Fossil Flowers Research Articles

Fossil flowers of ericalean affinity from the Late Cretaceous of Southern Sweden

Charcoalified fossil flowers of a new genus and species (Paradinandra suecica) with affinities to Ericales s.l. (sensu lato) are described from the Late Cretaceous (Santonian-Campanian) from Southern Sweden. The flowers are pentamerous, hypogynous, and actinomorphic. Aestivation of sepals and petals is imbricate-quincuncial. The androecium consists of an outer whorl with single episepalous stamens and an inner whorl with paired epipetalous stamens. Pollen is small and probably tricolpate. Three carpels form a syncarpous ovary with numerous campylotropous ovules on parietal placentae. The styles are free for most of their length. The structure of mature fruits and seeds is unknown. Clear distinction of sepals and petals, possible dehiscence of anthers by restricted slits, presence of a nectary, and the general floral construction (salverform corolla) with a canalized access to the floral center clearly indicate insect pollination of the fossil flowers. Comparisons with extant taxa demonstrate that Paradinandra suecica shares many similarities with Ericales s.l. and in particular with members of Ternstroemiaceae, Theaceae, and Actinidiaceae. However, it is neither identical to any one genus of these families nor to any of the previously described ericalean taxa from the Cretaceous and thus provides further evidence of the diversity of Cretaceous ericalean plants.

Circumscription and phylogeny of the Laurales: evidence from molecular and morphological data

The order Laurales comprises a few indisputed core constituents, namely Gomortegaceae, Hernandiaceae, Lauraceae, and Monimiaceae sensu lato, and an equal number of families that have recently been included in, or excluded from, the order, namely Amborellaceae, Calycanthaceae, Chloranthaceae, Idiospermaceae, and Trimeniaceae. In addition, the circumscription of the second largest family in the order, the Monimiaceae, has been problematic. I conducted two analyses, one on 82 rbcL sequences representing all putative Laurales and major lineages of basal angiosperms to clarify the composition of the order and to determine the relationships of the controversal families, and the other on a concatenated matrix of sequences from 28 taxa and six plastid genome regions (rbcL, rpl16, trnT-trnL, trnL-trnF, atpB-rbcL, and psbA-trnH) that together yielded 898 parsimony-informative characters. Fifteen morphological characters that play a key role in the evolution and classification of Laurales were analyzed on the most parsimonious molecular trees as well as being included directly in the analysis in a total evidence approach. The resulting trees strongly support the monophyly of the core Laurales (as listed above) plus Calycanthaceae and Idiospermaceae. Trimeniaceae form a clade with Illiciaceae, Schisandraceae, and Austrobaileyaceae, whereas Amborellaceae and Chloranthaceae represent isolated clades that cannot be placed securely based on rbcL alone. Within Laurales, the deepest split is between Calycanthaceae (including Idiospermaceae) and the remaining six families, which in turn form two clades, the Siparunaceae (Atherospermataceae-Gomortegaceae) and the Hernandiaceae (Monimiaceae s.str. [sensu stricto]-Lauraceae). Monimiaceae clearly are polyphyletic as long as they include Atherospermataceae and Siparunaceae. Several morphological character state changes are congruent with the molecular tree: (1) Calycanthaceae have disulculate tectate-columellate pollen, while their sister clade has inaperturate thin-exined pollen, with the exception of Atherospermataceae, which have columellate but meridionosulcate or disulcate pollen. (2) Calycanthaceae have two ventral ovules while their sister clade has solitary ovules. Within this sister clade, the Hernandiaceae (Lauraceae-Monimiaceae) have apical ovules, while the Siparunaceae (Atherospermataceae-Gomortegaceae) are inferred to ancestrally have basal ovules, a condition lost in Gomortega, the only lauralean genus with a syncarpous ovary. (3) Calycanthaceae lack floral nectaries (except for isolated nectarogeneous fields on the inner tepals), while their sister clade ancestrally has paired nectar glands on the filaments. Filament glands were independently lost in higher Monimiaceae and in Siparunaceae concomitant with pollinator changes away from nectar-foraging flies and bees to non-nectar feeding beetles and gall midges. (4) Disporangiate stamens with anthers dehiscing by two apically hinged valves are ancestral in Siparunaceae-(Atherospermataceae-Gomortegaceae) and evolved independently within Hernandiaceae and Lauraceae. Depending on the correct placement of Calycanthaceae-like fossil flowers, tetrasporangiate anthers with valvate dehiscence (with the valves laterally hinged) may be ancestral in Laurales and lost in modern Calycanthaceae and Monimiaceae.

