Cidaris sp. Leske, 1778
Plate: CiSp-10
Series: Upper Cretaceous Group: Navarro Formation: Escondido
Locale: Sabinal County: Uvalde Stage: Maastrichtian
Length: 18.2 mm Width: 14.1 mm Height: 2.0 mm
Specimen in photo: U.S.N.M. 459580
Paleobiology Depart. NMNH, Smithsonian Institution Plates.
Plate: CiSp-20
Series: Upper Cretaceous Group: Navarro Formation: Escondido
Locale: Sabinal County: Uvalde
Length: 23.3 mm (longest) Width: 3.3 mm
Specimen in photo: U.S.N.M. 459580
Paleobiology Depart. NMNH, Smithsonian Institution Spines.
Systematic Paleontology
CLASS: ECHINOIDEA Leske, 1778
SUBCLASS: CIDAROIDEA Smith, 1984
ORDER: CIDAROIDA Claus, 1880
FAMILY: CIDARIDAE Gray, 1825
GENUS: CIDARIS Leske, 1778
SPECIES: Cidaris sp.
TYPE SPECIES: Echinus cidaris Linnaeus, 1758
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Navarro
Formations: Escondido Formation
Stratigraphic Units: Upper Cretaceous, Maastrichtian
Counties: Uvalde County
DESCRIPTION
(Note: The following morphological descriptions are based on the Family/Generic definition provided by Wright (1864-1882) and do not necessarily describe the specific fragmentation of USNM 459580, unless noted).
TOP: Shape: Test thick, turban-shaped; more or less depressed at the oral and anal apertures (Wright, 1864-1882)
AMB: Amb shape: Extremely narrow (Wright, 1864-1882)
Amb primary tubercles: Only minute tubercles or rows of small granules; never supporting tubercles with primary spines (Wright, 1864-1882)
Amb primary zones: Poriferous zones narrow, extending without interruption from buccal margin to apical disc (Wright, 1864-1882)
INTERAMB: Interamb width: Very wide (Wright, 1864-1882)
Interamb plating: Composed of large plates, rarely more than six to eight in a column (Wright, 1864-1882)
PORE PAIRS: Arrangement: In general unigeminal; in one genus bigeminal (Wright, 1864-1882) Pores contiguous or separated by septa more or less thick (Wright, 1864-1882)
TUBERCLES: Primary tubercles: Large, perforated tubercle on the external surface of each plate (Wright, 1864-1882)
Primary Areola shape: Round or oval; having an elevated margin (Wright, 1864-1882)
Primary Boss: Prominent (Wright, 1864-1882)
Secondary tubercles: Circle of granules on the areola margin, usually larger than those filling the miliary zone (Wright, 1864-1882)
APICAL SYSTEM: Size / Location: Opening very large; disc composed of five large, equal-sized angular genital plates and five ocular plates (Wright, 1864-1882)
PERIPROCT (ANUS): Location: Vent opening in the centre, directly opposite the mouth (Wright, 1864-1882)
Plating: Anal membrane clothed with small angular plates, unequal in size and variable in number (Wright, 1864-1882)
PERISTOME (MOUTH): Size: Wide, central (Wright, 1864-1882)
Shape: Circular or pentagonal; without notches (Wright, 1864-1882)
Plating: Aperture closed by buccal membrane covered with small spines metamorphosed into imbricated scales (Wright, 1864-1882)
Lantern: Jaws five in number, forming a very powerful lantern; teeth simple (Wright, 1864-1882)
SPINES: Shape: Large, strong; cylindrical, fusiform, prismatic, club-shaped, or flattened (Wright, 1864-1882)
Dimensions: Longest spine 23.3 mm; Width 3.3 mm (Specimen Data/Thompson, 2016)
Ornamentation: Surface covered with fine longitudinal lines, prickles, or granules (Wright, 1864-1882)
SPECIMENS STUDIED & CONDITION: Disarticulated plates and spines. Plate dimensions: 18.2 x 14.1 x 2.0 mm. Spine dimensions: 23.3 x 3.3 mm .
REMARKS & COMPARISONS
Remarks: The Cidaridae are the most ancient type of Echinoidea, found from the Paleozoic through the Tertiary (Wright, 1864-1882). The specimens from the Escondido Formation represent disarticulated remains assigned to the genus Cidaris (sensu lato).
Comparisons: Wright (1864-1882) listed historical genera such as Rabdocidaris (modern Rhabdocidaris), Diplocidaris, and Porocidaris within the family.
