Summary Pith in woody species fulfills essential roles, from functioning as the first vascular ti... more Summary Pith in woody species fulfills essential roles, from functioning as the first vascular tissue in shoots, to serving as starch storage and facilitating heartwood formation. While the spongy cells of pith may die and be reabsorbed at maturity by some species, the pith persists throughout the lifespan of conifer trees. Pith features and functions of extant conifers have been documented in contemporary studies, and pith anatomy has been described for extinct progymnosperms and coniferous ancestors through fossils. However, up to now, few studies have described the wood anatomy of pith in living conifers and covered only 24 species in four families. Here we describe the pith of 7 genera and 16 species from the previously unstudied conifer families of Araucariaceae and Podocarpaceae, based on stained and unstained cross-sections. Comparisons between pith sections of the same tree in successive years yielded insights into maturation of the conifer pith. Conservative pith characteristics were identified among genera and families. Araucariaceae pith is dissimilar on a familial level, but the genus Araucaria is unified by pith shape and heterocellularity. In contrast, all Podocarpaceae piths develop secondary cracks, and most species have irregularly shaped piths. Beyond our study of similarities and differences of pith in Araucariaceae and Podocarpaceae, a look at pith patterns in the paleobotanical record and further examples in living conifers could increase the understanding of conserved characteristics and pith evolution.
textThe Early Cretaceous (Berriasian) Hope Bay flora is one of the most diverse assemblages from ... more textThe Early Cretaceous (Berriasian) Hope Bay flora is one of the most diverse assemblages from the Mesozoic of Antarctica. Collected in 1902 by the Swedish Antarctic Expedition of 1901-1903 from Hope Bay at the northern tip of the Antarctic Peninsula, and described in 1913 by T. G. Halle, it has served as a classic reference collection for Jurassic and Cretaceous southern hemisphere paleobotanical studies. Because the systematics of the flora were outdated by the enormous advances in our understanding of fossil plants during the last 70 years, it was in serious need of revision. This revision has reduced the number of taxa from 61 to 42 species. Newly erected species are Otozamites rowleyi, Kachchhia schopfii, Ticoa jeffersonii, and Araucaria antarctica. New combinations are Todites grahamii and Thinnfeldia salicifolia. The genera Kachchhia, Ticoa, and Weltrichia are new occurrences at Hope Bay. Represented in the flora are members of the Hepatophyta, Arthrophyta, Pteridophyta, Pteridospermophyta, Cycadophyta, Cycadeoidophyta, and Coniferophyta. Not surprisingly, when compared with other Gondwana floras, the Hope Bay flora shows the greatest similarity with other Antarctic floras. There is also a close affinity with the floras of South America and New Zealand. Taxonomic similarity between these floras is best explained by paleogeographic proximity.Plant Biolog
... like gastric mill, arguing that pebble aggregations inter-preted as gastric mills are a sedim... more ... like gastric mill, arguing that pebble aggregations inter-preted as gastric mills are a sedimentological phenomenon (Calvo 1994a; Lucas 2000; Wings ... Extant large herbi-vores and particularly megaherbivores all have to focus their feeding on cell wall-rich vegetative plant parts ...
International Journal of Plant Sciences, Sep 1, 2019
Premise of research. Although the Nymphaeaceae are an ancient angiosperm family, fossil leaves wi... more Premise of research. Although the Nymphaeaceae are an ancient angiosperm family, fossil leaves with nymphaeacean affinities from the Paleogene have nearly always been assigned to modern genera. Yet during the diversification of this group, it is extremely likely that transitional forms in this family evolved since its origin over 100 million years ago and should show up in the fossil record. Here, we describe an extinct genus of nymphaeacean leaf with transitional characters from the Eocene Lake Messel locality, which is, according to phylogenetic analysis, a member of the main Nymphaeaceae clade excluding Nuphar. Methodology. Over 39 fossil leaves from the Messel Pit near Darmstadt, Germany, were studied, coded for 40 of 55 morphological and leaf architecture characters, and analyzed phylogenetically. Analyses were run with PAUP* of the Messel leaf morphotype combined with living taxa and then together with previously described fossil Nymphaeales. Pivotal results. Inclusion of the Messel leaf with living taxa results in three trees with similar topology except for the relationship within Nuphar. Bootstrap data strongly support inclusion of the Messel leaf in the order Nymphaeales and the family Nymphaeaceae. In analyses with only living taxa, the Messel leaf places beyond Nuphar within the remaining Nymphaeaceae. In analyses with living and other fossil taxa, it places at the base of the Nuphar clade. Based on its suite of characters, the Messel leaf is recognized here as an intermediate between existing genera and described as a new extinct genus and species. Conclusions. The Eocene water lily from Messel is described here as a new genus and species, Nuphaea engelhardtii Gee and David W. Taylor gen. et sp. nov., and is represented by leaves with characters that are transitional to those of modern Nuphar, Nymphaea, and other Nymphaeaceae. This study offers new evidence of greater biodiversity in Nymphaeaceae in the Cenozoic.