Fossil flowers with Normapolles pollen from the Upper Cretaceous of southeastern North America

Three types of fossil flowers and fruits are described from the upper Santonian (Upper Cretaceous) Buffalo Creek Member of the Gaillard Formation in central Georgia, USA. The pollen of each of these new types is known from the palynological record and can be assigned to the Normapolles group, a morphologically diverse complex of angiosperm pollen characteristic of the Upper Cretaceous of eastern North America and Europe. The fossils presented here are the first known Normapolles-producing floral structures to be described from North America. One type is similar to the European species Caryanthus knoblochii whereas a second ( Bedellia pusilla Sims et al., gen. et sp. nov.) is established as a new genus and species. The third flower type is described but not named due to lack of sufficient morphological detail. Together, the North American and European genera support previous interpretations that some members of the Normapolles complex are closely related to families within the `higher' hamamelids (especially Juglandaceae, Rhoipteleaceae, Myricaceae, and Betulaceae).

Fossil Flowers and Associated Plant Fossils from the Kamikitaba Locality (Ashizawa Formation, Futaba Group, Lower Coniacian, Upper Cretaceous) of Northeast Japan

Fossil Flowers and Associated Plant Fossils from the Kamikitaba Locality (Ashizawa Formation, Futaba Group, Lower Coniacian, Upper Cretaceous) of Northeast Japan

Two new fossil flowers of magnoliid affinity from the Late Cretaceous of New Jersey

Two taxa of cupulate magnoliid fossil flowers, Cronquistiflora and Detrusandra, are described from the Late Cretaceous (Turonian, ∼90 million years before present [MYBP]) Raritan (or lower Magothy) Formation of New Jersey. The fossil taxa are represented by flowers at various stages of development, associated fragments of cup-shaped floral receptacles with attached anthers, and isolated anthers. Both taxa have laminar stamens with adaxial thecae and valvate dehiscence. Pollen is boat-shaped and foveolate in anthers associated with Cronquistiflora and spherical with reticulate ornamentation in Detrusandra. Cup-shaped receptacles are externally bracteose in both taxa. The receptacle of Cronquistiflora is broader than the campanulate one of Detrusandra. Cronquistiflora also has more carpels (∼50 in a spiral vs. ∼5 in a whorl or tight spiral). In Detrusandra the carpels are surrounded by dorsiventrally flattened structures (pistillodes?) that are remote from the attachment of the stamens near the distal rim of the receptacular cupule. Detrusandra stigmas are rounded and bilobed, while those of Cronquistiflora, although bilateral in symmetry, are somewhat peltate. The fossil taxa share prominent characters with extant cupulate magnoliids (e.g., Eupomatia, Calycanthus), but also share characters with other magnoliids including Winteraceae. These fossils represent taxa that are character mosaics relative to currently recognized families. Inclusion of these fossils in existing data matrices and ensuing phylogenetic analyses effect changes in tree topologies consistent with their mosaicism relative to modern taxa. But such analyses do not definitively demonstrate the affinities of the fossils other than illustrating that these fossils are generalized magnoliids. Additional analysis of modern and fossil magnoliids is necessary to fully appreciate the phylogenetic significance and positions of these fossil taxa. However, the results of the phylogenetic analyses do introduce the possibility that extinct taxa of Magnoliales with cupulate floral receptacles were transitional between basal angiosperms and those with tricolpate pollen. The fossils provide insights into the timing of evolution of character complexes now associated with coleopteran pollination.

