Achistrum antiquum Boczarowski, 1997, dermal sclerite, radial and interradial oral plates in external and internal views; Late Permian Zechstein limestone, Kajetanów, Holy Cross Mts. (Dzik 1992, fig. 8.19B-E)

Reconstruction of the body of Achistrum antiquum Boczarowski, 1997. Arrow points to the front.

Calcareous Ring: ap - anterior processes, cc - central crest, fex - frontal excavation, if - internal face of plate, ir - interradial plate with the one proces, mir - muscle insertion region, of - outer face of plate, r - radial plate with the two proceses, rc - aperture for radial canal, vr - ventral radial plate.

Skeletal elements of Archistrum antiquum Boczarowski, 1997 from the Holy Cross mountains, Late Permian (Zechstein Werra), old abandoned quarry in Kajetanów.

Aggregate of hooks, GIUS 6-828 Kaj./1180/31. Scale bar = 200 micro

Diagnoza

Radial plating display more or less rectangular depression on the outer face. The area for longitudinal and retractor muscle insertion is elliptical in shape. The radial canal completly penetrates the notch. Hooks have two eye holes divided by slender trabecula with smaller opening situated abaxially.

Porównanie

Achistrum gamma differs in presence of three holes in eye . Kinderhookian specimen of A. monochordata  significantly differs from the type specimens from the Oxfordian and being similar to A. antiquum but is twice larger. A. trassicum  differs in having two eye pores with the same dimension. Calcligula triassica is larger and has a flat blade and three pores in eye. Other similar species from the Oxfordian have similary formed abradial smaller pores but A. bichordatum differs in having three eye pores and A. pilgrimi is a morphotype of A. monochordata  .

Autekologia

Występowanie geograficzne

Zasięg czasowy

Type locality only

Materiały muzealne

GIUs an ZPAL

Literatura

Boczarowski, A. 1997. Achistrum antiquus, a new species of apodid holothurian from the late Permian of the Holy Cross Mountains. Prace Państwowego Instytutu Geologicznego 157, 93-96. 

Dzik, J. 1992. Dzieje życia na Ziemi. Wprowadzenie do paleobiologii. 447 pp. Państwowe Wydawnictwo Naukowe. Warszawa.