Replicability is a key concept in science. The citation of extant material used for comparative purposes in palaeobotanical studies is the sine qua non of this replicability. However, there is no ...standard for citing herbarium sheets, personal collections, or field pictures of specimens. Here, I propose a simple citation guideline for all these cases, emphasizing the citation of the voucher specimens using the collector's name and collection number.
•Replicability is a key concept in science.•There is no standard for citing extant specimens in palaeobotany.•I propose a simple citation guideline for different cases of extant specimens.
Premise of research. The Anacardiaceae family is distributed throughout the vegetated continents. The fossil record indicates extensive diversification of the family during the Paleogene and, in ...particular, during the Eocene. Despite the abundant fossil record of this period, there are only a few reliable anacardiaceous fossils in the Paris Basin. Here, we aim to document newly recognized fossils of Anacardiaceae from the Paris Basin, understand their paleoecology, and discuss their biogeographic history.
Methodology. Thirty-three lignite fruits were examined from two sites, one before and one after the Paleocene-Eocene boundary (i.e., Petit Pâtis Rivecourt and Le Quesnoy Houdancourt). The specimens were photographed, and anatomy was studied using computed tomography and histological sections. Comparative analyses were undertaken using available descriptions of fossil and modern fruits of Anacardiaceae.
Pivotal results. A new species, Cyrtocarpa biapertura sp. nov., is described on the basis of a unilocular fruit with two prominent apertures present on the ventral side of the endocarp, protruding into two lacunae surrounding the locule. Taphonomic analysis indicates that this plant grew close to riverbanks. Furthermore, a new record of “Lannea” europaea (Reid and Chandler) Chandler is reported for the Eocene site.
Conclusions. The occurrence of Cyrtocarpa in both the Paleocene and the Eocene floras in the Paris Basin suggests similar vegetation during both time intervals. It is likely that both floras grew under similar subtropical climates. Moreover, it appears that the early Eocene shows an enrichment of the paleodiversity of Anacardiaceae and other plant families in the Paris Basin. The presence of Cyrtocarpa documents a rarely reported disjunction between the Paleogene of Europe and the recent tropical flora of South America.
Tibet’s ancient topography and its role in climatic and biotic evolution remain speculative due to a paucity of quantitative surface-height measurements through time and space, and sparse fossil ...records. However, newly discovered fossils from a present elevation of ∼4,850 m in central Tibet improve substantially our knowledge of the ancient Tibetan environment. The 70 plant fossil taxa so far recovered include the first occurrences of several modern Asian lineages and represent a Middle Eocene (∼47 Mya) humid subtropical ecosystem. The fossils not only record the diverse composition of the ancient Tibetan biota, but also allow us to constrain the Middle Eocene land surface height in central Tibet to ∼1,500 ± 900 m, and quantify the prevailing thermal and hydrological regime. This “Shangri-La”–like ecosystem experienced monsoon seasonality with a mean annual temperature of ∼19 °C, and frosts were rare. It contained few Gondwanan taxa, yet was compositionally similar to contemporaneous floras in both North America and Europe. Our discovery quantifies a key part of Tibetan Paleogene topography and climate, and highlights the importance of Tibet in regard to the origin of modern Asian plant species and the evolution of global biodiversity.
Flowers embedded in amber are rare. Only about 70 flowers or inflorescences have been described among which only one lamiid is known. Nevertheless, these fossils are important to our understanding of ...evolutionary process and past diversity due to the exceptional preservation of fragile structures not normally preserved. In this work, a new flower named Icacinanthium tainiaphorum sp. nov. from Le Quesnoy (Houdancourt, Oise, France) is described. Our phylogenetic analysis with extant species suggests that the affinity of this flower lies with the family Icacinaceae, close to Natsiatum or Hosiea. The fossil shows a combination of features unknown in extant Icacinaceae and we thus propose the description of a new fossil genus. It reveals a previously unknown diversity in the family and demonstrates the complementarity of different types of fossil preservation for a better understanding of past floral diversity.
The fossil record of the diverse subfamily Passifloroideae (>750 species and 17 genera) is relatively poor. Despite the distinctiveness of its leaves (glandular and often emarginate), most of the ...fossils from this group have been described from seeds. Fossil seeds have been recovered from Europe, and North and South America. A lack of information on seed morphology for all the genera and tribes of this subfamily has prevented a tribe-level identification of the fossils and a better understanding of their biogeographic patterns. The Passifloroideae is divided into three tribes: Passifloreae with 10 genera, Paropsieae with six genera and the monotypic Jongkindieae. This study provides new descriptions for 15 species from 5 genera from the mostly Afrotropical tribe Paropsieae based on herbarium material, and introduces an online seed database and a key for 100 species of Passifloroideae compiled from literature and direct observations. Our study shows a low morphological diversity among the seeds of Paropsieae in comparison to a much larger diversity within Passifloreae. Some rare morphologies are only present in Passifloreae and can be used to assign seeds to this tribe. Within the Paropsieae, Androsiphonia has seed that are very distinct from those in the other genera in the tribe and also from the rest of the subfamily. The genus Paropsia exhibits two main morphotypes, while the genera Barteria, Paropsiopsis and Smeathmannia have very similar seeds with a highly conserved morphology. These results suggest that living or fossil Paropsieae cannot be identified confidently based solely on seed characters.
Premise
Apocynaceae is common in the fossil record, especially as seed remains from the Neogene of Europe and North America, but rare in Asia. Intrafamilial assignment is difficult due to the lack of ...diagnostic characters, and new fossil and modern data are needed to understand the paleobiogeography of this group.
