Macraster solitariensis Smiser, 1936
Plate: MaSo-10
Series: Lower Cretaceous Group: Trinity Formation: Glen Rose
Locale: Solitario Rim County: Brewster Stage: Albian
Length: 38.6 mm Width: 41.0 mm Height: 24.1 mm
Specimen in photos: BEG 21271 Holotype
University of Texas Non-vertebrate Paleo. Lab.
HOLOTYPE INFO:
Holotype: BEG 21271 (Smiser, 1936)
Locality: Solitario Rim, west side of the Solitario, Brewster County, Texas.
Stratigraphy: Originally identified as "Washita limestone" by Smiser (1936); re-assigned to Glen Rose (Trinity) in current data.
SYNONYMY
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Atelostomata Zittel, 1879
Order: Spatangoida L. Agassiz, 1840
Family: Macrasteridae Lambert, 1920
Genus: MACRASTER Roemer, 1888
Species: Macraster solitariensis Smiser, 1936
TYPE SPECIES: Macraster texanus Roemer, 1888
DIAGNOSIS
Test cordate, inflated, and broader than long. Distinguished by paired ambulacra that are superficial (flush with the test surface) and a sunken unpaired ambulacrum. The posterior face is vertically truncated (Smiser, 1936).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Trinity (per input); Washita (per Smiser, 1936).
Formations: Glen Rose Formation.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Brewster.
Abundance: Rare.
DESCRIPTION
TOP: Length, width, height: 38.6 mm L × 41.0 mm W × 24.1 mm H.
Top shape: Cordate with a very angular margin; wider than tall (Smiser, 1936). Anterior margin is deeply notched by the sulcus.
Top domed: Apex positioned at the posterior third (1/3 from posterior end).
SIDE: Ambitus: Positioned about 38% of height from the base.
Side shape: Inflated.
Profile: Posterior end is long and vertically truncated; anterior end is sloping.
BOTTOM: Bottom shape: Mostly flat; plastron slightly inflated.
AMB: Amb shape: All 5 ambulacra are of equal width. The unpaired ambulacrum (III) is deeply sunken; the paired ambulacra are superficial (flush), wide, slightly petaloid, and very open at the outer ends (Smiser, 1936).
Amb arrangement: Anterior paired ambulacra are slightly longer than the posterior pair and almost reach the margin.
PORE PAIRS: Arrangement: Unpaired ambulacrum pores are round.
Shape: Pores in paired ambulacra are slightly elongated.
TUBERCLES: Distribution: Small. Tuberculation and granulation are more pronounced on the adoral surface.
GRANULES: See Tubercles section.
FASCIOLE: Absent in Macraster.
APICAL SYSTEM: Condition: Mostly missing in the holotype.
Type: Ethmophract (Smiser, 1936).
PERIPROCT (ANUS): Shape: Small; longitudinally oval.
Location: Situated on the small truncated posterior end, slightly above the midpoint from the base (Smiser, 1936).
Visibility: Barely visible from above.
PERISTOME (MOUTH): Shape: Round to subpentagonal.
Size: Depressed; about equal in size to the periproct.
Lip: Labiate (Smiser, 1936).
Visibility: Barely visible from the anterior end.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Holotype BEG 21271 studied.
ETYMOLOGY
Named for the Solitario Rim, the locality in West Texas where the type was discovered.
REMARKS & COMPARISONS
Remarks: Smiser (1936) noted that M. solitariensis is closely related to M. aguilerae but differs in having superficial (flush) paired ambulacra, whereas aguilerae has sunken petals. Kamyabi Shadan et al. (2014) regard M. solitariensis as a synonym of Macraster roberti (Lambert & Thiéry, 1924), interpreting the variations in test shape and petal depth as ecophenotypic traits of a single variable species.
Plate: MaSo-10
Series: Lower Cretaceous Group: Trinity Formation: Glen Rose
Locale: Solitario Rim County: Brewster Stage: Albian
Length: 38.6 mm Width: 41.0 mm Height: 24.1 mm
Specimen in photos: BEG 21271 Holotype
University of Texas Non-vertebrate Paleo. Lab.
HOLOTYPE INFO:
Holotype: BEG 21271 (Smiser, 1936)
Locality: Solitario Rim, west side of the Solitario, Brewster County, Texas.
Stratigraphy: Originally identified as "Washita limestone" by Smiser (1936); re-assigned to Glen Rose (Trinity) in current data.
SYNONYMY
- Macraster roberti Lambert & Thiéry, 1924 (fide Kamyabi Shadan et al., 2014)
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Atelostomata Zittel, 1879
Order: Spatangoida L. Agassiz, 1840
Family: Macrasteridae Lambert, 1920
Genus: MACRASTER Roemer, 1888
Species: Macraster solitariensis Smiser, 1936
TYPE SPECIES: Macraster texanus Roemer, 1888
DIAGNOSIS
Test cordate, inflated, and broader than long. Distinguished by paired ambulacra that are superficial (flush with the test surface) and a sunken unpaired ambulacrum. The posterior face is vertically truncated (Smiser, 1936).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Trinity (per input); Washita (per Smiser, 1936).
Formations: Glen Rose Formation.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Brewster.
Abundance: Rare.
DESCRIPTION
TOP: Length, width, height: 38.6 mm L × 41.0 mm W × 24.1 mm H.
Top shape: Cordate with a very angular margin; wider than tall (Smiser, 1936). Anterior margin is deeply notched by the sulcus.
Top domed: Apex positioned at the posterior third (1/3 from posterior end).
SIDE: Ambitus: Positioned about 38% of height from the base.
Side shape: Inflated.
Profile: Posterior end is long and vertically truncated; anterior end is sloping.
BOTTOM: Bottom shape: Mostly flat; plastron slightly inflated.
AMB: Amb shape: All 5 ambulacra are of equal width. The unpaired ambulacrum (III) is deeply sunken; the paired ambulacra are superficial (flush), wide, slightly petaloid, and very open at the outer ends (Smiser, 1936).
Amb arrangement: Anterior paired ambulacra are slightly longer than the posterior pair and almost reach the margin.
PORE PAIRS: Arrangement: Unpaired ambulacrum pores are round.
Shape: Pores in paired ambulacra are slightly elongated.
TUBERCLES: Distribution: Small. Tuberculation and granulation are more pronounced on the adoral surface.
GRANULES: See Tubercles section.
FASCIOLE: Absent in Macraster.
APICAL SYSTEM: Condition: Mostly missing in the holotype.
Type: Ethmophract (Smiser, 1936).
PERIPROCT (ANUS): Shape: Small; longitudinally oval.
Location: Situated on the small truncated posterior end, slightly above the midpoint from the base (Smiser, 1936).
Visibility: Barely visible from above.
PERISTOME (MOUTH): Shape: Round to subpentagonal.
Size: Depressed; about equal in size to the periproct.
Lip: Labiate (Smiser, 1936).
Visibility: Barely visible from the anterior end.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Holotype BEG 21271 studied.
ETYMOLOGY
Named for the Solitario Rim, the locality in West Texas where the type was discovered.
REMARKS & COMPARISONS
Remarks: Smiser (1936) noted that M. solitariensis is closely related to M. aguilerae but differs in having superficial (flush) paired ambulacra, whereas aguilerae has sunken petals. Kamyabi Shadan et al. (2014) regard M. solitariensis as a synonym of Macraster roberti (Lambert & Thiéry, 1924), interpreting the variations in test shape and petal depth as ecophenotypic traits of a single variable species.
