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)

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 0.2 mm (after Boczarowski 1997)

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

Archistrum gamma Hodson, Harris and Lawson, 1956 differs in presence of three holes in eye from Archistrun antiquum Boczarowski, 1997. Achistrum monochordata  Hodson, Harris and Lawson, 1956 presented on paper Gutschick, Canis and Brill (1967) differs in formation of eye, width of blade and thickness of eye trabecula from original described specimens from the Oxfordian of the United Kingdom by Hodson, Harris and Lawson (1956). Kinderhook specimen (Missisippian) is certainly some another species, very similar to descripted here but twice greater. Archistrum trassicum  Frizell and Exline, 1955 described by Kozur and Mock (1974) from Triassic of Slovak Republic, differs from Archistrun antiquum Boczarowski, 1997 (comp. Kozur, Mock, 1974) in having two eye pores with the same dimension. Calcligula triassica Kristan-Tollmann, 1964 from Triassic of Alps is bigger than Archistrun antiquum Boczarowski, 1997 and has a flat blade and thtee pores in eye (comp. Kristian-Tollmann, 1964). Other similar species were described by Fletcher (1962) from the Ampthiil Clay of Melton (Oxfordian of Yorkshire), Archistrum bichordatum Fletcher, 1962 which differs in having three eye pores from Archistrun antiquum Boczarowski, 1997 and Archistrum pilgrimi Fletcher, 1962 which is modifieed morphotype of Archistrum monochordata  Hodson, Harris and Lawson, 1956. All of them have similary formed abradial smaller pores.

Autekologia

Występowanie geograficzne

Zasięg czasowy

Type occurence only

Materiały muzealne

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.