Data presented here contribute to the results documented in the paper: Liang, Y., Nõlvak, J., Xu, H., Chen, Y. and Hints, O. (2021) Revision of Ordovician chitinozoan Lagenochitina esthonica sensu lato: morphometrics, biostratigraphy and paleobiogeography. Journal of Paleontology, in press.

Two datasets are included, one is Supplemental Data 1 cited in Liang et al. (2021) which contains detailed information of the occurrence data of previously published Lagenochitina esthonica. The other is Supplemental Data 2 cited in the paper which contains two sheets. One sheet named as "Original data"and it presents the original raw data of the measurements of Lagenochitina esthonica specimens obtained at the Jägala, Kaldase, Kaugatuma and Baldone sections, eastern Baltica. The other named as "Two forms", which divided the raw data into two groups for further statistical study.

Statistical morphometric study based on the measurements of L. esthonica indicates that two varieties could be recognized: a relatively short form with a test length around 400 μm and a L/Dp* ratio around 1.4–3.0, and a slender form usually longer than 600 μm in length with a L/Dp* ratio around 2.0–7.0.

Stratigraphic and geographic distributions based on available occurrence data suggest that the short form occurs in the upper Tremadocian to lower Dapingian, whereas the slender form is mostly reported from the lower and middle Darriwilian. Both forms are identified on Baltica; the short form has also been reported from Laurentia and South China, whereas the other is known also from Avalonia and Gondwana.

The morphological distinction, together with differences in stratigraphic and spatial ranges, suggest that the two forms represent separate species: the original stout L. esthonica, based on the morphology of the holotype, and the slender L. megaesthonica n. sp. described herein. The updated taxonomy enhances the stratigraphic and biogeographic usefulness of lagenochitinids globally.

The occurrence data are collected based on previously published literature.

The measurement data are measured based on optical images.

Measured specimens are obtained from the Ordovician outcrops and drill cores of the East Baltica. 

The README file contains an explanation of each of the variables in the dataset, its measurement units, and data collection information.