Oldest known fossils of monocotyledons

The monocotyledonous angiosperm clade (class Liliopsida) includes roughly 50,000 species1 of diverse forms. The group comprises such economically noticeable plants as palms, orchids, most of the horticultural bulbs, and grasses, which include some of the most important food crops, such as maize, rice and other grains. Modern monocotyledons are diverse and dominate many habitats, but the fossil record of these plants is meagre, fossils of monocotyledonous flowers are rare, and the earliest putative monocotyledonous fossils (pollen and leaves) are all equivocal2,3. Here we describe the oldest known fossil flowers that can be definitely assigned to the Liliopsida.

Fossil Clusiaceae from the Late Cretaceous (Turonian) of New Jersey and implications regarding the history of bee pollination

The Turonian flora from Sayreville New Jersey includes one of the world's most diverse assemblages of Cretaceous angiosperm flowers. This flora is made even more interesting by its association with a large insect fauna that is preserved by charcoalification as well as in amber. Floral diversity includes numerous representatives of Magnoliidae, Hamamelididae, Rosidae, Dilleniidae, and Asteridae (Ericales sensu lato). Included are hypogynous, five-merous flowers with uniseriate hairs on the pedicels and stamens in bundles most frequently borne opposite the petals. There is considerable variation in filament length, and some filaments are branched. On some anthers, strands of residue, suggesting the former presence of a liquid of unknown nature, partially occlude the apparent zone of dehiscence. In other cases, open anthers are fully occluded by an amorphous substance. Pollen is rarely found associated with anthers, but is common on stigmatic surfaces. Pollen is prolate and tricolporate with reticulate micromorphology. The superior syncarpous ovary is five-carpellate with axile/intruded parietal placentation and numerous anatropous ovules/carpel. Ovary partitions have closely spaced, parallel ascending channels (secretory canals?), and there are apparent secretory canals/cavities in receptacles, sepals, and petals. Individual stigmas are cuneiform with a central groove and eccentrically peltate. Styles are short and fused. In aggregate, the stigmas form a secondarily peltate stigma. Seeds have a reticulate sculpture pattern, a pronounced raphe, and funicular arils with sculpture similar to the seeds. Phylogenetic analyses of several data matrices of extant taxa place this fossil in a monophyletic group with the modern genera Garcinia and Clusia within the Clusiaceae. As such, these fossils represent the earliest fossil evidence of the family Clusiaceae. Some modern Clusiaceae are notable, in particular, for their close relationship with meliponine and other highly derived bee pollinators; the fossil flowers share several characters that suggest a similar mode of pollination. This possibility is consistent with other floral and insect data from the same locality.

A NEW FOSSIL FLOWER FROM THE TURONIAN OF New Jersey: Dressiantha bicarpellata gen. et sp. nov. (Capparales)

Recent discoveries of fossil reproductive structures from deposits of the Raritan Formation in New Jersey (Turonian, Upper Cretaceous, ~90 million years BP) include a previously undescribed representative of the Order Capparales. The fossils are usually charcoalified with three-dimensional structure and excellent anatomical details. In the present contribution, we introduce a taxon represented by fossil flowers that have a combination of characters now found in the families of the Order Capparales sensu Cronquist. The fossil species is characterized by an unique suite of characters, such as the presence of a gynophore, arrangement of the sepals, unequal petal size, monothecal anthers, and a bicarpellate gynoecium, that are found in extant families of the Order Capparales. This new taxon constitutes an important addition to our understanding of Cretaceous angiosperm diversity and represents the oldest known fossil record for the Capparales. Heretofore, the oldest known capparalean was from the Late Tertiary sediments of North America.

