Few species of Polemoniaceae inhabit environments where burial, sedimentation, and ultimately fossilization are likely to occur. Consequently, the fossil record of Polemoniaceae is poor. Lott et al. (1998) review the fossil history of this family, which consists primarily of pollen grains: from the middle Eocene in Spain, from the Pliocene in Europe (attributed to a fossil-genus, Polemoniopollis), and Gilia type 1-like pollen (Stuchlik, 1967) from Miocene deposits in Northern California. The only megafossil currently contributed to Polemoniaceae, Gilisenium hueberi, is a nicely preserved compression-impression fossil from mid-eocene shale deposits taken from the Green River Formation in Utah (USA; Lott et al., 1998). This fossil of a taprooted, herbaceous plant is very similar to extant Gilia species and provides an important calibration point for estimating the timing of the origin of the phlox family and various groups within this family.
Gilisenium hueberi, Type specimen. This is the sole macrofossil of Polemoniaceae. Image copyright © 2003, courtesy of the Department of Paleobiology, National Museum of Natural History, Smithsonian Institution.
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