Faunal Turnover and Evolution in Response to Climate Change in Mollusks of the Eocene La Meseta Formation, Seymour Island, Antarctic Peninsula

This data set includes numerical collection abundance, morphometrics, and
observations of naticid shell-drilling predation in mollusks recovered from
the Eocene La Meseta Formation, Seymour Island, Antarctic Peninsula. Abundance
data for both 21 bivalve genera and 39 gastropod genera are tabulated for each
of three stratigraphic units (sequence 1, 2, and 3 corresponding to the lower,
middle, and upper portions of the La Meseta Formation). Total collections
consist of 5,707 bivalves and 6,824 gastropods.

Morphometric data consist of measurements of seven attributes of shell
morphology (shell width, shell height, thickness of outer lip, length of
spire, height of penultimate whorl, apertural length, and apertural width) for
two particularly abundant gastropod genera, Antarctodarwinella (represented by
171 measured specimens) and Polinices (represented by 268 measured specimens).
Measurements are reported in millimeters and were made with digital calipers
accurate to 0.02 millimeters. Locality and stratigraphic occurrence of each
individual are also reported.

Naticid shell-drilling data consist of outer borehole diameter, prey height,
and prey width measurements, as well as a determination of lethality or
sublethality for each predatory attack. Morphometric data are reported in
millimeters and were made with digital calipers accurate to 0.02 millimeters.
Locality and stratigraphic occurrence of each individual are also reported.
Data were collected from the bivalve Eurhomalea (197 drilled individuals) and
the gastropod Polinices (104 drilled individuals, representing cannibalistic
attacks). For Eurhomalea, the type of valve (left or right) bearing the
borehole is indicated, and borehole placement is binned into shell quadrants
(anteriodorsal, anterioventral, posteriodorsal, posterioventral). For
Polinices, borehole placement is binned into five shell sectors: 1 (= last 90
degrees of last whorl), 2 (= penultimate 90 degrees of last whorl), 3 (between
180 and 270 degrees from outer lip on last whorl), 4 (= first 90 degrees of
last whorl), and 5 (= spire).

Specimens were collected by field parties directed by R. B. Aronson and D. B.
Blake. This data set was made possible by National Science Foundation grants
OPP-9908828 (Aronson) and OPP-9908856 (Blake).