Maretia arguta (Clark, 1915)
Plate: MaAr-10
Series: Middle Eocene Group: Middle Claiborne Formation: Weches
Locale: San Augustine County: San Augustine Stage: Lutetian
Length: 42.0 mm Width: 39.2 mm Height: 15.7 mm
Specimen in photos: Collection of Melvin Noble
Repository: Private Collection
HOLOTYPE INFO:
Holotype: USNM 164666 (USGS Collection).
Locality: USGS 6462, 1 mile east of Enterprise, Clarke County, Mississippi.
Stratigraphy: Winona Sand (Middle Eocene).
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: Maretiidae Lambert, 1905
Genus: MARETIA Gray, 1855
Species: Maretia arguta (Clark, 1915)
TYPE SPECIES: Spatangus planulatus Lamarck, 1816
DIAGNOSIS
Test low, angularly cordate, and emarginate in front; posterior rostrated and truncated. Paired petals are straight and short. Large scrobiculate tubercles are confined to the dorsal anterior and anterolateral interambulacra. Distinguished from Hemipatagus by the absence of a peripetalous fasciole (Cooke, 1942).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Claiborne (Middle)
Formations: Weches Formation (Texas); Winona Sand (Mississippi).
Stratigraphic Units: Paleogene, Middle Eocene.
Counties: San Augustine (Texas); Clarke (Mississippi).
Abundance: Rare in Texas.
DESCRIPTION
TOP: Length, width, height: 42.0 mm L × 39.2 mm W × 15.7 mm H.
Top shape: Angularly cordate; emarginate in front, truncated on anterolateral and posterolateral margins. Widest in front of the center (Cooke, 1942).
Top domed: Upper surface rather low.
SIDE: Side shape: Highest behind; rostrate (beaked) posteriorly. Margin subacute (Cooke, 1942).
BOTTOM: Bottom shape: Lower surface nearly flat.
AMB: Amb shape: Anterior ambulacrum (III) not petaloid; slightly depressed, forming a wide V-shaped emargination in front.
Amb arrangement: Paired petals straight, rather short, extending little more than halfway to the margin. Anterior pair diverges at ~150°; posterior pair diverges at ~40°. Interporiferous zones nearly equal to the poriferous zones, tapering slightly at each end (Cooke, 1942).
PORE PAIRS: Shape: Pores oval.
Arrangement: Conjugate.
TUBERCLES: Primary Perforated: Yes.
Primary Crenulate: Yes.
Distribution: Large scrobiculate tubercles are confined to the anterior interambulacra and the anterior half of the posterior paired interambulacra on the upper surface. Smaller tubercles present on the lower surface (Cooke, 1942).
GRANULES: See Tubercles.
FASCIOLE: Subanal: Nearly obliterated in type material, but bilobate structure implied by genus.
Peripetalous: Absent (diagnostic of Maretia).
APICAL SYSTEM: Location: At the anterior third.
Genital pores: Four genital pores.
Type: Apparently ethmolytic (Cooke, 1942).
PERIPROCT (ANUS): Shape: Transversely oval.
Location: Terminal, vertical; on the posterior truncation (Cooke, 1942).
PERISTOME (MOUTH): Shape: Transverse; ends rounded.
Location: Farther forward than the apical system.
Lip: Labrum prominent (Cooke, 1942).
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: One specimen from the Collection of Melvin Noble.
ETYMOLOGY
From the Latin argutus (sharp, clear, or defined), likely referring to the angular/acute margin or the distinct tuberculation.
REMARKS & COMPARISONS
Remarks: Clark (1915) originally assigned this species to Hemipatagus. Cooke (1942) transferred it to Maretia based on the distribution of large dorsal tubercles and the apparent absence of a peripetalous fasciole.
Comparisons:
Maretia subrostrata: M. arguta is similar to the Eocene M. subrostrata (Hemipatagus subrostratus Clark) but is distinguished by the specific arrangement of the large tubercles and petal divergence angles.