Tylerianthus crossmanensis gen. et SP. NOV. (aff. Hydrangeaceae) from the Upper Cretaceous of New Jersey

A fossil flower with affinities to the modern families of the saxifragalean complex is described. Fossils were collected at Old Crossman Pit, Raritan Formation, New Jersey, USA. These sediments are dated on the basis of palynology as Turonian (Upper Cretaceous, ~90 million years before present). Fossils are charcoalified and preserved with exceptional three- dimensional detail. The characters observed in these flowers, when compared with those of extant flowers of several families of the saxifragalean complex, suggest a close relationship with extant members of the Saxifragaceae and Hydrangeaceae. Hypotheses on the origin of petals and staminodes and a possible mechanism of pollination are discussed. This new taxon provides additional characters in the floral morphology of the fossil saxifragoids and extends their geographical distribution in the Cretaceous to North America.

Takhtajania perrieri rediscovered

Spectacular finds of early Cretaceous fossil flowers during the past decade have fuelled a resurgence of research into the origin of flowering plants1, the “abominable mystery” that so captivated Darwin. Now Takhtajania perrieri (Capuron) Baranova & J.-F. Leroy, the only extant Africa/ Madagascar representative of the family Winteraceae, has been rediscovered in northeastern Madagascar, 85 years after its original finding. Scientists will thus once again have a ‘living fossil’ to study and place in the context of both extinct and other extant primitive angiosperms.

Fossil flowers and fruits of the Actinidiaceae from the Campanian (Late Cretaceous) of Georgia

A new genus and species of Actinidiaceae (Parasaurauia allonensis gen. et sp. nov.) are established for fossil flowers and fruits from the early Campanian (Late Cretaceous) Buffalo Creek Member of the Gaillard Formation in central Georgia, USA. The fossil flowers, which are exquisitely preserved as charcoal, have five imbricate, quincuncially arranged sepals and petals. The androecium consists of ten stamens with anthers that are deeply sagittate proximally. The gynoecium is tricarpellate, syncarpous, and has three free styles that emerge from an apical depression in the ovary. The fruit is trilocular and contains numerous ovules on intruded axile placentae. The structure of mature fruits is unknown. Comparisons with extant taxa clearly demonstrate that the affinities of Parasaurauia allonensis are with the Ericales, and particularly with the Actinidiaceae, which have been placed among the Ericales in recent cladistic analyses. Because Parasaurauia allonensis is not identical to any one genus of Actinidiaceae, or other member of the Ericales, phylogenetic relationships of the fossil were evaluated through a cladistic analysis using morphological and anatomical characters. Results of this analysis place Parasaurauia allonensis within the Actinidiaceae as sister to the extant genera Saurauia and Actinidia. Parasaurauia allonensis differs from extant Saurauia only in having ten rather than numerous stamens.

Fossil Flowers and Fruits of the Actinidiaceae from the Campanian (Late Cretaceous) of Georgia

Fossil Flowers and Fruits of the Actinidiaceae from the Campanian (Late Cretaceous) of Georgia

Cretaceous floras containing angiosperm flowers and fruits from eastern North America

A recent innovation in paleobotanical studies of the Cretaceous has been the use of bulk sediment disaggregation and sieving techniques. This approach has identified numerous Cretaceous floras that contain well-preserved plant fossil debris (“mesofloras”), and many of these have yielded abundant fossil angiosperm flowers, as well as angiosperm fruits, seeds and dispersed stamens. On the Atlantic Coastal Plain of eastern North America recent research has identified a new series of fossil floras of Campanian age from central Georgia. These form part of a rich sequence of mesofloras that range in age from early Aptian (or perhaps late Barremian) to Campanian. Detailed studies of fossil flowers from these floras have clarified the systematic relationships of Cretaceous angiosperms and identified source plants of several characteristic dispersed angiosperm pollen grains. Taxa referable to extant angiosperm families appear suddenly in the Albian and Cenomanian, and the number of extant angiosperm families that can be recognized increases rapidly through the Late Cretaceous. Based on the record of Cretaceous fossil flowers, “modernization” of angiosperm lineages occurred much earlier than had been inferred previously from studies of dispersed fossil pollen. Major extinct monophyletic “higher” taxa of Cretaceous angiosperms have not yet been recognized.

