Pygaster sp. (in Manuscript)
Plate: PySp-10
Series: Lower Cretaceous Group: Trinity Formation: Glen rose
Locale: Startzville County: Comal Stage: Albian
Length: 20.6 mm Width: 24.9 mm Height: 7.6 mm
Collector: Ed Elliott
Specimen in photograph NPL 94356
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
FIGURED SPECIMEN INFO:
Specimen: NPL 94356.
Locality: Startzville, Comal County, Texas.
Stratigraphy: Glen Rose Formation, Trinity Group.
SYNONYMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Order: Pygasteroida Durham & Melville, 1957
Family: Pygasteridae Lambert, 1900
Genus: PYGASTER L. Agassiz, 1836
Species: Pygaster sp.
TYPE SPECIES: Clypeus semisulcatus Phillips, 1829
DIAGNOSIS
A Pygaster from the Glen Rose Formation characterized by a test that is much wider than tall (transverse oval) with a squat profile. The periproct is teardrop-shaped and continuous with the apical system.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Trinity
Formations: Glen Rose Formation.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Comal.
Abundance: Rare; four specimens found (one complete).
DESCRIPTION
TOP: Length, width, height: 20.6 mm L × 24.9 mm W × 7.6 mm H. Top shape: Transverse oval (wider than long). Top domed: Apical system positioned anterior of center.
SIDE: Ambitus: Positioned 40% of height from the adoral side. Side shape: Inflated with rounded sides.
BOTTOM: Bottom shape: Adoral surface concave.
AMB: Amb shape: Lanceolate; pointed at apical system, widest at margin. Amb arrangement: Secondary tubercles present in perradial area starting 1/3 above and 1/3 below the margin. Width: Interambulacra are 2.5 times wider than ambulacra at the margin. Plating: Trigeminate throughout.
PORE PAIRS: Arrangement: Uniserial. Shape: Small and round.
TUBERCLES: Primary Perforated: Yes.
Primary Crenulate: Yes.
Ambulacral Tubercles: A row of primary tubercles runs next to the pore pairs aborally.
Interambulacral Tubercles: Aborally, two rows of primary tubercles run the entire length. Adorally, six rows of primary tubercles and two rows of secondary tubercles (starting just below margin) are present. Rows of secondary tubercles run 1/2 to 1/3 above and below the margin on either side of the primaries.
Areolas: Sunken. Bosses: Protruding. Scrobicular Tubercles: Surround primary and secondary tubercles.
GRANULES: See Tubercles.
FASCIOLE: Absent in Pygasteridae.
INTERAMB: Shape: Plates slightly wider than tall.
APICAL SYSTEM: Location: Anterior of center. Condition: Missing in specimen; joined with periproct creating a keyhole pattern.
PERIPROCT (ANUS): Shape: Large, teardrop shaped; length almost 1.5 times the width. Location: Aboral; no plates present between it and the apical system (confluent).
PERISTOME (MOUTH): Size: Small (1/3 size of test); larger than apical system. Shape: Oval. Lip: Notches small and faint.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: One complete crushed specimen (NPL 94356) and plates from three other specimens (including NPL 94357). Found by Ed Elliott.
ETYMOLOGY
[Not Applicable; open nomenclature].
REMARKS & COMPARISONS
Remarks: This species is likely conspecific with the ?Pygaster sp. described by Smith & Rader (2009) from the Glen Rose of Comal County.
Comparisons:
Plate: PySp-10
Series: Lower Cretaceous Group: Trinity Formation: Glen rose
Locale: Startzville County: Comal Stage: Albian
Length: 20.6 mm Width: 24.9 mm Height: 7.6 mm
Collector: Ed Elliott
Specimen in photograph NPL 94356
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
FIGURED SPECIMEN INFO:
Specimen: NPL 94356.
Locality: Startzville, Comal County, Texas.
Stratigraphy: Glen Rose Formation, Trinity Group.
SYNONYMY
- ?Pygaster sp. Smith & Rader, 2009 (p. 42, Fig. 20)
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Order: Pygasteroida Durham & Melville, 1957
Family: Pygasteridae Lambert, 1900
Genus: PYGASTER L. Agassiz, 1836
Species: Pygaster sp.
TYPE SPECIES: Clypeus semisulcatus Phillips, 1829
DIAGNOSIS
A Pygaster from the Glen Rose Formation characterized by a test that is much wider than tall (transverse oval) with a squat profile. The periproct is teardrop-shaped and continuous with the apical system.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Trinity
Formations: Glen Rose Formation.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Comal.
Abundance: Rare; four specimens found (one complete).
DESCRIPTION
TOP: Length, width, height: 20.6 mm L × 24.9 mm W × 7.6 mm H. Top shape: Transverse oval (wider than long). Top domed: Apical system positioned anterior of center.
SIDE: Ambitus: Positioned 40% of height from the adoral side. Side shape: Inflated with rounded sides.
BOTTOM: Bottom shape: Adoral surface concave.
AMB: Amb shape: Lanceolate; pointed at apical system, widest at margin. Amb arrangement: Secondary tubercles present in perradial area starting 1/3 above and 1/3 below the margin. Width: Interambulacra are 2.5 times wider than ambulacra at the margin. Plating: Trigeminate throughout.
PORE PAIRS: Arrangement: Uniserial. Shape: Small and round.
TUBERCLES: Primary Perforated: Yes.
Primary Crenulate: Yes.
Ambulacral Tubercles: A row of primary tubercles runs next to the pore pairs aborally.
Interambulacral Tubercles: Aborally, two rows of primary tubercles run the entire length. Adorally, six rows of primary tubercles and two rows of secondary tubercles (starting just below margin) are present. Rows of secondary tubercles run 1/2 to 1/3 above and below the margin on either side of the primaries.
Areolas: Sunken. Bosses: Protruding. Scrobicular Tubercles: Surround primary and secondary tubercles.
GRANULES: See Tubercles.
FASCIOLE: Absent in Pygasteridae.
INTERAMB: Shape: Plates slightly wider than tall.
APICAL SYSTEM: Location: Anterior of center. Condition: Missing in specimen; joined with periproct creating a keyhole pattern.
PERIPROCT (ANUS): Shape: Large, teardrop shaped; length almost 1.5 times the width. Location: Aboral; no plates present between it and the apical system (confluent).
PERISTOME (MOUTH): Size: Small (1/3 size of test); larger than apical system. Shape: Oval. Lip: Notches small and faint.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: One complete crushed specimen (NPL 94356) and plates from three other specimens (including NPL 94357). Found by Ed Elliott.
ETYMOLOGY
[Not Applicable; open nomenclature].
REMARKS & COMPARISONS
Remarks: This species is likely conspecific with the ?Pygaster sp. described by Smith & Rader (2009) from the Glen Rose of Comal County.
Comparisons:
- Pygaster borachoensis: Another known Texas Pygaster (Upper Cretaceous/Cenomanian).
- Pygaster ornatus: Pygaster sp. has a wider periproct that reaches closer to the margin, and the notches are much smaller.
- Pygaster gresslyi, P. truncatus, P. macrostoma, P. laganoides: The Texas specimen has fewer aboral tubercles than these species.
