Abstract Detail

Paleobotany

Pfeiler, Kelly C. [1], Ortiz, Ashley [2], Kammet, Ashley [1], Bippus, Alexander C. [1], Tomescu, Alexandru [3].

Exploring the relationships of an anatomically-preserved cupressaceous seed cone from the Lower Cretaceous of California.

The Cupressaceae have an extensive fossil record going back as far as the Jurassic, and possibly the Triassic, with some extant genera present as early as the Early Cretaceous. Fossil seed cones assigned to the Cupressaceae are diverse and have been included in phylogenetic analyses aimed at resolving relationships within the family. Of these fossils, anatomically-preserved seed cones provide the most valuable information for such studies. A seed cone discovered in the Lower Cretaceous Budden Canyon Formation (California), close to the Barremian-Aptian boundary (ca. 125 Ma), represents an early occurrence for the family, with potential implications for relationships among basal Cupressaceae. This is the second type of anatomically-preserved seed cone assigned to the Cupressaceae, discovered in this rock unit. The cone is 9 mm long, 6 mm in diameter, with an axis 1.2 mm in diameter bearing 22-28 helically arranged bract-scale complexes (ovuliferous scales). The bract-scale complexes are up to 1.9 mm long. They have a cuneate base and a polygonal peltate head up to 2.4 mm tall and up to 1.7 mm wide. One central resin canal runs the length of the bract-scale complex; in the wider portion of the latter, two shorter lateral canals run parallel and at the same level with the central canal. The vascular supply of bract-scale complexes consists of very thin adaxially positioned bundles; up to five such bundles diverge in a horizontal plane from the main bundle that supplies the base of the bract-scale complex. Morphologically, this cone shares some features with extant genera in early-divergent lineages of the Cupressaceae: Sequoia and Sequoiadendron (sequoioids), Cryptomeria and Taxodium (taxodioids), and Athrotaxis. The Budden Canyon cone is the oldest fossil that shares features of these lineages. Both its age and its morphology suggest that this cone represents an early-diverging taxon in the Cupressaceae. Among younger Cretaceous cupressaceous cones, the Budden Canyon cone shares features with Quasisequoia, Parataxodium, Athrotaxites, and Austrosequoia. Some of these are permineralized fossils that allow for direct comparisons of bract-scale complex anatomy with extant genera and the Budden Canyon cone. The comparisons will explore vascular architecture and resin canal geometry of bract-scale complexes and the resulting data will be incorporated into a morphological phylogenetic matrix to address the placement of the Budden Canyon cone, with the potential to inform understanding of relationships at the base of the Cupressaceae.

1 - Humboldt State University, Biological Sciences, 1 Harpst Street, Arcata, CA, 95521, USA
2 - 76 East Oxford Street, Chula Vista, CA, 91911, USA
3 - Humboldt State University, Department Of Biological Sciences, 1 Harpst Street, Arcata, CA, 95521, USA

Keywords:
Paleobotany
fossil
anatomy
conifers
seed cone
phylogeny
permineralization
evolution
Cupressaceae
Cretaceous
California
ovulate cone.

Presentation Type: Oral Paper
Session: 12, Cookson/Moseley award presentations
Location: Sundance 4/Omni Hotel
Date: Monday, June 26th, 2017
Time: 1:45 PM
Number: 12002
Abstract ID:177
Candidate for Awards:Isabel Cookson Award,Maynard F. Moseley Award