Goniophorus graysonensis Thompson, 2020
Plate: GoGr-10
Series: Upper Cretaceous Group: Washita Formation: Grayson
Locale: Trophy Club County: Denton Stage: Cenomanian
Length: 15.1 mm Height: 11.4 mm
Collection: Dr. Steven Crane
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 94324 — Non-vertebrate Paleontology Laboratory, University of Texas
Paratypes: NPL 94325
Locality: Trophy Club, Denton 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 graysonensis Thompson, 2020
TYPE SPECIES: Goniophorus lunulatus L. Agassiz, 1838
DIAGNOSIS
Large Goniophorus from Washita Group, with a flat top, with rounded periproct, large tubercles, thick with granules on genital and ocular plates, scrobicular tubercles except horizontally between interambulacral plates, and large interambulacral plates are slightly taller than wide .
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Grayson Formation
Stratigraphic Units: Upper Cretaceous, Cenomanian
Counties: Denton County
DESCRIPTION
TOP: Length, width, height: 15.1 mm L × 11.4 mm H
Top shape: Round from above; flat top
Top domed: Rounded top; apical system only slightly raised at periproct
SIDE: Ambitus: At midpoint
Side shape: Very inflated; sides steep like sides of barrel
BOTTOM: Bottom flat: Bottom flat
Bottom shape: Slightly convex on bottom
AMB: Amb shape: Lanceolate; flexuous from above, straight from midpoint to peristome
Amb width: Widest near adoral surface, narrowing at peristome
Amb primary tubercles: Two rows of staggered tubercles down center; not decreasing in size until very near apical disk and peristome
Amb granules: Aboral surface between tubercles has two alternating rows of extremely minute granules
Sphaeridial pits: Present in ambulacra, on oral surface, away from the peristome
INTERAMB: Interamb width: Almost 4 times wider than ambulacra
Interamb plating: Composed of alternating plates; large plates slightly taller than wide. Plates near apical disk thick with secondary tubercles/granules; adoral plates small and crowded with scrobicular tubercles .
Interamb primary tubercles: Two rows of staggered tubercles (seven in each row); large along sides, one small near apical disk, several smaller near peristome
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, protruding
Primary Mamelon: Large, rounded
Secondary tubercles: Scrobicular tubercles surround each large tubercle along edges of plates; naked between large plates around ambitus
APICAL SYSTEM: Size: Large; close to 57% of test from top
Shape: Much more scallop-shaped than pentagonal; 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: Suranal, genital, and ocular plates are thick with granules
Genital pores: Each genital plate perforated
PERIPROCT (ANUS): Shape & Size: Near round; 3.3 mm wide × 3.0 mm tall
PERISTOME (MOUTH): Size: Small; diameter about 30.0% of base
Shape: Rounded
Lip: Notched; notches narrow and small
SPECIMENS STUDIED & CONDITION: Several specimens studied; Holotype NPL 94324, Paratypes NPL 94325 .
ETYMOLOGY: Named after the formation from which it is found (Grayson) .
REMARKS & COMPARISONS
Remarks: Goniophorus graysonensis is distinguished by interambulacral plates that are taller than wide, a feature unlike all other Goniophorus species. The granules on the apical plates are very thick, not sporadic like G. riovistaensis.
Comparisons:
Plate: GoGr-10
Series: Upper Cretaceous Group: Washita Formation: Grayson
Locale: Trophy Club County: Denton Stage: Cenomanian
Length: 15.1 mm Height: 11.4 mm
Collection: Dr. Steven Crane
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 94324 — Non-vertebrate Paleontology Laboratory, University of Texas
Paratypes: NPL 94325
Locality: Trophy Club, Denton 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 graysonensis Thompson, 2020
TYPE SPECIES: Goniophorus lunulatus L. Agassiz, 1838
DIAGNOSIS
Large Goniophorus from Washita Group, with a flat top, with rounded periproct, large tubercles, thick with granules on genital and ocular plates, scrobicular tubercles except horizontally between interambulacral plates, and large interambulacral plates are slightly taller than wide .
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Grayson Formation
Stratigraphic Units: Upper Cretaceous, Cenomanian
Counties: Denton County
DESCRIPTION
TOP: Length, width, height: 15.1 mm L × 11.4 mm H
Top shape: Round from above; flat top
Top domed: Rounded top; apical system only slightly raised at periproct
SIDE: Ambitus: At midpoint
Side shape: Very inflated; sides steep like sides of barrel
BOTTOM: Bottom flat: Bottom flat
Bottom shape: Slightly convex on bottom
AMB: Amb shape: Lanceolate; flexuous from above, straight from midpoint to peristome
Amb width: Widest near adoral surface, narrowing at peristome
Amb primary tubercles: Two rows of staggered tubercles down center; not decreasing in size until very near apical disk and peristome
Amb granules: Aboral surface between tubercles has two alternating rows of extremely minute granules
Sphaeridial pits: Present in ambulacra, on oral surface, away from the peristome
INTERAMB: Interamb width: Almost 4 times wider than ambulacra
Interamb plating: Composed of alternating plates; large plates slightly taller than wide. Plates near apical disk thick with secondary tubercles/granules; adoral plates small and crowded with scrobicular tubercles .
Interamb primary tubercles: Two rows of staggered tubercles (seven in each row); large along sides, one small near apical disk, several smaller near peristome
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, protruding
Primary Mamelon: Large, rounded
Secondary tubercles: Scrobicular tubercles surround each large tubercle along edges of plates; naked between large plates around ambitus
APICAL SYSTEM: Size: Large; close to 57% of test from top
Shape: Much more scallop-shaped than pentagonal; 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: Suranal, genital, and ocular plates are thick with granules
Genital pores: Each genital plate perforated
PERIPROCT (ANUS): Shape & Size: Near round; 3.3 mm wide × 3.0 mm tall
PERISTOME (MOUTH): Size: Small; diameter about 30.0% of base
Shape: Rounded
Lip: Notched; notches narrow and small
SPECIMENS STUDIED & CONDITION: Several specimens studied; Holotype NPL 94324, Paratypes NPL 94325 .
ETYMOLOGY: Named after the formation from which it is found (Grayson) .
REMARKS & COMPARISONS
Remarks: Goniophorus graysonensis is distinguished by interambulacral plates that are taller than wide, a feature unlike all other Goniophorus species. The granules on the apical plates are very thick, not sporadic like G. riovistaensis.
Comparisons:
- G. whitneyi: Shares the rounded periproct shape with G. graysonensis
