Tiaromma goodlandense Thompson, 2020
Plate: TeGo-10
Series: Lower Cretaceous Group: Fredericksburg Formation: Goodland
Locale: Bryant County: Brazos Stage: Albian
Width: 26.0 mm Height: 10.1 mm
Collector: Frank Crane
Holotype: NPL 94369
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
Plate: TeGo-20
Series: Lower Cretaceous Group: Fredericksburg Formation: Goodland
Locale: Bryant County: Brazos Stage: Albian
Width: 26.0 mm Height: 10.1 mm
Collector: Frank Crane
Paratype: NPL 94370
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 94369 .
Paratype: NPL 94370 .
Locality: Bryant, Brazos County, Texas.
Stratigraphy: Goodland Limestone, Fredericksburg Group.
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: Polydiadematidae Lambert, 1900
Genus: TIAROMMA Pomel, 1883
Species: Tiaromma goodlandense Thompson, 2020
TYPE SPECIES: Diadema michelini Agassiz & Desor, 1846
DIAGNOSIS
A Tiaromma from the Goodland Limestone distinguished by having 4 rows of equal-sized tubercles in each interambulacral area (two primary rows and two secondary rows extending above the ambitus).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg
Formations: Goodland Limestone.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Brazos.
Abundance: Rare; two specimens studied.
Associated Fauna: Found in association with Heteraster texanus.
DESCRIPTION
TOP: Length, width, height: 26.0 mm W × 10.1 mm H. Top shape: Round. Top domed: Flat top.
SIDE: Ambitus: Positioned at midpoint (50% from base). Side shape: Inflated.
BOTTOM: Bottom shape: Flat; concave depression near peristome.
AMB: Amb shape: Lanceolate. Amb arrangement: Two alternating rows of 16 tubercles; one primary tubercle per plate. Zigzag band of perradial granules present. Width: Interambulacra are 2.25 times wider than ambulacra. Plating: Plates have 3 pore pairs (trigeminate) at the ambitus and below; 4 pore pairs (quadrigeminate) aborally.
PORE PAIRS: Arrangement: Uniserial; straight with a slight zigzag pattern.
TUBERCLES: Primary Perforated: Yes. Primary Crenulate: Yes. Distribution: Decrease in size adapically and adorally. Mamelons pronounced, bosses raised. Adorally, a row of small tubercles runs along the adradial sutures; tubercles largest near ambitus, reducing toward peristome.
INTERAMB: Arrangement: Four rows of equal-sized tubercles. First two rows (13 primary tubercles) run nearly perpendicular on the aboral surface. Second two rows (10 secondary tubercles) run from the peristome to above the ambitus. A third short row of smaller tubercles occurs on the adoral surface starting below the ambitus (on Holotype). Features: Interradial suture is wide and naked.
GRANULES: Distribution: Granulation present at interradial sutures.
FASCIOLE: Absent.
APICAL SYSTEM: Size: Scar 42% of diameter of test. Shape: Subpentagonal; points at both interambulacra and ambulacra. Condition: Plating caducous.
PERIPROCT (ANUS): (Unknown).
PERISTOME (MOUTH): Size: Diameter 33.8% of test. Lip: Buccal notches wide, not deep, invaginated.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Two specimens studied. Holotype NPL 94369 and Paratype NPL 94370.
ETYMOLOGY
Named for the Goodland Formation, from which it was found.
REMARKS & COMPARISONS
Remarks: Unlike other Tiaromma species, T. goodlandense possesses four rows of equal-sized tubercles in the interambulacra. The pore arrangement (uniserial with slight zigzag) and plating (quadrigeminate aborally) are consistent with the genus.
Comparisons:
Gender Emendation: The specific epithet goodlandensis (masc/fem) was emended to goodlandense (neuter) to comply with the gender of the genus Tiaromma.
Plate: TeGo-10
Series: Lower Cretaceous Group: Fredericksburg Formation: Goodland
Locale: Bryant County: Brazos Stage: Albian
Width: 26.0 mm Height: 10.1 mm
Collector: Frank Crane
Holotype: NPL 94369
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
Plate: TeGo-20
Series: Lower Cretaceous Group: Fredericksburg Formation: Goodland
Locale: Bryant County: Brazos Stage: Albian
Width: 26.0 mm Height: 10.1 mm
Collector: Frank Crane
Paratype: NPL 94370
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 94369 .
Paratype: NPL 94370 .
Locality: Bryant, Brazos County, Texas.
Stratigraphy: Goodland Limestone, Fredericksburg Group.
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: Polydiadematidae Lambert, 1900
Genus: TIAROMMA Pomel, 1883
Species: Tiaromma goodlandense Thompson, 2020
TYPE SPECIES: Diadema michelini Agassiz & Desor, 1846
DIAGNOSIS
A Tiaromma from the Goodland Limestone distinguished by having 4 rows of equal-sized tubercles in each interambulacral area (two primary rows and two secondary rows extending above the ambitus).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg
Formations: Goodland Limestone.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Brazos.
Abundance: Rare; two specimens studied.
Associated Fauna: Found in association with Heteraster texanus.
DESCRIPTION
TOP: Length, width, height: 26.0 mm W × 10.1 mm H. Top shape: Round. Top domed: Flat top.
SIDE: Ambitus: Positioned at midpoint (50% from base). Side shape: Inflated.
BOTTOM: Bottom shape: Flat; concave depression near peristome.
AMB: Amb shape: Lanceolate. Amb arrangement: Two alternating rows of 16 tubercles; one primary tubercle per plate. Zigzag band of perradial granules present. Width: Interambulacra are 2.25 times wider than ambulacra. Plating: Plates have 3 pore pairs (trigeminate) at the ambitus and below; 4 pore pairs (quadrigeminate) aborally.
PORE PAIRS: Arrangement: Uniserial; straight with a slight zigzag pattern.
TUBERCLES: Primary Perforated: Yes. Primary Crenulate: Yes. Distribution: Decrease in size adapically and adorally. Mamelons pronounced, bosses raised. Adorally, a row of small tubercles runs along the adradial sutures; tubercles largest near ambitus, reducing toward peristome.
INTERAMB: Arrangement: Four rows of equal-sized tubercles. First two rows (13 primary tubercles) run nearly perpendicular on the aboral surface. Second two rows (10 secondary tubercles) run from the peristome to above the ambitus. A third short row of smaller tubercles occurs on the adoral surface starting below the ambitus (on Holotype). Features: Interradial suture is wide and naked.
GRANULES: Distribution: Granulation present at interradial sutures.
FASCIOLE: Absent.
APICAL SYSTEM: Size: Scar 42% of diameter of test. Shape: Subpentagonal; points at both interambulacra and ambulacra. Condition: Plating caducous.
PERIPROCT (ANUS): (Unknown).
PERISTOME (MOUTH): Size: Diameter 33.8% of test. Lip: Buccal notches wide, not deep, invaginated.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Two specimens studied. Holotype NPL 94369 and Paratype NPL 94370.
ETYMOLOGY
Named for the Goodland Formation, from which it was found.
REMARKS & COMPARISONS
Remarks: Unlike other Tiaromma species, T. goodlandense possesses four rows of equal-sized tubercles in the interambulacra. The pore arrangement (uniserial with slight zigzag) and plating (quadrigeminate aborally) are consistent with the genus.
Comparisons:
- Tiaromma michelini: T. goodlandense has more tubercles in the two primary ambulacral rows than T. michelini.
Gender Emendation: The specific epithet goodlandensis (masc/fem) was emended to goodlandense (neuter) to comply with the gender of the genus Tiaromma.
