Eucalyptocrinitidae Roemer, 1855

Ausich, William I., Wilson, Mark A. & Vinn, Olev, 2012, Crinoids from the Silurian of Western Estonia, Acta Palaeontologica Polonica 57 (3), pp. 613-631 : 618-620

Family Eucalyptocrinitidae Roemer, 1855 Genus Eucalyptocrinites Goldfuss, 1831

Type species: Eucalyptocrinites rosaceus Goldfuss, 1831 ; Eifel , Germany; Eifelian .

Discussion.— Eucalyptocrinites spp. are the most abundant crinoids from the Silurian of Estonia. On many beach sections, dozens of calyxes are preserved in limestone beds and are readily identifiable to genus, which, as mentioned above, makes it all the more surprising that this cosmopolitan crinoid was not reported from Estonian until Hints and Stukalina (1997). Eucalyptocrinites is known currently from the Wenlock and Pridoli of Estonia. Both the calyx and tegmen are very distinctive in this genus. Eucalyptocrinites is taphonomically robust whether the theca is preserved intact or separated into the calyx and tegmen. Many juveniles, as well as adults, are preserved. Unfortunately, most specimens are only preserved calyxes, a portion of the arms with partition plates, a broken crown, or some broken combination.

Species distinctions within Eucalyptocrinites include variability in calyx shape; relative height of the basal circlet; calyx, tegmen, and arm plate sculpturing (smooth, nodose, or other types of sculpturing); shape of partition plates; shape of the distal tegmen; spinosity of the partition plates; presence or absence of an anal tube; and spinosity or other sculpturing around the anal opening at the summit of the tegmen. The only other Silurian Eucalyptocrinites reported from Baltica are from the Wenlock through Ludlow of Gotland, Sweden. On Gotland, Franzén (1983) recognized ten species, whereas Webster (2003) listed only nine. Based on the illustrations of Gotland specimens in Angelin (1878), Eucalyptocrinites can be divided into species with smooth or with variously sculptured calyx plates. Those with smooth calyx plates are of three types: (i) E. plebejus ( Angelin, 1878) , E. regularis (Hisinger, 1840) , and E. rigens ( Angelin, 1878) have smooth calyx plate sculpturing, low cone−shaped calyx, flat or convex base, basals not visible, and partition plates conspicuously widened; (ii) E. minor ( Angelin, 1878) has smooth calyx plate sculpturing, low bowl−shaped calyx, very low convex base, basals visible, and partition plates conspicuously widened; and (iii) E. ovatus ( Angelin, 1878) has smooth calyx plate sculpturing, low bowl−shaped calyx, very low convex base, basals not visible, and partition plates not conspicuously widened. In addition, some species from Gotland have distinctive calyx plate sculpturing, including E. decoratus ( Angelin, 1878) , E. elegantissimus ( Angelin, 1878) , E. excellentissimus ( Angelin, 1878) , and E. speciosus ( Angelin, 1878) .

http://dx.doi.org/10.4202/app.2010.0094

Three species−level taxa of Eucalyptocrinites are now recognized from Estonia. One has distinctive calyx plate sculpturing, Eucalyptocrinites tumidus sp. nov., which is described below. Those with smooth plate sculpturing are difficult to evaluate and are referred to here as Eucalyptocrinites sp. 1 and Eucalyptocrinites sp. 2 . Complete specimens are needed to evaluate all species−level characters; and, typically, only an isolated calyx or an isolated partition plate assembly is preserved. Furthermore, a wide size range exists among known specimens. Perhaps the most common preservational mode is for a calyx, all or partly visible, to be preserved upside−down on a bedding surface. If partially buried to preserve only the proximal−most calyx, it appears that the calyx shape has a lower height−to−width ratio than if the entire calyx was exposed.

The majority of known specimens have smooth calyx plates, and the majority of these are isolated calyxes or tegmen. Thus, the majority of Estonian Eucalyptocrinites specimens are not preserved sufficiently well enough to identify beyond Eucalyptocrinites spp.