Abstract

A fossil woodland/forest in Upper Cretaceous strata of the Aguja Formation in Big Bend National Park, Texas, preserves two species of dicotyledonous trees with trunks up to 1.3 m in diameter. The straight buttressed trunks, absence of low branching, and lack of distinct growth rings suggest that these trees represent a tropical evergreen community having a canopy height of 40 to 50 m. Well before the end of Cretaceous time, dicotyledonous angiosperms were the dominant canopy forming trees in at least some ecosystems in North America. These trees may have been among the woody plants that produced the Normapolles palynoflora.

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