Plate: MaAr-10
Series: Middle Eocene Group: Middle Claiborne Formation: Weches
Locale: San Augustine County: San Augustine Stage: Lutetian
Length: 42.0 mm Width: 39.2 mm Height: 15.7 mm
Specimen in photos: Collection of Melvin Noble
Repository: Private Collection
HOLOTYPE INFO:
Holotype: USNM 164666 (USGS Collection).
Locality: USGS 6462, 1 mile east of Enterprise, Clarke County, Mississippi.
Stratigraphy: Winona Sand (Middle Eocene).
SYNONYMY
- Hemipatagus argutus Clark, 1915
- Maretia arguta (Clark) Cooke, 1942
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: Maretiidae Lambert, 1905
Genus: MARETIA Gray, 1855
Species: Maretia arguta (Clark, 1915)
TYPE SPECIES: Spatangus planulatus Lamarck, 1816
DIAGNOSIS
Test low, angularly cordate, and emarginate in front; posterior rostrated and truncated. Paired petals are straight and short. Large scrobiculate tubercles are confined to the dorsal anterior and anterolateral interambulacra. Distinguished from Hemipatagus by the absence of a peripetalous fasciole (Cooke, 1942).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Claiborne (Middle)
Formations: Weches Formation (Texas); Winona Sand (Mississippi).
Stratigraphic Units: Paleogene, Middle Eocene.
Counties: San Augustine (Texas); Clarke (Mississippi).
Abundance: Rare in Texas.
DESCRIPTION
TOP: Length, width, height: 42.0 mm L × 39.2 mm W × 15.7 mm H.
Top shape: Angularly cordate; emarginate in front, truncated on anterolateral and posterolateral margins. Widest in front of the center (Cooke, 1942).
Top domed: Upper surface rather low.
SIDE: Side shape: Highest behind; rostrate (beaked) posteriorly. Margin subacute (Cooke, 1942).
BOTTOM: Bottom shape: Lower surface nearly flat.
AMB: Amb shape: Anterior ambulacrum (III) not petaloid; slightly depressed, forming a wide V-shaped emargination in front.
Amb arrangement: Paired petals straight, rather short, extending little more than halfway to the margin. Anterior pair diverges at ~150°; posterior pair diverges at ~40°. Interporiferous zones nearly equal to the poriferous zones, tapering slightly at each end (Cooke, 1942).
PORE PAIRS: Shape: Pores oval.
Arrangement: Conjugate.
TUBERCLES: Primary Perforated: Yes.
Primary Crenulate: Yes.
Distribution: Large scrobiculate tubercles are confined to the anterior interambulacra and the anterior half of the posterior paired interambulacra on the upper surface. Smaller tubercles present on the lower surface (Cooke, 1942).
GRANULES: See Tubercles.
FASCIOLE: Subanal: Nearly obliterated in type material, but bilobate structure implied by genus.
Peripetalous: Absent (diagnostic of Maretia).
APICAL SYSTEM: Location: At the anterior third.
Genital pores: Four genital pores.
Type: Apparently ethmolytic (Cooke, 1942).
PERIPROCT (ANUS): Shape: Transversely oval.
Location: Terminal, vertical; on the posterior truncation (Cooke, 1942).
PERISTOME (MOUTH): Shape: Transverse; ends rounded.
Location: Farther forward than the apical system.
Lip: Labrum prominent (Cooke, 1942).
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: One specimen from the Collection of Melvin Noble.
ETYMOLOGY
From the Latin argutus (sharp, clear, or defined), likely referring to the angular/acute margin or the distinct tuberculation.
REMARKS & COMPARISONS
Remarks: Clark (1915) originally assigned this species to Hemipatagus. Cooke (1942) transferred it to Maretia based on the distribution of large dorsal tubercles and the apparent absence of a peripetalous fasciole.
Comparisons:
Maretia subrostrata: M. arguta is similar to the Eocene M. subrostrata (Hemipatagus subrostratus Clark) but is distinguished by the specific arrangement of the large tubercles and petal divergence angles.
