The Echinoid Directory

Thomasaster Lambert, 1920, p. 138

[=Tomasia Lambert 1918, p. 32 (non Poche, 1900)]

Diagnostic Features	Test of medium size, typically inflated, greatest width posterior to centre, greatest height anterior of centre; with rounded prominence over anterior margin; steep sides, rounded adoral surface, slightly depressed towards peristome Apical system anterior, tetrabasal with four gonopores Paired petals well developed, tapering distally, unequal. petal III absent. Interporiferous zones broad, poriferous zones narrow; pores conjugate. From the above figure, it would appear that ambulacrum III has a single series of double pores, but needs confirming Peristome longitudinal, slightly depressed Periproct inframarginal, longitudinally ovate Bourrelets weak or absent from figure Phyllode structure unknown Buccal pores unknown
Distribution	Cretaceous (Cenomanian) of Egypt
Name gender	masculine
Type	Archiacia araidahensis Gauthier, 1901, p. 46; by subsequent designation of Lambert 1920, p. 154.
Species Included	T. araidahensis (Gauthier, 1901); Cenomanian, Egypt
Classification and/or Status	Irregularia; stem group Neognathostomata; Archiaciidae ?Subjective junior synonym of Claviaster d'Orbigny, 1856.
Remarks	From Gauthier's figures (shown above) Thomasaster would appear to be similar to Claviaster, both genera having a single series of double pores in ambulacrum III. This character differentiates Thomasaster from Gentilia which has a double series of single pores in ambulacrum III. V. Gauthier 1901, in R. Fourtau. 1902. Notes sur le Echinides fossiles de l'Egypte. Bulletin de l'Institut Egyptien, 4 (2), 23-117 pp., 6 pls. Lambert, J. 1920. Revue critique Paleozoologie 24, p. 138. Lambert, J. 1920. Mem. Soc. Acad. Aube 84, p. 154-155.