Summary Pith in woody species fulfills essential roles, from functioning as the first vascular ti... more Summary Pith in woody species fulfills essential roles, from functioning as the first vascular tissue in shoots, to serving as starch storage and facilitating heartwood formation. While the spongy cells of pith may die and be reabsorbed at maturity by some species, the pith persists throughout the lifespan of conifer trees. Pith features and functions of extant conifers have been documented in contemporary studies, and pith anatomy has been described for extinct progymnosperms and coniferous ancestors through fossils. However, up to now, few studies have described the wood anatomy of pith in living conifers and covered only 24 species in four families. Here we describe the pith of 7 genera and 16 species from the previously unstudied conifer families of Araucariaceae and Podocarpaceae, based on stained and unstained cross-sections. Comparisons between pith sections of the same tree in successive years yielded insights into maturation of the conifer pith. Conservative pith characteristics were identified among genera and families. Araucariaceae pith is dissimilar on a familial level, but the genus Araucaria is unified by pith shape and heterocellularity. In contrast, all Podocarpaceae piths develop secondary cracks, and most species have irregularly shaped piths. Beyond our study of similarities and differences of pith in Araucariaceae and Podocarpaceae, a look at pith patterns in the paleobotanical record and further examples in living conifers could increase the understanding of conserved characteristics and pith evolution.
textThe Early Cretaceous (Berriasian) Hope Bay flora is one of the most diverse assemblages from ... more textThe Early Cretaceous (Berriasian) Hope Bay flora is one of the most diverse assemblages from the Mesozoic of Antarctica. Collected in 1902 by the Swedish Antarctic Expedition of 1901-1903 from Hope Bay at the northern tip of the Antarctic Peninsula, and described in 1913 by T. G. Halle, it has served as a classic reference collection for Jurassic and Cretaceous southern hemisphere paleobotanical studies. Because the systematics of the flora were outdated by the enormous advances in our understanding of fossil plants during the last 70 years, it was in serious need of revision. This revision has reduced the number of taxa from 61 to 42 species. Newly erected species are Otozamites rowleyi, Kachchhia schopfii, Ticoa jeffersonii, and Araucaria antarctica. New combinations are Todites grahamii and Thinnfeldia salicifolia. The genera Kachchhia, Ticoa, and Weltrichia are new occurrences at Hope Bay. Represented in the flora are members of the Hepatophyta, Arthrophyta, Pteridophyta, Pteridospermophyta, Cycadophyta, Cycadeoidophyta, and Coniferophyta. Not surprisingly, when compared with other Gondwana floras, the Hope Bay flora shows the greatest similarity with other Antarctic floras. There is also a close affinity with the floras of South America and New Zealand. Taxonomic similarity between these floras is best explained by paleogeographic proximity.Plant Biolog
... like gastric mill, arguing that pebble aggregations inter-preted as gastric mills are a sedim... more ... like gastric mill, arguing that pebble aggregations inter-preted as gastric mills are a sedimentological phenomenon (Calvo 1994a; Lucas 2000; Wings ... Extant large herbi-vores and particularly megaherbivores all have to focus their feeding on cell wall-rich vegetative plant parts ...
International Journal of Plant Sciences, Sep 1, 2019
Premise of research. Although the Nymphaeaceae are an ancient angiosperm family, fossil leaves wi... more Premise of research. Although the Nymphaeaceae are an ancient angiosperm family, fossil leaves with nymphaeacean affinities from the Paleogene have nearly always been assigned to modern genera. Yet during the diversification of this group, it is extremely likely that transitional forms in this family evolved since its origin over 100 million years ago and should show up in the fossil record. Here, we describe an extinct genus of nymphaeacean leaf with transitional characters from the Eocene Lake Messel locality, which is, according to phylogenetic analysis, a member of the main Nymphaeaceae clade excluding Nuphar. Methodology. Over 39 fossil leaves from the Messel Pit near Darmstadt, Germany, were studied, coded for 40 of 55 morphological and leaf architecture characters, and analyzed phylogenetically. Analyses were run with PAUP* of the Messel leaf morphotype combined with living taxa and then together with previously described fossil Nymphaeales. Pivotal results. Inclusion of the Messel leaf with living taxa results in three trees with similar topology except for the relationship within Nuphar. Bootstrap data strongly support inclusion of the Messel leaf in the order Nymphaeales and the family Nymphaeaceae. In analyses with only living taxa, the Messel leaf places beyond Nuphar within the remaining Nymphaeaceae. In analyses with living and other fossil taxa, it places at the base of the Nuphar clade. Based on its suite of characters, the Messel leaf is recognized here as an intermediate between existing genera and described as a new extinct genus and species. Conclusions. The Eocene water lily from Messel is described here as a new genus and species, Nuphaea engelhardtii Gee and David W. Taylor gen. et sp. nov., and is represented by leaves with characters that are transitional to those of modern Nuphar, Nymphaea, and other Nymphaeaceae. This study offers new evidence of greater biodiversity in Nymphaeaceae in the Cenozoic.
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