Data from: Palynology of a short sequence of the Lower Devonian Beartooth Butte Formation at Cottonwood Canyon (Wyoming): Age, depositional environments and plant diversity

The Beartooth Butte Formation hosts the most extensive Early Devonian macroflora of western North America. The age of the flora at Cottonwood Canyon (Wyoming) has been constrained to the Lochkovian-Pragian interval, based on fish biostratigraphy and unpublished palynological data. We present a detailed palynological analysis of the plant-bearing layers at Cottonwood Canyon. The palynomorphs comprise 32 spore, five cryptospore, two prasinophycean algae and an acritarch species. The stratigraphic ranges of these palynomorphs indicate a late Lochkovian - Pragian age, confirming previous age assignments. Analyses on samples from three different depositional environments of the plant-bearing sequence – layers with in situ lycophyte populations, flood layers that buried those populations and an organic matter accumulation zone within a flood layer – demonstrate distinct palynofacies. Comparisons between palynomorph and plant macrofossil diversity reveal some discrepancies. Whereas zosterophylls and lycophytes, most diverse and abundant among the macrofossils, have only one known corresponding spore type (assignable to zosterophylls) in the palynomorph assemblage, the trimerophytes, rare in the macrofossil assemblage, are represented by three spore types. Some of these discrepancies reflect taphonomic differences between macrofossils and palynomorphs, others could be due to the fact that the parent plants of most palynomorph types in the Cottonwood Canyon assemblage are unknown. These observations emphasize the need for concerted efforts to bring together the knowledge of macro- and microfloras within Early Devonian localities. Nevertheless, given the palaeophytogeographic significance of the Beartooth Butte Formation flora, its palyno- and macrofossil assemblages, taken together, provide new data relevant to future discussions of Early Devonian biogeography.比尔托特山组（Beartooth Butte Formation）产出了北美西部分布最广泛的早泥盆世大植物群。基于鱼类生物地层学与未发表的孢粉学数据，怀俄明州棉木峡谷（Cottonwood Canyon）该植物群的时代被限定为洛赫考夫期-布拉格期时限。本研究对棉木峡谷含植物地层开展了细致的孢粉学分析，所获孢粉型（palynomorphs）共计包含32种孢子、5种隐孢子（cryptospore）、2种扁藻藻类（prasinophycean algae）以及1种疑源类（acritarch）。这些孢粉型的地层延限指示其时代为晚洛赫考夫期-布拉格期，验证了此前的时代归属结论。对含植物地层序列中三种不同沉积环境的样品——原位石松类（lycophyte）种群层、掩埋该种群的洪水沉积层以及洪水层内的有机质富集带——开展的分析显示出显著差异的孢粉相（palynofacies）。对比孢粉型与植物大化石的多样性数据，可发现二者存在若干差异：尽管大化石组合中多样性与丰度最高的工蕨类（zosterophylls）和石松类，在孢粉型组合中仅有一种对应孢子类型（可归属于工蕨类），但大化石组合中较为稀有的三枝蕨类（trimerophytes）却对应三种孢子类型。上述部分差异源于大化石与孢粉型之间的埋藏学差异，其余差异则可能源于棉木峡谷孢粉型组合中多数类型的母体植物尚未被认知这一事实。上述研究结果凸显出，需协同整合早泥盆世各产地的大植物群与微植物群研究资料。尽管如此，鉴于比尔托特山组植物群的古植物地理学研究价值，其孢粉与大化石组合的整合数据可为未来早泥盆世生物地理学相关讨论提供新的依据。