The Conifer Frenelopsis ramosissima (Cheirolepidiaceae) in the Lower Cretaceous of Texas: Systematic, Biogeographical, and Paleoecological Implications

• DOI: 10.1086/427202
• Publication Date: 2005-03-29T10:16:45Z
• Authors: Brian J. Axsmith; Bonnie Fine Jacobs
• Keywords: Tamarix; Paleoecology; Paleobotany; Taxodium

Until now, our knowledge of the Lower Cretaceous conifer Frenelopsis ramosissima was based exclusively on branches from a few sites in Potomac Group eastern Virginia and Maryland. Affinities with important Mesozoic family Cheirolepidiaceae have been assumed despite historical absence diagnostic attached or associated Classopollis‐producing pollen cones. This plant has reconstructed as small, stem‐succulent shrub that inhabited diverse, mesic communities. Here, we present reconsideration F. new fossils Jones Ranch sauropod dinosaur quarry site (Twin Mountains Formation) near Glen Rose, Texas, which represents ca. 2100‐km range extension for this conifer. Compelling support assignment to is provided by first account cones situ Classopollis‐type pollen. Features remains are consistent determination, including ovulate persistent bracts, cone scales probable epimatium, wood mixed pitting tracheid radial walls. Our analysis Texas refutes seriously challenges many widely accepted hypotheses regarding biogeography, structure, paleoecology ramosissima. For example, can no longer be considered Group–endemic taxon. Furthermore, taphonomy sedimentology locality indicate monospecific stand plants semiarid climate rather than diverse community, indicated occurrences. Finally, logs large tree (at least 22.4 m tall, extrapolated maximum trunk diameter) abundant lower branch orders.