Plate: CiSp-10
Series: Upper Cretaceous Group: Navarro Formation: Escondido
Locale: Sabinal County: Uvalde Stage: Maastrichtian
Length: 18.2 mm Width: 14.1 mm Height: 2.0 mm
Specimen in photo: U.S.N.M. 459580
Paleobiology Depart. NMNH, Smithsonian Institution Plates.
Plate: CiSp-20
Series: Upper Cretaceous Group: Navarro Formation: Escondido
Locale: Sabinal County: Uvalde
Length: 23.3 mm (longest) Width: 3.3 mm
Specimen in photo: U.S.N.M. 459580
Paleobiology Depart. NMNH, Smithsonian Institution Spines.
Systematic Paleontology
CLASS: ECHINOIDEA Leske, 1778
SUBCLASS: CIDAROIDEA Smith, 1984
ORDER: CIDAROIDA Claus, 1880
FAMILY: CIDARIDAE Gray, 1825
GENUS: CIDARIS Leske, 1778
SPECIES: Cidaris sp.
TYPE SPECIES: Echinus cidaris Linnaeus, 1758
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Navarro
Formations: Escondido Formation
Stratigraphic Units: Upper Cretaceous, Maastrichtian
Counties: Uvalde County
DESCRIPTION
(Note: The following morphological descriptions are based on the Family/Generic definition provided by Wright (1864-1882) and do not necessarily describe the specific fragmentation of USNM 459580, unless noted).
TOP: Shape: Test thick, turban-shaped; more or less depressed at the oral and anal apertures (Wright, 1864-1882)
AMB: Amb shape: Extremely narrow (Wright, 1864-1882)
Amb primary tubercles: Only minute tubercles or rows of small granules; never supporting tubercles with primary spines (Wright, 1864-1882)
Amb primary zones: Poriferous zones narrow, extending without interruption from buccal margin to apical disc (Wright, 1864-1882)
INTERAMB: Interamb width: Very wide (Wright, 1864-1882)
Interamb plating: Composed of large plates, rarely more than six to eight in a column (Wright, 1864-1882)
PORE PAIRS: Arrangement: In general unigeminal; in one genus bigeminal (Wright, 1864-1882) Pores contiguous or separated by septa more or less thick (Wright, 1864-1882)
TUBERCLES: Primary tubercles: Large, perforated tubercle on the external surface of each plate (Wright, 1864-1882)
Primary Areola shape: Round or oval; having an elevated margin (Wright, 1864-1882)
Primary Boss: Prominent (Wright, 1864-1882)
Secondary tubercles: Circle of granules on the areola margin, usually larger than those filling the miliary zone (Wright, 1864-1882)
APICAL SYSTEM: Size / Location: Opening very large; disc composed of five large, equal-sized angular genital plates and five ocular plates (Wright, 1864-1882)
PERIPROCT (ANUS): Location: Vent opening in the centre, directly opposite the mouth (Wright, 1864-1882)
Plating: Anal membrane clothed with small angular plates, unequal in size and variable in number (Wright, 1864-1882)
PERISTOME (MOUTH): Size: Wide, central (Wright, 1864-1882)
Shape: Circular or pentagonal; without notches (Wright, 1864-1882)
Plating: Aperture closed by buccal membrane covered with small spines metamorphosed into imbricated scales (Wright, 1864-1882)
Lantern: Jaws five in number, forming a very powerful lantern; teeth simple (Wright, 1864-1882)
SPINES: Shape: Large, strong; cylindrical, fusiform, prismatic, club-shaped, or flattened (Wright, 1864-1882)
Dimensions: Longest spine 23.3 mm; Width 3.3 mm (Specimen Data/Thompson, 2016)
Ornamentation: Surface covered with fine longitudinal lines, prickles, or granules (Wright, 1864-1882)
SPECIMENS STUDIED & CONDITION: Disarticulated plates and spines. Plate dimensions: 18.2 x 14.1 x 2.0 mm. Spine dimensions: 23.3 x 3.3 mm .
REMARKS & COMPARISONS
Remarks: The Cidaridae are the most ancient type of Echinoidea, found from the Paleozoic through the Tertiary (Wright, 1864-1882). The specimens from the Escondido Formation represent disarticulated remains assigned to the genus Cidaris (sensu lato).
Comparisons: Wright (1864-1882) listed historical genera such as Rabdocidaris (modern Rhabdocidaris), Diplocidaris, and Porocidaris within the family.
