The Star Formation Histories of Local Group Dwarf Galaxies II. Searching
  For Signatures of Reionization
  We search for signatures of reionization in the star formation histories
(SFHs) of 38 Local Group dwarf galaxies (10$^4$ $<$ M$_{\star}$ $<$ 10$^9$
M$_{\odot}$). The SFHs are derived from color-magnitude diagrams using archival
Hubble Space Telescope/Wide Field Planetary Camera 2 imaging. Only five
quenched galaxies (And V, And VI, And XIII, Leo IV, Hercules) are consistent
with forming the bulk of their stars before reionization, when full
uncertainties are considered. Observations of 13 of the predicted `true
fossils' identified by Bovill & Ricotti show that only two (Hercules and Leo
IV) indicate star formation quenched by reionization. However, both are within
the virial radius of the Milky Way and evidence of tidal disturbance
complicates this interpretation. We argue that the late-time gas capture
scenario posited by Ricotti for the low mass, gas-rich, and star-forming fossil
candidate Leo T is observationally indistinguishable from simple gas retention.
Given the ambiguity between environmental effects and reionization, the best
reionization fossil candidates are quenched low mass field galaxies (e.g., KKR
25).
