Diplopodia coryellensis Thompson, 2020
Plate: DiCo-10
Series: Lower Cretaceous Group: Fredericksburg Formation: Comanche Peak
Locale: Coryell County County: Coryell Stage: Albian
Length: 16.6 mm Height: 6.7 mm
Collection: Dr. Stephen Crane
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 94318 — Non-vertebrate Paleontology Laboratory, University of Texas
Paratype: NPL 94319
Locality: Coryell County, Texas
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Calycina Gregory, 1900
Order: Phymosomatoida Mortensen, 1904
Family: Emiratiidae Ali, 1990
Subfamily: Diplopodiinae Smith & Wright, 1993
Genus: DIPLOPODIA McCoy, 1848
Species: Diplopodia coryellensis Thompson, 2020
TYPE SPECIES: Diplopodia pentagona McCoy, 1848
DIAGNOSIS
A Diplopodia from the Lower Cretaceous, Fredericksburg Group, Comanche Peak Formation of Texas with 2 rows of 10 tubercles in each interambulacral area and 2 rows of 10 tubercles in each ambulacral area. Width of specimens from 16.1 mm. to 16.6 mm.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg
Formations: Comanche Peak Formation
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Coryell
DESCRIPTION
TOP: Width, height: 16.6 mm W × 6.7 mm H
Top shape: Round from above
Flatness: Flat top
SIDE: Ambitus: At midpoint
Side shape: Inflated
BOTTOM: Bottom flat: Flat bottom
Bottom shape: Slightly concave depression near peristome
SIZE: Range: Width 16.1 mm to 16.6 mm
AMB: Amb primary tubercles: Two alternating rows of 10 tubercles; one primary tubercle per plate
Amb width: 47% width of interambulacra at outer margin
Amb plating: Pentagonal; taller than wide
INTERAMB: Interamb primary tubercles: Two rows of 10 tubercles
Interamb plating: Pentagonal; slightly wider than tall
PORE PAIRS: Arrangement: Biserial adapically; uniserial around ambitus; crowded at peristome
Geminate count: 5 pore pairs per plate at ambitus and above; 4 pore pairs adorally; 5–6 pore pairs near apical system
TUBERCLES: Primary Perforated: Yes
Primary Crenulate: Yes
Primary Boss: Raised
Primary Mamelon: Pronounced
Size: Decrease in size adapically and adorally; slightly larger in interambulacra
Secondary tubercles: Scrobicular tubercles along outer edges of ambulacral and interambulacral plates
Granules: Less granulation near apical system and near peristome
APICAL SYSTEM: Size: 50% of diameter of test
Shape: Oval shaped
Plating: Caducous
PERIPROCT (ANUS): Condition: Unknown
PERISTOME (MOUTH): Size: 50% of diameter of test
Lip: Buccal notches small, not deep, invaginated
Phyllodes: No phyllodes
Sphaeridial pits: None
SPINES: Unknown
SPECIMENS STUDIED & CONDITION: Two specimens studied . Additional specimen (19.6 x 7.7 mm) from Copperas Cove noted (Kevin Durney Collection).
ETYMOLOGY: These echinoids were named for Coryell County, Texas in which they were found.
REMARKS & COMPARISONS
Remarks: The only other known Diplopodia in Texas is Diplopodia doliae Thompson, 2016. Most Diplopodia species are Jurassic, whereas this species and D. doliae are Lower Cretaceous (Albian).
Comparisons:
Plate: DiCo-10
Series: Lower Cretaceous Group: Fredericksburg Formation: Comanche Peak
Locale: Coryell County County: Coryell Stage: Albian
Length: 16.6 mm Height: 6.7 mm
Collection: Dr. Stephen Crane
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 94318 — Non-vertebrate Paleontology Laboratory, University of Texas
Paratype: NPL 94319
Locality: Coryell County, Texas
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Calycina Gregory, 1900
Order: Phymosomatoida Mortensen, 1904
Family: Emiratiidae Ali, 1990
Subfamily: Diplopodiinae Smith & Wright, 1993
Genus: DIPLOPODIA McCoy, 1848
Species: Diplopodia coryellensis Thompson, 2020
TYPE SPECIES: Diplopodia pentagona McCoy, 1848
DIAGNOSIS
A Diplopodia from the Lower Cretaceous, Fredericksburg Group, Comanche Peak Formation of Texas with 2 rows of 10 tubercles in each interambulacral area and 2 rows of 10 tubercles in each ambulacral area. Width of specimens from 16.1 mm. to 16.6 mm.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg
Formations: Comanche Peak Formation
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Coryell
DESCRIPTION
TOP: Width, height: 16.6 mm W × 6.7 mm H
Top shape: Round from above
Flatness: Flat top
SIDE: Ambitus: At midpoint
Side shape: Inflated
BOTTOM: Bottom flat: Flat bottom
Bottom shape: Slightly concave depression near peristome
SIZE: Range: Width 16.1 mm to 16.6 mm
AMB: Amb primary tubercles: Two alternating rows of 10 tubercles; one primary tubercle per plate
Amb width: 47% width of interambulacra at outer margin
Amb plating: Pentagonal; taller than wide
INTERAMB: Interamb primary tubercles: Two rows of 10 tubercles
Interamb plating: Pentagonal; slightly wider than tall
PORE PAIRS: Arrangement: Biserial adapically; uniserial around ambitus; crowded at peristome
Geminate count: 5 pore pairs per plate at ambitus and above; 4 pore pairs adorally; 5–6 pore pairs near apical system
TUBERCLES: Primary Perforated: Yes
Primary Crenulate: Yes
Primary Boss: Raised
Primary Mamelon: Pronounced
Size: Decrease in size adapically and adorally; slightly larger in interambulacra
Secondary tubercles: Scrobicular tubercles along outer edges of ambulacral and interambulacral plates
Granules: Less granulation near apical system and near peristome
APICAL SYSTEM: Size: 50% of diameter of test
Shape: Oval shaped
Plating: Caducous
PERIPROCT (ANUS): Condition: Unknown
PERISTOME (MOUTH): Size: 50% of diameter of test
Lip: Buccal notches small, not deep, invaginated
Phyllodes: No phyllodes
Sphaeridial pits: None
SPINES: Unknown
SPECIMENS STUDIED & CONDITION: Two specimens studied . Additional specimen (19.6 x 7.7 mm) from Copperas Cove noted (Kevin Durney Collection).
ETYMOLOGY: These echinoids were named for Coryell County, Texas in which they were found.
REMARKS & COMPARISONS
Remarks: The only other known Diplopodia in Texas is Diplopodia doliae Thompson, 2016. Most Diplopodia species are Jurassic, whereas this species and D. doliae are Lower Cretaceous (Albian).
Comparisons:
- Diplopodia doliae: D. coryellensis is more rounded (not barrel-shaped), has fewer interambulacral tubercles (9 vs 13 in doliae), possesses taller interambulacral plates, and has a much smaller apical scar .