Allonia decandra: Floral remains of the tribeHamamelideae (Hamamelidaceae) from Campanian strata of southeastern USA

A single flower, detached anthers with in situ pollen grains, and isolated seeds from Campanian strata (Upper Cretaceous) of Georgia, southeastern USA, document the presence of plants assignable toHamamelidaceae in the Upper Cretaceous. The fossil flower is actinomorphic, pentacyclic and pentamerous. Irregular sepals are preserved as lobes of the floral cup, and petals are narrow, with parallel margins. The androecium has two whorls of functional stamens. Anthers are tetrasporangiate, dehisce through two valves, and have strongly elongate connective protrusions which converge over the center of the flower. The organizational and architectural features of the fossil document its affinity within subtribeLoropetalinae (Hamamelideae, Hamamelidoideae). Cladistic phylogenetic analyses using parsimony were conducted to explore the relationships between the fossil flower and extant genera of the tribeHamamelideae. The strict consensus of the four most parsimonious trees showsHamamelideae andLoropetalinae as well-supported monophyletic taxa. The fossil flower is clearly included within theLoropetalinae, and is placed as sister taxon to the southeastern Asian genusMaingaya. The occurrence of fossils assignable toLoropetalinae during the Campanian documents the existence ofHamamelidaceae with a level of floral organization and character evolution equivalent to that of extant genera, early in the evolutionary history of the family.

Virginianthus calycanthoides gen. et sp. nov.-A Calycanthaceous Flower from the Potomac Group (Early Cretaceous) of Eastern North America

We describe a new well-preserved fossil flower, Virginianthus calycanthoides gen. et sp. nov., from the Early Cretaceous (Early or Middle Albian) of Virginia. The flower is multipartite and has a distinct, deep floral cup. The perianth and androecium are borne on the rim of the floral cup and arranged in several crowded series. Reconstruction of the flower indicates that the perianth is composed of about 12 closely spaced tepals with apically directed hairs on the abaxial surface. The androecium consists of approximately 30-40 closely spaced, sessile stamens. The anthers are dithecate and tetrasporangiate, with the pollen sacs borne toward the abaxial surface. Dehiscence is extrorse through laterally hinged valves. Pollen grains are monocolpate and reticulate and resemble the previously described pollen species Clavatipollenites minutus Brenner. Sterile structures in the transition zone between androecium and gynoecium are interpreted as inner staminodes. The gynoecium is composed of approximately 18-26 carpels borne in several series on the inner surface of the hypanthium. The flower is closely comparable to extant members of the family Calycanthaceae (including Idiospermum) and constitutes the earliest documentation of calycanthoid features in the fossil record. Differences from extant Calycanthaceae are mainly in details of the pollen sacs, anther dehiscence, and pollen morphology.

Fossil flowers and pollen ofLauraceae from the Upper Cretaceous of New Jersey

A fossil trimerous flower from the Turonian (ca. 90 MYBP, Upper Cretaceous) of New Jersey is described as a new genus in the familyLauraceae. The fossil flower is charcoalified and preserved in exceptional detail. This fossil specimen is particularly remarkable in that several pollen grains have been preserved; pollen grains ofLauraceae generally have very thin exine and are rarely preserved in the fossil record. Although the specimen is incomplete and lacks anthers, there are sufficient structural details preserved to permit an assignment to theLauraceae, as well as comparisons with the tribePerseeae. This new genus provides an important addition to our knowledge of systematic and structural diversity in CretaceousLauraceae.

