Holaster comanchesi Marcou, 1858
Plate: HoCo-10
Series: Lower Cretaceous Group: Washita Formation: Duck Creek
Locale: Preston County: Grayson Stage: Albian
Length: 55.8 mm Width: 49.9 mm Height: 38.3 mm
Specimen in photo: BEG 34030 Plaster Cast of Holotype
University of Texas Non-vertebrate Paleo. Lab.
Plate: HoCo-20
Series: Lower Cretaceous Group: Washita Formation: Weno
Locale: Lake Cleburne County: Johnson Stage: Albian
Length: 20.4 mm Width: 17.7 mm Height: 16.2 mm
Specimen in photo: Collection of Frank Crane
HOLOTYPE INFO:
Holotype: Originally in the Marcou Collection (British Museum of Natural History, London). BEG 34030 is a plastotype (cast).
Locality: Preston, Grayson County, Texas (Marcou, 1858).
Stratigraphy: "Limestone of the Cretaceous rocks" (Duck Creek Formation, Washita Group).
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Atelostomata Zittel, 1879
Order: Holasteroida Durham, 1957
Family: Holasteridae Pictet, 1857
Genus: HOLASTER L. Agassiz, 1836
Species: Holaster comanchesi Marcou, 1858
TYPE SPECIES: Spatangus nodulosus Goldfuss, 1829
DIAGNOSIS
Shell oval, cordate, and very convex; top slightly pointed at the apical disc which is anterior of center. Distinguished from H. simplex by its straight (not flexuous) ambulacra and more pointed apical profile (Marcou, 1858).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Duck Creek, Weno
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Grayson, Johnson
DESCRIPTION
TOP: Length, width, height: 55.8 mm L × 49.9 mm W × 38.3 mm H.
Top shape: Oval, cordate; longer than wide. Enlarged and sinuous in front, acuminated (tapering) at the opposite side (Marcou, 1858).
Top domed: Very convex and slightly pointed, the point corresponding to the apical disc (Marcou, 1858).
SIDE: Side shape: Very convex. Anterior sinus straight, shallow, and rounded, disappearing before reaching the apical disc.
Profile: Apex placed a little in advance of the middle of the total length (Marcou, 1858).
BOTTOM: Bottom shape: Entirely flat, excepting a slight elevation towards the rear and a little depression in front/sides of the mouth (Marcou, 1858).
AMB: Amb shape: Straight, regularly radiate, and linear-lanceolate. They extend to the outline of the shell, increasing gradually in width to the inferior margin (Marcou, 1858).
Amb arrangement: Unpaired ambulacrum (III) located in a shallow, rounded anterior sinus.
INTERAMB: Shape: Interambulacral spaces feature rather large tubercles near the apex (Marcou, 1858).
PORE PAIRS: Shape: Transverse and oblong (Marcou, 1858).
TUBERCLES: Primary Perforated: Yes.
Primary Crenulate: Yes (set upon bosses with crenulated summits).
Distribution: Large tubercles near the apex in interambulacral spaces; tubercles are very numerous on the underside of the shell (Marcou, 1858).
GRANULES: Not explicitly described by Marcou, implied by "numerous tubercles".
FASCIOLE: Not described by Marcou; Holaster typically possesses a subanal fasciole, though often lost in preservation.
APICAL SYSTEM: Location: Anterior of center (a little in advance of the middle).
Condition: Very indistinct in holotype; not described (Marcou, 1858). Elongate type characteristic of Holasterids.
PERIPROCT (ANUS): Shape: Vertically elliptical orifice (Marcou, 1858).
Location: Obtusely truncate anal extremity; placed at or a little lower than half the height of the test (Marcou, 1858).
PERISTOME (MOUTH): Shape: Large, transversely oblong (Marcou, 1858).
Location: Placed near the anterior edge.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION:
ETYMOLOGY
Named for the Comanche Indians or the Comanche Series of Texas.
REMARKS & COMPARISONS
Remarks: Cooke (1946) regarded Holaster comanchesi as a synonym of the widespread species Holaster laevis (Brongniart). I do not agree with this synonym. This is a rare species and the height and pointed sharp profile is very distinctive.
