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Bioerosion of Inorganic Hard Substrates in the Ordovician of Estonia (Baltica).

Vinn O, Wilson MA, Toom U - PLoS ONE (2015)

Bottom Line: Bioerosion is mostly associated with carbonate hardgrounds, but cobbles and pebbles broken from the hardgrounds are also often penetrated by Trypanites borings.The general diversity of boring ichnotaxa in Baltica increased from one ichnospecies in the Cambrian to seven by the end of Ordovician, showing the effect of the GOBE on bioeroding ichnotaxa.This difference can be explained by the wider environmental distribution of organic as compared to inorganic substrates in the Ordovician seas of Baltica, and their more continuous temporal availability, which may have caused increased specialization of several borers.

View Article: PubMed Central - PubMed

Affiliation: University of Tartu, Department of Geology, Tartu, Estonia.

ABSTRACT
The earliest bioeroded inorganic hard substrates in the Ordovician of Estonia appear in the Dapingian. Hardgrounds are also known from the Sandbian and Katian. Most of the bioerosion of inorganic hard substrates occurs as the boring Trypanites Mägdefrau, 1932 along with some possible Gastrochaenolites borings. North American hardground borings are more diverse than those in Baltica. In contrast to a worldwide trend of increasing boring intensity, the Estonian record seems to show no increase in boring intensities during the Middle and Late Ordovician. Hardgrounds seem to be more common during the temperate climate interval of the Ordovician calcite sea in Estonia (seven hardgrounds during 15 my) than in the part with a tropical climate (four hardgrounds during 12 my). Bioerosion is mostly associated with carbonate hardgrounds, but cobbles and pebbles broken from the hardgrounds are also often penetrated by Trypanites borings. The general diversity of boring ichnotaxa in Baltica increased from one ichnospecies in the Cambrian to seven by the end of Ordovician, showing the effect of the GOBE on bioeroding ichnotaxa. The diversity of inorganic hard substrate borers increased by only two times. This difference can be explained by the wider environmental distribution of organic as compared to inorganic substrates in the Ordovician seas of Baltica, and their more continuous temporal availability, which may have caused increased specialization of several borers. The inorganic substrates may have been bioreroded only by the generalists among boring organisms.

No MeSH data available.


Pebble with Trypanites.Toila Formation (Dapingian) from Suhkrumägi, dolomitized glauconitic limestone, northern Estonia. GIT 156–356.
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pone.0134279.g011: Pebble with Trypanites.Toila Formation (Dapingian) from Suhkrumägi, dolomitized glauconitic limestone, northern Estonia. GIT 156–356.

Mentions: The studied Dapingian limestone pebble has an irregular shape and slightly lens-shaped profile. Its surface is strongly mineralized (presumably with pyrite) and has a dark color. Trypanites borings are frequent (Fig 5). The surface of the pebble is slightly bumpy and bored by Trypanites from both sides. The distribution of Trypanites borings on the pebble is patchy. There are three possible small eroded bryozoans cemented to the pebble. The pebble contains 15 Trypanites borings per 4cm2. The maximum macroboring density index [25] ranges from 3 to 4. The Trypanites borings have diameters 0.7 to 2.9 mm (N = 19, mean 2.3 mm, sd = 0.62). The apertures of Trypanites are mostly circular, but some are slightly oval or subcircular, and some are merged (Fig 11). The Trypanites borings are filled with argillaceous limestone.


Bioerosion of Inorganic Hard Substrates in the Ordovician of Estonia (Baltica).

Vinn O, Wilson MA, Toom U - PLoS ONE (2015)

Pebble with Trypanites.Toila Formation (Dapingian) from Suhkrumägi, dolomitized glauconitic limestone, northern Estonia. GIT 156–356.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4517899&req=5

pone.0134279.g011: Pebble with Trypanites.Toila Formation (Dapingian) from Suhkrumägi, dolomitized glauconitic limestone, northern Estonia. GIT 156–356.
Mentions: The studied Dapingian limestone pebble has an irregular shape and slightly lens-shaped profile. Its surface is strongly mineralized (presumably with pyrite) and has a dark color. Trypanites borings are frequent (Fig 5). The surface of the pebble is slightly bumpy and bored by Trypanites from both sides. The distribution of Trypanites borings on the pebble is patchy. There are three possible small eroded bryozoans cemented to the pebble. The pebble contains 15 Trypanites borings per 4cm2. The maximum macroboring density index [25] ranges from 3 to 4. The Trypanites borings have diameters 0.7 to 2.9 mm (N = 19, mean 2.3 mm, sd = 0.62). The apertures of Trypanites are mostly circular, but some are slightly oval or subcircular, and some are merged (Fig 11). The Trypanites borings are filled with argillaceous limestone.

Bottom Line: Bioerosion is mostly associated with carbonate hardgrounds, but cobbles and pebbles broken from the hardgrounds are also often penetrated by Trypanites borings.The general diversity of boring ichnotaxa in Baltica increased from one ichnospecies in the Cambrian to seven by the end of Ordovician, showing the effect of the GOBE on bioeroding ichnotaxa.This difference can be explained by the wider environmental distribution of organic as compared to inorganic substrates in the Ordovician seas of Baltica, and their more continuous temporal availability, which may have caused increased specialization of several borers.

View Article: PubMed Central - PubMed

Affiliation: University of Tartu, Department of Geology, Tartu, Estonia.

ABSTRACT
The earliest bioeroded inorganic hard substrates in the Ordovician of Estonia appear in the Dapingian. Hardgrounds are also known from the Sandbian and Katian. Most of the bioerosion of inorganic hard substrates occurs as the boring Trypanites Mägdefrau, 1932 along with some possible Gastrochaenolites borings. North American hardground borings are more diverse than those in Baltica. In contrast to a worldwide trend of increasing boring intensity, the Estonian record seems to show no increase in boring intensities during the Middle and Late Ordovician. Hardgrounds seem to be more common during the temperate climate interval of the Ordovician calcite sea in Estonia (seven hardgrounds during 15 my) than in the part with a tropical climate (four hardgrounds during 12 my). Bioerosion is mostly associated with carbonate hardgrounds, but cobbles and pebbles broken from the hardgrounds are also often penetrated by Trypanites borings. The general diversity of boring ichnotaxa in Baltica increased from one ichnospecies in the Cambrian to seven by the end of Ordovician, showing the effect of the GOBE on bioeroding ichnotaxa. The diversity of inorganic hard substrate borers increased by only two times. This difference can be explained by the wider environmental distribution of organic as compared to inorganic substrates in the Ordovician seas of Baltica, and their more continuous temporal availability, which may have caused increased specialization of several borers. The inorganic substrates may have been bioreroded only by the generalists among boring organisms.

No MeSH data available.