The Cycadales are an ancient and charismatic group of seed plants. However, their morphological evolution in deep time is poorly understood. While molecular divergence time analyses estimate a Cretaceous origin for most major living cycad clades, much of the extant diversity is inferred to be a result of Neogene diversifications. This leads to long branches throughout the cycadalean phylogeny that, with few exceptions, have yet to be rectified by unequivocal fossil cycads. We report a permineralized pollen cone from the Campanian Holz Shale located in Silverado Canyon, CA, USA ( Microsporophyll and pollen morphology indicate this cone is assignable to Our findings support a Cretaceous diversification for crown‐group Zamiaceae, which included the evolution of morphological divergent extinct taxa with unique traits that have yet to be widely identified in the fossil record.
Hagfish depart so much from other fishes anatomically that they were sometimes considered not fully vertebrate. They may represent: (
- NSF-PAR ID:
- 10083739
- Publisher / Repository:
- Proceedings of the National Academy of Sciences
- Date Published:
- Journal Name:
- Proceedings of the National Academy of Sciences
- Volume:
- 116
- Issue:
- 6
- ISSN:
- 0027-8424
- Page Range / eLocation ID:
- p. 2146-2151
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Summary c. 80 million yr ago). This fossil was studied via serial sectioning, SEM, 3D reconstruction and phylogenetic analyses.Skyttegaardia , a recently described genus based on disarticulated lignitized microsporophylls from the Early Cretaceous of Denmark. Data from this new species, including a simple cone architecture, anatomical details and vasculature organization, indicate cycadalean affinities forSkyttegaardia . Phylogenetic analyses support this assignment and recoverSkyttegaardia as crown‐group Cycadales, nested within Zamiaceae. -
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