Comparisons:
Plate: HoCo-10
Series: Lower Cretaceous Group: Washita Formation: Duck Creek
Locale: Preston County: Grayson Stage: Albian
Length: 55.8 mm Width: 49.9 mm Height: 38.3 mm
Specimen in photo: BEG 34030 Plaster Cast of Holotype
University of Texas Non-vertebrate Paleo. Lab.
Plate: HoCo-20
Series: Lower Cretaceous Group: Washita Formation: Weno
Locale: Lake Cleburne County: Johnson Stage: Albian
Length: 20.4 mm Width: 17.7 mm Height: 16.2 mm
Specimen in photo: Collection of Frank Crane
HOLOTYPE INFO:
Holotype: Originally in the Marcou Collection (British Museum of Natural History, London). BEG 34030 is a plastotype (cast).
Locality: Preston, Grayson County, Texas (Marcou, 1858).
Stratigraphy: "Limestone of the Cretaceous rocks" (Duck Creek Formation, Washita Group).
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Atelostomata Zittel, 1879
Order: Holasteroida Durham, 1957
Family: Holasteridae Pictet, 1857
Genus: HOLASTER L. Agassiz, 1836
Species: Holaster comanchesi Marcou, 1858
TYPE SPECIES: Spatangus nodulosus Goldfuss, 1829
DIAGNOSIS
Shell oval, cordate, and very convex; top slightly pointed at the apical disc which is anterior of center. Distinguished from H. simplex by its straight (not flexuous) ambulacra and more pointed apical profile (Marcou, 1858).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Duck Creek, Weno
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Grayson, Johnson
DESCRIPTION
TOP: Length, width, height: 55.8 mm L × 49.9 mm W × 38.3 mm H.
Top shape: Oval, cordate; longer than wide. Enlarged and sinuous in front, acuminated (tapering) at the opposite side (Marcou, 1858).
Top domed: Very convex and slightly pointed, the point corresponding to the apical disc (Marcou, 1858).
SIDE: Side shape: Very convex. Anterior sinus straight, shallow, and rounded, disappearing before reaching the apical disc.
Profile: Apex placed a little in advance of the middle of the total length (Marcou, 1858).
BOTTOM: Bottom shape: Entirely flat, excepting a slight elevation towards the rear and a little depression in front/sides of the mouth (Marcou, 1858).
AMB: Amb shape: Straight, regularly radiate, and linear-lanceolate. They extend to the outline of the shell, increasing gradually in width to the inferior margin (Marcou, 1858).
Amb arrangement: Unpaired ambulacrum (III) located in a shallow, rounded anterior sinus.
INTERAMB: Shape: Interambulacral spaces feature rather large tubercles near the apex (Marcou, 1858).
PORE PAIRS: Shape: Transverse and oblong (Marcou, 1858).
TUBERCLES: Primary Perforated: Yes.
Primary Crenulate: Yes (set upon bosses with crenulated summits).
Distribution: Large tubercles near the apex in interambulacral spaces; tubercles are very numerous on the underside of the shell (Marcou, 1858).
GRANULES: Not explicitly described by Marcou, implied by "numerous tubercles".
FASCIOLE: Not described by Marcou; Holaster typically possesses a subanal fasciole, though often lost in preservation.
APICAL SYSTEM: Location: Anterior of center (a little in advance of the middle).
Condition: Very indistinct in holotype; not described (Marcou, 1858). Elongate type characteristic of Holasterids.
PERIPROCT (ANUS): Shape: Vertically elliptical orifice (Marcou, 1858).
Location: Obtusely truncate anal extremity; placed at or a little lower than half the height of the test (Marcou, 1858).
PERISTOME (MOUTH): Shape: Large, transversely oblong (Marcou, 1858).
Location: Placed near the anterior edge.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION:
- Holotype (Cast): BEG 34030. Plaster cast of Marcou's original.
- Specimen 2: Collection of Frank Crane. Small specimen (20.4 mm).
ETYMOLOGY
Named for the Comanche Indians or the Comanche Series of Texas.
REMARKS & COMPARISONS
Remarks: Cooke (1946) regarded Holaster comanchesi as a synonym of the widespread species Holaster laevis (Brongniart). I do not agree with this synonym. This is a rare species and the height and pointed sharp profile is very distinctive.
Comparisons:
- H. simplex: Marcou (1858) distinguished H. comanchesi from H. simplex by its straight ambulacra (vs. flexuous in simplex) and its slightly pointed superior profile (vs. regularly rounded in simplex).