Late Cretaceous Fossil Flowers of Ericalean Affinity

Fossilized flowers of ericalean affinity are reported from the Turanian (ca. 90 MYBP, million years before present) of New Jersey. The fossils are remarkably well preserved and three-dimensional, and are the oldest known floral remains of Ericales. The series of fossil flower buds, floral fragments, and fruits are not identical to any modern genus of Ericales. The inverted U-shaped anthers with pseudoterminal awns, and the fluted syncarpous ovary of the fossils suggest affinities with basal Ericaceae, probably near extant Enkianthus, a taxon that also shares monadinous pollen with the fossil. Pollen grains were observed clumped on a stigma in one of the fossil flowers. Fossilized acid-resistant strands having characteristics, including similar diameter and sculpture pattern, in common with the muri connect pollen grains and, with scanning electron microscopy, appear continuous with the tectum, supporting the interpretation that they are viscin threads. These are the oldest reported fossilized viscin threads, and the only fossilized viscin threads found in situ in flowers. In modern Ericales and Onagraceae, the presence of viscin threads is associated with highly specific plant-pollinator relationships, raising the possibility that such specific pollinator-plant relationships had developed by the mid-Cretaceous. This is consistent with floral characters in these ericalean fossils, the presence of advanced meliponine bees in slightly younger sediments from the same region, and with the morphology and affinities of other fossil flowers from the same sediments.

LATE CRETACEOUS FOSSIL FLOWERS OF ERICALEAN AFFINITY

Fossilized flowers of ericalean affinity are reported from the Turanian (ca. 90 MYBP, million years before present) of New Jersey. The fossils are remarkably well preserved and three‐dimensional, and are the oldest known floral remains of Ericales. The series of fossil flower buds, floral fragments, and fruits are not identical to any modern genus of Ericales. The inverted U‐shaped anthers with pseudoterminal awns, and the fluted syncarpous ovary of the fossils suggest affinities with basal Ericaceae, probably near extant Enkianthus, a taxon that also shares monadinous pollen with the fossil. Pollen grains were observed clumped on a stigma in one of the fossil flowers. Fossilized acid‐resistant strands having characteristics, including similar diameter and sculpture pattern, in common with the muri connect pollen grains and, with scanning electron microscopy, appear continuous with the tectum, supporting the interpretation that they are viscin threads. These are the oldest reported fossilized viscin threads, and the only fossilized viscin threads found in situ in flowers. In modern Ericales and Onagraceae, the presence of viscin threads is associated with highly specific plant‐pollinator relationships, raising the possibility that such specific pollinator‐plant relationships had developed by the mid‐Cretaceous. This is consistent with floral characters in these ericalean fossils, the presence of advanced meliponine bees in slightly younger sediments from the same region, and with the morphology and affinities of other fossil flowers from the same sediments.

Oldest fossil flowers of hamamelidaceous affinity, from the Late Cretaceous of New Jersey

Oldest fossil flowers of hamamelidaceous affinity, from the Late Cretaceous of New Jersey

Oldest fossil flowers of hamamelidaceous affinity, from the Late Cretaceous of New Jersey.

Exceptionally well-preserved staminate inflorescences, pistillate inflorescences, and detached stamens with important phylogenetic and paleoecological implications have been discovered from the Turonian (ca. 88.5-90.4 million years B.P.) Raritan Formation of New Jersey. The fossils have a combination of floral and pollen characters found in various genera of modern entomophilous and anemophilous Hamamelidaceae and anemophilous Platanus (Platanaceae). The floral characters of the fossils, including a sepal cup, staminal tube, and apparently nectariferous staminodes, indicate that this taxon was probably insect pollinated. The juxtaposition of character complexes in an extinct taxon from disparate modern taxa provides an interesting phylogenetic perspective on the origins of Hamamelidaceae and is a striking example of a fossil that is a mosaic of familial level characters relative to modern taxa. Of even broader interest, however, is the occurrence of staminodal nectaries that have structural characters intermediate between the fossil's functional stamens and modern hamamelidaceous petals. This transitional staminode morphology in the context of the other fossil characters suggests a staminodal origin of petals in the hamamelid-rosid lineage. This hypothesis is supported by the apparent staminode position within the fossil flowers where petals are found in modern genera. The character complex of morphologically transitional staminodes, a staminal tube, and sepal cup can be viewed as prehypanthial, lacking only fusion of the staminal tube to the sepal cup. The appearance of the character complex embodied in these flowers during the late mid-Cretaceous may signal the early stages of the relationship between specialized pollinators, such as bees, and the hamamelid-rosid-asterid lineage of angiosperms, arguably one of the most important events in angiosperm radiation.