Macraster aguilerae (Bose, 1910)
Plate: MaAq-10
Series: Lower Cretaceous Group: Washita Formation: Fort Worth
Locale: Fort Worth County: Tarrant Stage: Albian
Length: 64.0 mm Width: 63.9 mm Height: 39.0 mm
Specimen in photos: BEG 21498 Hypotype
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: Originally described by Böse (1910). Repository: Instituto Geológico de México (IGM).
Locality: Subdivision 5 (Fort Worth Formation equivalent), Cerro de Muleros, Chihuahua, Mexico/Texas border.
Stratigraphy: Washita Group.
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 aguilerae (Böse, 1910)
TYPE SPECIES: Macraster texanus Roemer, 1888
DIAGNOSIS
A large Macraster characterized by a decidedly rounded, non-angular contour. It is proportionately broader and shorter than M. elegans. Ambulacra are narrow, flexuous near the ambitus, and sunken in shallow grooves.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Fort Worth Limestone.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Tarrant, El Paso (Cerro de Muleros).
Abundance: Rare; Adkins noted two individuals.
DESCRIPTION
TOP: Length, width, height: 64.0 mm L × 63.9 mm W × 39.0 mm H.
Top shape: Contour decidedly rounded and non-angular (Adkins, 1920). Widest point is just anterior to the apical system.
Top domed: Rounded.
SIDE: Side shape: Longitudinal section is less tall and more evenly rounded posteriorly than M. elegans.
Profile: Slightly taller and longer from the apical system back compared to the type, likely due to crushing (Adkins, 1920).
AMB: Amb shape: Narrower and sunken in much shallower grooves than in M. elegans.
Amb arrangement: Anterolateral ambulacra diverge at a greater angle than the type. Ambulacra are flexuous near the ambitus.
TUBERCLES: Not detailed; implied fine granulation typical of genus.
FASCIOLE: Presence: No fascioles are visible (Adkins, 1920). (Absence of fascioles is a key generic trait distinguishing Macraster from Hemiaster).
APICAL SYSTEM: Size: Madreporite is smaller than in M. elegans or M. texanus (Adkins, 1920).
PERIPROCT (ANUS): Shape: Pointed at both ends (in smaller specimen).
Location: Situated lower than in typical M. elegans from Fort Worth, but higher than in examples figured by Clark (Adkins, 1920).
PERISTOME (MOUTH): Small, partially hidden with matrix.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Hypotype BEG 21498. This individual is noted to have suffered a small amount of end-wise crushing (Adkins, 1920).
ETYMOLOGY
Named in honor of José Guadalupe Aguilera (1857–1941), a prominent Mexican geologist and director of the Instituto Geológico de México.
REMARKS & COMPARISONS
Remarks: Cooke (1946) considers M. aguilerae to be a synonym of the variable Macraster elegans (Shumard). Adkins (1920) noted that the Hemiaster elegans group in the Fort Worth Limestone was in an "unsatisfactory taxonomic condition" and likely contained more than one species, leading him to retain aguilerae for these rounded forms.
Comparisons:
Plate: MaAq-10
Series: Lower Cretaceous Group: Washita Formation: Fort Worth
Locale: Fort Worth County: Tarrant Stage: Albian
Length: 64.0 mm Width: 63.9 mm Height: 39.0 mm
Specimen in photos: BEG 21498 Hypotype
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: Originally described by Böse (1910). Repository: Instituto Geológico de México (IGM).
Locality: Subdivision 5 (Fort Worth Formation equivalent), Cerro de Muleros, Chihuahua, Mexico/Texas border.
Stratigraphy: Washita Group.
SYNONYMY
- Epiaster aguilerae Böse, 1910
- Macraster elegans (Shumard, 1853) (fide Cooke, 1946)
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 aguilerae (Böse, 1910)
TYPE SPECIES: Macraster texanus Roemer, 1888
DIAGNOSIS
A large Macraster characterized by a decidedly rounded, non-angular contour. It is proportionately broader and shorter than M. elegans. Ambulacra are narrow, flexuous near the ambitus, and sunken in shallow grooves.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Fort Worth Limestone.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Tarrant, El Paso (Cerro de Muleros).
Abundance: Rare; Adkins noted two individuals.
DESCRIPTION
TOP: Length, width, height: 64.0 mm L × 63.9 mm W × 39.0 mm H.
Top shape: Contour decidedly rounded and non-angular (Adkins, 1920). Widest point is just anterior to the apical system.
Top domed: Rounded.
SIDE: Side shape: Longitudinal section is less tall and more evenly rounded posteriorly than M. elegans.
Profile: Slightly taller and longer from the apical system back compared to the type, likely due to crushing (Adkins, 1920).
AMB: Amb shape: Narrower and sunken in much shallower grooves than in M. elegans.
Amb arrangement: Anterolateral ambulacra diverge at a greater angle than the type. Ambulacra are flexuous near the ambitus.
TUBERCLES: Not detailed; implied fine granulation typical of genus.
FASCIOLE: Presence: No fascioles are visible (Adkins, 1920). (Absence of fascioles is a key generic trait distinguishing Macraster from Hemiaster).
APICAL SYSTEM: Size: Madreporite is smaller than in M. elegans or M. texanus (Adkins, 1920).
PERIPROCT (ANUS): Shape: Pointed at both ends (in smaller specimen).
Location: Situated lower than in typical M. elegans from Fort Worth, but higher than in examples figured by Clark (Adkins, 1920).
PERISTOME (MOUTH): Small, partially hidden with matrix.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Hypotype BEG 21498. This individual is noted to have suffered a small amount of end-wise crushing (Adkins, 1920).
ETYMOLOGY
Named in honor of José Guadalupe Aguilera (1857–1941), a prominent Mexican geologist and director of the Instituto Geológico de México.
REMARKS & COMPARISONS
Remarks: Cooke (1946) considers M. aguilerae to be a synonym of the variable Macraster elegans (Shumard). Adkins (1920) noted that the Hemiaster elegans group in the Fort Worth Limestone was in an "unsatisfactory taxonomic condition" and likely contained more than one species, leading him to retain aguilerae for these rounded forms.
Comparisons:
- M. elegans: M. aguilerae is broader, shorter, and has a more rounded/less angular contour. The ambulacra are narrower and shallower. The posterior profile is more evenly rounded (less straight-sided) (Adkins, 1920).
- M. texanus: The madreporite in M. aguilerae is smaller than in M. texanus.
