The fossil record of Eucommia (Eucommiaceae) in North America

Abstract

Reproductive and vegetative remains of Eucommia from 25 localities in the United States, Canada, and Mexico document the wide distribution of this genus in North America during the Cenozoic. Autofluorescent elastic latex filaments bearing capitate termini are preserved in nearly all of the remains and provide conclusive evidence of their affinity to Eucommia. Four species of Eucommia are recognized on the basis of the characteristic samaras: E. eocenica from middle Eocene strata of the Mississippi Embayment in Missouri, Tennessee and Mississippi; E. montana from early Eocene to early Oligocene localities in British Columbia, Washington, Oregon, Utah, Colorado, and Montana; E. constans from Neogene rocks in central Mexico; and E. jeffersonensis n. sp. from the latest Eocene or earliest Oligocene John Day Formation of Oregon. Atypical specimens of E. montana and E. eocenica are the first records of two-seeded fruits for the genus. Eucommia leaves from Eocene localities in British Columbia and Mississippi are the first records of Eucommia foliage in North America whose identifications are confirmed by the presence of capitate latex strands. These leaves and a specimen from Oregon are referred to E. rolandii n. sp. Fruit evolution in Eucommia may have involved increases in samara size and symmetry, and reduction in seed number from two to one, perhaps as adaptations for wind dispersal. All fossil Eucommia samaras from North America are smaller and less symmetrical than those of the living species, E. ulmoides. Preliminary flight tests of E. ulmoides samaras and of models of the fossils suggest that E. ulmoides fruits are aerodynamically better suited for wind dispersal than the fossils.

Paleocene wind-dispersed fruits and seeds from Colombia and their implications for early Neotropical rainforests

“…The comparative data for ulmaceous fruits were assembled from herbarium specimens (Tab. 3) as well as preexisting descriptions (Minaki et al 1988, Todzia 1989, Manchester 1989a, Wiegrefe et al 1994, Zavada & Kim 1996, Call & Dilcher 1997, Manchester & Tiffney 2001, Denk & Dillhoff 2005, Pell et al 2011. We reviewed 19 of 36 extant species of Ulmus, 9 of 12 species of Ampelocera, 4 of 6 species of Zelkova, 2 of 2 species of Phyllostylon and Holoptelea, and the monotypic genera Hemipte lea and Planera.…”

“…3, fig. 12) are considerably larger and thicker than those of Ulmaceae and Ulmoidicarpum, lack hairs along the margin, and possess abundant latex strands that are commonly preserved in fossils (Call & Dilcher 1997). Lastly, affinity with Euptelea (Eupteleaceae) can be ruled out because its samara has a very long stipe and two stigmatic crests that strongly protrude from the cleft (Pl.…”

The evolution and loss of oil-offering flowers: new insights from dated phylogenies for angiosperms and bees

“…The ages of the following most recent common ancestors were constrained based on fossils or in agreement with Wikström et al (2001), all with normal prior distributions: The Ericales stem to 110+4 Myr, the Zygophyllales stem to 98+3 Myr, the Fagales stem to 84 Myr, the Eucommia stem to 59-55 Myr, the Icacinaceae crown to 70+5 Myr, the Stilbaceae stem to 49+3 Myr and the Plantago-Antirrhinum split to 48+3 Myr. Eucommiaceae fossils are first known in the Late Cretaceous of Europe, but are most common in Eocene to Oligocene sediments (Call & Dilcher 1997); the oldest fruits of Icacinaceae (tribe Iodeae) come from the Late Paleocene of western North America (Pigg et al 2008). The earliest Fagales fossils may be ca 84 Myr old (Herendeen et al 1995), although the Normapolles genus Caryanthus, which belongs to crown group Fagales, is known from the Cenomanian and onwards (Friis et al 2006).…”

A review of paleobotanical studies of the Early Eocene Okanagan (Okanogan) Highlands floras of British Columbia, Canada, and Washington, USA

“…Additional significant plant remains found at Republic include Florissantia (Manchester 1992(Manchester , 1999, Eucommia (Call and Dilcher 1997), two forms of Ribes, Rhus and other Anacardiaceae foliage types, Cornus, Comptonia, Tilia johnsoni (Wolfe and Wehr 1987), Itea (Hermsen 2013), representatives of Bignoniaceae, Magnoliaceae, Melastomataceae (Renner et al 2001), Myrtaceae, and Lauraceae including Sassafras and other forms. Nuphar carlquistii (DeVore et al 2015) was recently published on the basis of fossil fruit and seed remains.…”