Methods
We studied three Apocynaceae seed impressions from the Lower Eocene Niubao Formation, Jianglang village, Bangor County, central Qinghai‐Tibetan Plateau. Morphological data from living and fossil species were phylogenetically mapped to enable systematic assignment.
Results
We describe a new genus, Asclepiadospermum gen. nov., and two new species, A. marginatum sp. nov. and A. ellipticum sp. nov. These species are characterized by an elliptical seed, a margin surrounding the central part of the seed, and polygonal, irregular, and small epidermal cells, and differ mainly in terms of the size of the margin and the shape of the apex. All these characters indicate that this new genus belongs to the subfamily Asclepiadoideae (Apocynaceae).
Conclusions
These fossils represent the earliest fossil seed records of Asclepiadoideae. Asclepiadospermum indicates a humid tropical to subtropical flora during the early Eocene in central Tibet. Moreover, our discoveries indicate a close floristic connection between Eurasia and Africa during the early Eocene, which expands our knowledge of the floristic linkage between Tibet and other regions at that time.
In the past decades, the concept of Icacinaceae has been refined greatly, as morphological and molecular data have led to a narrower circumscription of a monophyletic Icacinaceae family with only 23 ...genera (vs 58 sensu Sleumer, 1942). This family possesses an extensive fossil record, important to the biogeographic history of the Northern Hemisphere, but the reported fossils need to be carefully evaluated in the current phylogenetic framework. We evaluated 183 fossil reports of Icacinaceae from the literature but considered only 92 as reliably belonging to this family. Most of the accepted records are from endocarp remains. With this sampling, we show an increase of the species richness during the Paleocene. A great increase of diversity in terms of genera, species, and morphological range is shown through the Paleocene–Eocene interval and during the Early Eocene (Ypresian). Exchanges occurred between North America and Europe near the PETM in both directions. During the middle and late Eocene, several of the modern genera appear first in the fossil record such as Natsiatum, Phytocrene, and Pyrenacantha. Decreased diversity of post-Eocene records might be explained by cooling during and subsequent to the Oligocene, which was less favorable to climbers. We observe the same pattern in other megathermal families showing the global dynamic of megathermal groups of the North Hemisphere forest (boreotropical sensu. Wolfe, 1975) during the Paleogene.
•Only half of the previously reported fossil occurrences of Icacinaceae were accepted.•A great increase of diversity is shown during the Ypresian.•Most of the modern genera first appear during the early and middle Eocene.•A decrease in the diversity of the Icacinaceae is shown during the Oligocene.•Icacinaceae fit the dynamic of megathermal groups of the Northern Hemisphere forest.
Abstract
Spinescence is an important functional trait possessed by many plant species for physical defence against mammalian herbivores. The development of spinescence must have been closely ...associated with both biotic and abiotic factors in the geological past, but knowledge of spinescence evolution suffers from a dearth of fossil records, with most studies focusing on spatial patterns and spinescence-herbivore interactions in modern ecosystems. Numerous well-preserved Eocene (~39 Ma) plant fossils exhibiting seven different spine morphologies discovered recently in the central Tibetan Plateau, combined with molecular phylogenetic character reconstruction, point not only to the presence of a diversity of spiny plants in Eocene central Tibet but a rapid diversification of spiny plants in Eurasia around that time. These spiny plants occupied an open woodland landscape, indicated by numerous megafossils and grass phytoliths found in the same deposits, as well as numerical climate and vegetation modelling. Our study shows that regional aridification and expansion of herbivorous mammals may have driven the diversification of functional spinescence in central Tibetan woodlands, ~24 million years earlier than similar transformations in Africa.
Premise of research. The fossil record of Pyrenacantha (Phytocreneae tribe, Icacinaceae) includes well-documented species from the Paleogene of North and South America, but to date, no fossils have ...been described from its present geographic range, the Old World tropics. We document endocarp remains from the early Oligocene Jebel Qatrani Formation, Fayum Province, Egypt, representing the first fossil evidence of this genus from Africa. We discuss the systematic affinities of these fossils as well as their biogeographic and paleoecological implications.
Methodology. The fossil endocarps were studied by a combination of computed tomography scanning and reflected light microscopy and were extensively compared with modern fruits from multiple herbaria (representing all extant genera of Phytocreneae and numerous species of Pyrenacantha) to assess their systematic affinities. We also compared the Jebel Qatrani material with previously described Phytocreneae fossils.
Pivotal results. The Jebel Qatrani fossils conform to Pyrenacantha in their overall size, surface ornamentation (pitted), and tubercle morphology and size (tubercles are peg shaped to spiny, like the tubercles of numerous extant species of Pyrenacantha, and the tubercle length-to-diameter ratio is well above 1.0, a feature that further distinguishes Pyrenacantha from other Phytocreneae genera). However, the combination of characters shown by the Jebel Qatrani fossils is unique among modern and fossil species of Pyrenacantha, and therefore we describe them herein as a new species: P. simonsii Stull, Tiffney, Wing & Manchester, sp. nov.
Conclusions. The fossils described here indicate that Pyrenacantha has been present in Africa since at least the earliest Oligocene. Although Pyrenacantha is known from the Eocene of midlatitude North America and probably Europe, suggesting a Holarctic origin with subsequent restriction to the tropics in response to climatic cooling, the absence of older Paleogene fossils in Africa could instead reflect inadequate sampling. Given that all modern species of Pyrenacantha (and Phytocreneae in general) are climbers, we can infer that P. simonsii likely also had a climbing growth form, which is consistent with ecological interpretations of the Jebel Qatrani flora as representing at least a gallery forest if not a more widespread forest with appreciable rainfall.
PDF
