The authors have declared that no competing interests exist.
Conceived and designed the experiments: OV MAW MAM. Performed the experiments: OV MAW MAM. Analyzed the data: OV MAW MAM. Contributed reagents/materials/analysis tools: OV MAW MAM. Contributed to the writing of the manuscript: OV MAW MAM.
The earliest
The oldest macroborings in the world are the small simple holes of
The bioerosion trace fossils of Ordovician of North America are relatively well studied
The aims of this paper are to: 1) determine whether the shafts in large Sandbian bryozoans belong to previously known or a new bioerosional ichnotaxon for the Ordovician; 2) determine the systematic affinity of the trace fossil; 3) discuss the ecology of the trace makers; 4) discuss the paleobiogeographic distribution of the trace fossil; and 4) discuss the occurrence of large borings during the Ordovician Bioerosion Revolution.
During the Ordovician, the Baltica paleocontinent migrated from the temperate to the subtropical realm
The total thickness of the Ordovician in Estonia varies from 70 to 180 m
The material studied here was collected from the Hirmuse Creek (
Location of Hirmuse Creek and Alliku Ditches in North Estonia.
The Middle and Upper Ordovician in Estonia. Location of
No permits were required for the described study, which complied with all relevant Estonian regulations, as our study did not involve collecting protected fossil species. Three described bryozoan specimens with the
Numerous unbranched, single-entrance, large deep borings with oval cross sections were found in three large trepostome bryozoan colonies (
Schematic line drawing showing a straight boring.
A bryozoan from Hirmuse Creek, Sandbian, Upper Ordovician, Estonia. Tr –
A bryozoan from Hirmuse Creek, Sandbian, Upper Ordovician, Estonia. Tr –
A bryozoan from Hirmuse Creek, Sandbian, Upper Ordovician, Estonia. Tr –
The borings in these bryozoans resemble somewhat
The other similar large Palaeozoic boring is
Most likely the
It is likely that
Morphological diversification was not the only result of the Ordovician Bioerosion Revolution. Most of the large bioerosional traces of the Paleozoic had their earliest appearances in the Ordovician
We are grateful to Ursula Toom for finding the specimens among the old collections of the Institute of Geology, Tallinn University of Technology. Ursula Toom, Prof. Dimitri Kaljo, Dr. Linda Hints, Dr. Helje Pärnaste from the Institute of Geology, Tallinn University of Technology and Dr. Mare Isakar from the Geological Museum of the University of Tartu Natural History Museum are thanked for identifications of the associated fossils. We are grateful to G. Baranov from Institute of Geology at TUT for technical help with images. We are grateful to Dr. Harry Mutvei and an anonymous reviewer for the constructive reviews.