Holectypus cragini Clark, 1915
Plate: HoCr-10
Series: Jurassic, Upper Series Formation: Malone
Locale: Malone Mountains County: Hudspeth Stage: Tithonian
Length: 27.2 mm Height: 7.8 mm
Specimen in photo: Collection of Frank Crane
HOLOTYPE INFO:
Holotype: USNM 31189 (United States National Museum).
Locality: Malone Mountains, Hudspeth County, Texas.
Stratigraphy: Malone Formation (Upper Jurassic).
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Holectypoida Ducrotay de Blainville, 1825
Order: Holectypoida Ducrotay de Blainville, 1825
Family: Holectypidae Lambert, 1900
Genus: HOLECTYPUS Desor, 1842
Species: Holectypus cragini Clark, 1915
TYPE SPECIES: Echinites depressus Leske, 1778
DIAGNOSIS
Test subcircular and subconical. Ambulacra narrow and straight; interambulacra wide. Distinct from the Cretaceous H. planatus by its Jurassic geologic position and pyramidal profile (Clark, 1915).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: (Upper Series)
Formations: Malone Formation
Stratigraphic Units: Upper Jurassic, Tithonian
Counties: Hudspeth
Abundance: Rare.
DESCRIPTION
TOP: Length, width, height: 27.2 mm L × 7.8 mm H. Top shape: Subcircular (Clark, 1915); circular.
Top domed: Pyramidal with a raised dome in the center. Size Range: up to 36 mm.
SIDE: Ambitus: Relatively sharp (Clark, 1915); positioned near the bottom.
Side shape: Subconical/Subcorneal (Clark, 1915); pyramidal.
BOTTOM: Bottom shape: Flat undersurface indicated by sharp ambitus (Clark, 1915); concave.
AMB: Amb shape: Narrow and straight (Clark, 1915); lanceolate.
Amb arrangement: Widest at the ambitus.
PORE PAIRS: Arrangement: Straight and narrow (Clark, 1915).
Shape: Obliquely round and offset; very tight on the aboral surface.
TUBERCLES: Primary Perforated: Finely perforated.
Primary Crenulate: Yes (Characteristic of genus).
Distribution: Tubercles are small and cover the greater portion of the plates (Clark, 1915). Largest tubercles are found on the adoral surface near the ambitus and on the entire aboral surface. Several rows of tubercles present in ambulacra (Clark, 1915).
INTERAMB: Width: Wide (Clark, 1915); twice the size of ambulacra.
APICAL SYSTEM: Location: At apex.
Size: Small (Clark, 1915).
Condition: Imperfect/indistinct in type material; tight in studied specimen.
PERIPROCT (ANUS): Shape: Oval.
Location: Oral surface.
Visibility: Cannot be seen from above.
PERISTOME (MOUTH): Shape: Ovate.
Size: Takes up 1/3 of the bottom surface.
Sunken: Sunken.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Specimen from the collection of Frank Crane. Original description by Clark was based on a fragmentary specimen collected by Cragin.
ETYMOLOGY
Named in honor of F.W. Cragin, who first surveyed the Malone Mountains and collected the original material.
REMARKS & COMPARISONS
Remarks: Clark (1915) noted that while this species resembles the Cretaceous H. planatus in general outline, its much earlier geologic position (Jurassic) necessitates its separation as an independent species.
Comparisons:
Remarks: (01-2025) The Holotype is incomplete and shows very little details.
Plate: HoCr-10
Series: Jurassic, Upper Series Formation: Malone
Locale: Malone Mountains County: Hudspeth Stage: Tithonian
Length: 27.2 mm Height: 7.8 mm
Specimen in photo: Collection of Frank Crane
HOLOTYPE INFO:
Holotype: USNM 31189 (United States National Museum).
Locality: Malone Mountains, Hudspeth County, Texas.
Stratigraphy: Malone Formation (Upper Jurassic).
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Holectypoida Ducrotay de Blainville, 1825
Order: Holectypoida Ducrotay de Blainville, 1825
Family: Holectypidae Lambert, 1900
Genus: HOLECTYPUS Desor, 1842
Species: Holectypus cragini Clark, 1915
TYPE SPECIES: Echinites depressus Leske, 1778
DIAGNOSIS
Test subcircular and subconical. Ambulacra narrow and straight; interambulacra wide. Distinct from the Cretaceous H. planatus by its Jurassic geologic position and pyramidal profile (Clark, 1915).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: (Upper Series)
Formations: Malone Formation
Stratigraphic Units: Upper Jurassic, Tithonian
Counties: Hudspeth
Abundance: Rare.
DESCRIPTION
TOP: Length, width, height: 27.2 mm L × 7.8 mm H. Top shape: Subcircular (Clark, 1915); circular.
Top domed: Pyramidal with a raised dome in the center. Size Range: up to 36 mm.
SIDE: Ambitus: Relatively sharp (Clark, 1915); positioned near the bottom.
Side shape: Subconical/Subcorneal (Clark, 1915); pyramidal.
BOTTOM: Bottom shape: Flat undersurface indicated by sharp ambitus (Clark, 1915); concave.
AMB: Amb shape: Narrow and straight (Clark, 1915); lanceolate.
Amb arrangement: Widest at the ambitus.
PORE PAIRS: Arrangement: Straight and narrow (Clark, 1915).
Shape: Obliquely round and offset; very tight on the aboral surface.
TUBERCLES: Primary Perforated: Finely perforated.
Primary Crenulate: Yes (Characteristic of genus).
Distribution: Tubercles are small and cover the greater portion of the plates (Clark, 1915). Largest tubercles are found on the adoral surface near the ambitus and on the entire aboral surface. Several rows of tubercles present in ambulacra (Clark, 1915).
INTERAMB: Width: Wide (Clark, 1915); twice the size of ambulacra.
APICAL SYSTEM: Location: At apex.
Size: Small (Clark, 1915).
Condition: Imperfect/indistinct in type material; tight in studied specimen.
PERIPROCT (ANUS): Shape: Oval.
Location: Oral surface.
Visibility: Cannot be seen from above.
PERISTOME (MOUTH): Shape: Ovate.
Size: Takes up 1/3 of the bottom surface.
Sunken: Sunken.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Specimen from the collection of Frank Crane. Original description by Clark was based on a fragmentary specimen collected by Cragin.
ETYMOLOGY
Named in honor of F.W. Cragin, who first surveyed the Malone Mountains and collected the original material.
REMARKS & COMPARISONS
Remarks: Clark (1915) noted that while this species resembles the Cretaceous H. planatus in general outline, its much earlier geologic position (Jurassic) necessitates its separation as an independent species.
Comparisons:
- H. planatus: H. cragini is similar in outline but separated by stratigraphy.
- H. peali: Clark (1915) states H. cragini is "wholly unlike H. peali in form."
Remarks: (01-2025) The Holotype is incomplete and shows very little details.
