Wyniki wyszukiwania - BazTech

1

Sclerobionts on organic substrates from the Late Paleocene Chehel-Kaman Formation, Kopet-Dagh Basin, NE Iran

Salahi A., El Hedeny M., Vinn O., Rashwan M.

Annales Societatis Geologorum Poloniae

|

2018

|

Vol. 88, No. 3

291--301

EN

Molluscs (oysters and gastropods) of the Late Paleocene Chehel-Kaman Formation, Kopet-Dagh Basin NE Iran were significantly colonized by sclerobionts. The largest area of the shells studied is covered by various borings. The diversity of macro-bioeroding ichnotaxa is rather high, including Gastrochaenolites Leymerie 1842; Maeandropolydora Voigt, 1965; Trypanites Mägdefrau, 1932; Talpina von Hagenow, 1840, and possibly Entobia Bronn, 1837. Some slightly conical borings penetrating the shells could belong to predatory tracemakers of Oichnus Bromley, 1981. Encrusters include calcareous polychaetes, cyclostome and cheilostome bryozoans, foraminifera and oysters. Calcareous sabellids [i.e. Glomerula serpentina (Goldfuss, 1831)] and serpulids are equally common sclerobionts in the association. Bryozoans cover a slightly larger area of the substrate than the calcareous polychaetes, while encrusting oysters are subordinate. The majority of fossils in the hard-substrate community studied belong to suspension feeders. Sclerobionts are typical of the shallow-marine environment, commonly in warm water. The present study is the first attempt to record the occurrence and diversity of epi- and endobionts in the organic substrates, present in the topmost part of the Late Paleocene Chehel-Kaman Formation, Kopet-Dagh Basin, NE Iran.

2

Cryptic encrusting fauna inside invertebrate fossils from the Ordovician of Estonia

Vinn O., Ernst A., Toom U., Isakar M.

Annales Societatis Geologorum Poloniae

|

2018

|

Vol. 88, No. 3

285--290

EN

This is the first report of encrusted cryptic surfaces in the Ordovician of Estonia. Only bryozoans and cornulitids occurred in nautiloids and trilobites. Bryozoans were the dominant encrusters, in terms of both the number of specimens and the encrustation area. Stalked echinoderms are common on the hardgrounds in the Middle and Upper Ordovician of Baltica, but the restricted space in nautiloid living chambers and trilobites probably prevented colonization by stalked echinoderms. Cryptic surfaces in nautiloids and trilobites usually are somewhat more encrusted than the open surfaces of hardgrounds in the Ordovician of Estonia. Encrusters presumably favoured cryptic surfaces, as these were less accessible for predators and grazers. Low encrustation densities, compared to North American hard substrates, seem to be characteristic for the Ordovician Baltic Basin.

3

Epi- and endobionts on the late Silurian (early Pridoli) stromatoporoids from Saaremaa Island, Estonia

Vinn O., Wilson M. A.

Annales Societatis Geologorum Poloniae

|

2012

|

Vol. 82, No. 3

195--200

EN

A diverse sclerobiont community is described from the Kaugatuma Formation (lower Pridoli) of Saare- maa, Estonia. The stromatoporoid substrates studied here vary from low-domical to high-domical shapes. The community is numerically dominated by microconchids, which may have been characteristic of the sclerobiont fauna in the Pridoli of Baltica. Palaeoconchus aff. tenuis, Anticalyptraea calyptrata, Aulopora sp., sheet-like bryozoans, branching bryozoans, erect bryozoan holdfasts, rugosans, favositids, discoidal crinoid holdfasts, star- like crinoid holdfasts and sheet-like stromatoporoids encrust the domical stromatoporoids. Endobionts are repre- sented by embedded, symbiotic rugosans, Aulopora sp., and two rare borings Trypanites.