Desoricidaris tarrantensis Thompson 2016
Plate: DeTa-10
Series: Lower Cretaceous Group: Washita Formation: Main Street
Locale: Fort Worth County: Tarrant Stage: Cenomanian
Length: 24.0 mm Height: 14.3 mm
Specimen in photo: NPL 82989 (Holotype)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 82989 — Non-vertebrate Paleontology Laboratory, University of Texas
Locality: Fort Worth, Tarrant County, Texas
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Cidaroidea Smith, 1984
Order: Cidaroida Claus, 1880
Family: Cidaridae Gray, 1825
Subfamily: Stereocidarinae Lambert, 1900
Genus: DESORICIDARIS Geys, 1992
Species: Desoricidaris tarrantensis Thompson, 2016
TYPE SPECIES: Rhabdocidaris pouyannei Cotteau, 1863
DIAGNOSIS
A Desoricidaris from the upper Main Street Formation of central Texas with most of the tubercles above the ambitus not developed and with less granulation vertically between developed tubercles at the ambitus and below .
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Main Street Formation
Stratigraphic Units: Lower Cretaceous, Cenomanian
Counties: Tarrant County
DESCRIPTION
TOP: Length, width, height: 24.0 mm L × 14.3 mm H
Top shape: Round, sub-pentagonal shaped from above
Flatness: Flat top
SIDE: Ambitus: 45% from the base
Side shape: Inflated with curved sides
BOTTOM: Bottom flat: Flat bottom; adoral surface concave
AMB: Amb shape: Flexed; pointed at apical system, widest at margin, only slightly narrowing at peristome
Amb primary tubercles: A row of tubercles runs entire length (excluding aboral narrowing); row of perradial smaller tubercles and granules present
Amb arrangement: Plating simple
INTERAMB: Interamb width: 3.25 times wider than ambulacra at the margin
Interamb plating: Two rows of 4 to 5 plates
Sutures: Depressed
PORE PAIRS: Shape: Small, oblique
Arrangement: Uniserial
Conjugate vs Nonconjugate: Strongly conjugated, joined by a groove
TUBERCLES: Primary tubercles: Large at ambitus . Adapically tubercles not fully developed .
Primary Perforated: Yes
Primary Crenulate: No
Primary Areola shape: Deeply impressed
Secondary tubercles: Scrobicular tubercles differentiated
Granules: Plates covered in dense granules
APICAL SYSTEM: Size: Very large; measures 52% of width of test
Location: Central
Condition: Missing
PERIPROCT (ANUS): Condition: Missing
PERISTOME (MOUTH): Size: Measures 46% of width of test
Shape: Round; smaller than apical system
SPECIMENS STUDIED & CONDITION
Specimen condition: Holotype NPL 82989 .
ETYMOLOGY
This fossil named after the location it was found, Tarrant County .
REMARKS & COMPARISONS
Remarks: Other species such as Desoricidaris pouyannei and Desoricidaris balli have more developed primary tubercles adorally and more granulation between the tubercles vertically .
Plate: DeTa-10
Series: Lower Cretaceous Group: Washita Formation: Main Street
Locale: Fort Worth County: Tarrant Stage: Cenomanian
Length: 24.0 mm Height: 14.3 mm
Specimen in photo: NPL 82989 (Holotype)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 82989 — Non-vertebrate Paleontology Laboratory, University of Texas
Locality: Fort Worth, Tarrant County, Texas
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Cidaroidea Smith, 1984
Order: Cidaroida Claus, 1880
Family: Cidaridae Gray, 1825
Subfamily: Stereocidarinae Lambert, 1900
Genus: DESORICIDARIS Geys, 1992
Species: Desoricidaris tarrantensis Thompson, 2016
TYPE SPECIES: Rhabdocidaris pouyannei Cotteau, 1863
DIAGNOSIS
A Desoricidaris from the upper Main Street Formation of central Texas with most of the tubercles above the ambitus not developed and with less granulation vertically between developed tubercles at the ambitus and below .
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Main Street Formation
Stratigraphic Units: Lower Cretaceous, Cenomanian
Counties: Tarrant County
DESCRIPTION
TOP: Length, width, height: 24.0 mm L × 14.3 mm H
Top shape: Round, sub-pentagonal shaped from above
Flatness: Flat top
SIDE: Ambitus: 45% from the base
Side shape: Inflated with curved sides
BOTTOM: Bottom flat: Flat bottom; adoral surface concave
AMB: Amb shape: Flexed; pointed at apical system, widest at margin, only slightly narrowing at peristome
Amb primary tubercles: A row of tubercles runs entire length (excluding aboral narrowing); row of perradial smaller tubercles and granules present
Amb arrangement: Plating simple
INTERAMB: Interamb width: 3.25 times wider than ambulacra at the margin
Interamb plating: Two rows of 4 to 5 plates
Sutures: Depressed
PORE PAIRS: Shape: Small, oblique
Arrangement: Uniserial
Conjugate vs Nonconjugate: Strongly conjugated, joined by a groove
TUBERCLES: Primary tubercles: Large at ambitus . Adapically tubercles not fully developed .
Primary Perforated: Yes
Primary Crenulate: No
Primary Areola shape: Deeply impressed
Secondary tubercles: Scrobicular tubercles differentiated
Granules: Plates covered in dense granules
APICAL SYSTEM: Size: Very large; measures 52% of width of test
Location: Central
Condition: Missing
PERIPROCT (ANUS): Condition: Missing
PERISTOME (MOUTH): Size: Measures 46% of width of test
Shape: Round; smaller than apical system
SPECIMENS STUDIED & CONDITION
Specimen condition: Holotype NPL 82989 .
ETYMOLOGY
This fossil named after the location it was found, Tarrant County .
REMARKS & COMPARISONS
Remarks: Other species such as Desoricidaris pouyannei and Desoricidaris balli have more developed primary tubercles adorally and more granulation between the tubercles vertically .
