sphaeridial pits: Present in ambulacra, on oral surface, away from the peristome
INTERAMB: Interamb width: Almost 5 times wider than ambulacra
Interamb plating: Alternating plates; slightly wider than tall
Interamb primary tubercles: Two rows of staggered tubercles with five in each row
Interamb granules: Secondary tubercles and granules below ambitus and continue to aboral surface where they are numerous and large
PORE PAIRS: Shape: Round
Arrangement: Bigeminate adorally and unigeminate at ambitus and aborally; offset
TUBERCLES: Primary Perforated: Imperforate
Primary Crenulate: Yes; distinctively crenulate
Primary Boss: Large, raised
Primary Mamelon: Small and rounded upon large platforms
Secondary tubercles: Scrobicular tubercles surround each large tubercle along edges of plates
APICAL SYSTEM: Size: Very large; close to 49% of test from top
Shape: Scallop shaped; sits mostly flat on corona
Plates: 5 oculars, 5 genitals, 1 suranal. Genitals 8-sided. Oculars fat, pointed in center and ends, indented at ambulacra
Ornamentation: Rows of small granules on genital and ocular plates
Genital pores: Each genital plate perforated
PERIPROCT (ANUS): Shape & Size: Triangular; rounded above; 3.5 mm
PERISTOME (MOUTH): Size: Small; diameter about 15.5% of base
Shape: Rounded
Lip: Notched; notches small
SPECIMENS STUDIED & CONDITION: Four specimens studied; Holotype NPL 94327.
ETYMOLOGY: Named after the town from which it is found
REMARKS & COMPARISONS
Remarks: The triangular periproct resembles that of Goniophorus scotti. Granules on apical plates are much more sporadic than in G. graysonensis. Interambulacral mamelons are much smaller than in other Goniophorus species. Aboral surface secondary tubercles and granules are larger than in other Goniophorus species. Interambulacral plates are wider than tall, unlike G. graysonensis .
Plate: GoRi-10
Series: Lower Cretaceous Group: Washita Formation: Weno Pawpaw
Locale: Rio Vista County: Johnson Stage: Albian
Length: 15.5 mm Height: 11.9 mm
Collection: Dr. Steven Crane
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 94327 — Non-vertebrate Paleontology Laboratory, University of Texas
Paratypes: NPL 94328
Locality: Rio Vista, Johnson County, Texas
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Calycina Gregory, 1900
Order: Salenioida Delage & Hérouard, 1903
Family: Saleniidae L. Agassiz, 1838
Subfamily: Hyposaleniinae Mortensen, 1934
Genus: GONIOPHORUS L. Agassiz, 1838
Species: Goniophorus riovistaensis Thompson, 2020
TYPE SPECIES: Goniophorus lunulatus L. Agassiz, 1838
DIAGNOSIS
Large Goniophorus from Washita Group, with triangular periproct, relatively small tubercles, rows of small granules on genital and ocular plates, and scrobicular tubercles surround interambulacral plates .
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Weno Formation, Pawpaw Formation
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Johnson County
DESCRIPTION
TOP: Length, width, height: 15.5 mm L × 11.9 mm H
Top shape: Round from above
Top domed: Slightly pointed on top; apical system only slightly raised at periproct
SIDE: Ambitus: 35% from base
Side shape: Very inflated; sides steep like sides of barrel, rounded
BOTTOM: Bottom flat: Bottom flat; slightly convex
SIZE: Range: 13.6 mm to 20.4 mm Length
AMB: Amb shape: Lanceolate, flexuous; widest at ambitus, slightly narrowing at peristome
Amb primary tubercles: Two rows of staggered tubercles down center; decreasing in size from ambitus to apical system
Amb granules: Aboral surface between tubercles has two alternating rows of granules; aboral granules numerous and large
Sphaeridial pits: Present in ambulacra, on oral surface, away from the peristome
INTERAMB: Interamb width: Almost 5 times wider than ambulacra
Interamb plating: Alternating plates; slightly wider than tall
Interamb primary tubercles: Two rows of staggered tubercles with five in each row
Interamb granules: Secondary tubercles and granules below ambitus and continue to aboral surface where they are numerous and large
PORE PAIRS: Shape: Round
Arrangement: Bigeminate adorally and unigeminate at ambitus and aborally; offset
TUBERCLES: Primary Perforated: Imperforate
Primary Crenulate: Yes; distinctively crenulate
Primary Boss: Large, raised
Primary Mamelon: Small and rounded upon large platforms
Secondary tubercles: Scrobicular tubercles surround each large tubercle along edges of plates
APICAL SYSTEM: Size: Very large; close to 49% of test from top
Shape: Scallop shaped; sits mostly flat on corona
Plates: 5 oculars, 5 genitals, 1 suranal. Genitals 8-sided. Oculars fat, pointed in center and ends, indented at ambulacra
Ornamentation: Rows of small granules on genital and ocular plates
Genital pores: Each genital plate perforated
PERIPROCT (ANUS): Shape & Size: Triangular; rounded above; 3.5 mm
PERISTOME (MOUTH): Size: Small; diameter about 15.5% of base
Shape: Rounded
Lip: Notched; notches small
SPECIMENS STUDIED & CONDITION: Four specimens studied; Holotype NPL 94327.
ETYMOLOGY: Named after the town from which it is found
REMARKS & COMPARISONS
Remarks: The triangular periproct resembles that of Goniophorus scotti. Granules on apical plates are much more sporadic than in G. graysonensis. Interambulacral mamelons are much smaller than in other Goniophorus species. Aboral surface secondary tubercles and granules are larger than in other Goniophorus species. Interambulacral plates are wider than tall, unlike G. graysonensis .
