Micraster uddeni Cooke, 1953
Plate: MiUd-10
Series: Upper Cretaceous Group: Austin Formation: Austin Chalk
Locale: Eagle Pass County: Maverick Stage: Santonian
Length: 55.5. mm Width: 57.6 mm Height: 31.1 mm
Specimen in Photo: Collection of Steven Crane
Repository: Private Collection
HOLOTYPE INFO:
Holotype: USNM 108380 (Cooke, 1953).
Locality: USGS 15570, Tequesquite Creek, 18 miles south of Uvalde, Maverick County, Texas.
Stratigraphy: Austin Chalk.
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: Micrasteridae Lambert, 1920
Genus: MICRASTER L. Agassiz, 1836
Species: Micraster uddeni Cooke, 1953
TYPE SPECIES: Spatangus coranguinum Leske, 1778
DIAGNOSIS
Test cordate, wider than long. Characterized by a deep, narrow anterior sulcus extending from apex to peristome. Anterior paired petals are twice as long as the posterior pair. Apical system is ethmophract. Subanal fasciole present (Cooke, 1953).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Austin
Formations: Austin Chalk.
Stratigraphic Units: Upper Cretaceous, Santonian.
Counties: Maverick.
Abundance: Rare.
DESCRIPTION
TOP: Length, width, height: 55.5 mm L × 57.6 mm W × 31.1 mm H.
Top shape: Cordate (Cooke, 1953).
Top domed: Deep narrow sulcus extending from the apex to the peristome.
SIDE: Side shape: Posterior truncation present.
AMB: Amb shape: Petals sunken and straight.
Amb arrangement: Anterior paired petals are twice as long as the posterior pair and slightly more widely spreading.
Unpaired Amb: Anterior ambulacrum pore zones are much narrower than the interporiferous zone.
PORE PAIRS: Shape: Pores of paired petals are elongate.
Arrangement: Poriferous zones of paired petals equal the interporiferous zones in width. Pores of the anterior unpaired ambulacrum are arranged en echelon (diagonal pairs), separated by a small bead (Cooke, 1953).
TUBERCLES: Not specified.
FASCIOLE: Subanal: Partly preserved in type material (Cooke, 1953). (Presence of subanal fasciole is diagnostic for Micraster).
APICAL SYSTEM: Location: Slightly posterior.
Type: Ethmophract (posterior ocular plates large and in contact).
Genital pores: Four genital pores (Cooke, 1953).
PERIPROCT (ANUS): Location: Terminal; situated about halfway up the posterior truncation (Cooke, 1953).
PERISTOME (MOUTH): Location: Far forward (Cooke, 1953).
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: One specimen studied from the Collection of Steven Crane.
ETYMOLOGY
Named in honor of Johan August Udden (1859–1932), distinguished geologist and Director of the Bureau of Economic Geology (University of Texas), who contributed significantly to the understanding of Texas stratigraphy.
REMARKS & COMPARISONS
Comparisons:
Plate: MiUd-10
Series: Upper Cretaceous Group: Austin Formation: Austin Chalk
Locale: Eagle Pass County: Maverick Stage: Santonian
Length: 55.5. mm Width: 57.6 mm Height: 31.1 mm
Specimen in Photo: Collection of Steven Crane
Repository: Private Collection
HOLOTYPE INFO:
Holotype: USNM 108380 (Cooke, 1953).
Locality: USGS 15570, Tequesquite Creek, 18 miles south of Uvalde, Maverick County, Texas.
Stratigraphy: Austin Chalk.
SYNONYMY
- Micraster uddeni Cooke, 1953
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: Micrasteridae Lambert, 1920
Genus: MICRASTER L. Agassiz, 1836
Species: Micraster uddeni Cooke, 1953
TYPE SPECIES: Spatangus coranguinum Leske, 1778
DIAGNOSIS
Test cordate, wider than long. Characterized by a deep, narrow anterior sulcus extending from apex to peristome. Anterior paired petals are twice as long as the posterior pair. Apical system is ethmophract. Subanal fasciole present (Cooke, 1953).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Austin
Formations: Austin Chalk.
Stratigraphic Units: Upper Cretaceous, Santonian.
Counties: Maverick.
Abundance: Rare.
DESCRIPTION
TOP: Length, width, height: 55.5 mm L × 57.6 mm W × 31.1 mm H.
Top shape: Cordate (Cooke, 1953).
Top domed: Deep narrow sulcus extending from the apex to the peristome.
SIDE: Side shape: Posterior truncation present.
AMB: Amb shape: Petals sunken and straight.
Amb arrangement: Anterior paired petals are twice as long as the posterior pair and slightly more widely spreading.
Unpaired Amb: Anterior ambulacrum pore zones are much narrower than the interporiferous zone.
PORE PAIRS: Shape: Pores of paired petals are elongate.
Arrangement: Poriferous zones of paired petals equal the interporiferous zones in width. Pores of the anterior unpaired ambulacrum are arranged en echelon (diagonal pairs), separated by a small bead (Cooke, 1953).
TUBERCLES: Not specified.
FASCIOLE: Subanal: Partly preserved in type material (Cooke, 1953). (Presence of subanal fasciole is diagnostic for Micraster).
APICAL SYSTEM: Location: Slightly posterior.
Type: Ethmophract (posterior ocular plates large and in contact).
Genital pores: Four genital pores (Cooke, 1953).
PERIPROCT (ANUS): Location: Terminal; situated about halfway up the posterior truncation (Cooke, 1953).
PERISTOME (MOUTH): Location: Far forward (Cooke, 1953).
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: One specimen studied from the Collection of Steven Crane.
ETYMOLOGY
Named in honor of Johan August Udden (1859–1932), distinguished geologist and Director of the Bureau of Economic Geology (University of Texas), who contributed significantly to the understanding of Texas stratigraphy.
REMARKS & COMPARISONS
Comparisons:
- Micraster coranguinum: M. uddeni is flatter and has longer petals than M. coranguinum (Leske).
- Micraster americanus: M. uddeni is proportionately shorter and wider than M. americanus (Stephenson), and its posterior petals are shorter (Cooke, 1953).
