Paleoaltingia gen. nov., a new genus of Altingiaceae from the Late Cretaceous of New Jersey.

PREMISE: Altingiaceae is a small family with a bimodal Northern Hemisphere distribution in eastern North America and eastern Asia, and a rich Cenozoic fossil record. The charcoalified fossil infructescence Paleoaltingia gen. nov. from Turonian (Late Cretaceous) deposits of New Jersey, provides new evidence of early Altingiaceae reproductive structures and has biogeographical implications in understanding modern distribution. METHODS: Fossils were prepared using standard methods for obtaining and processing mesofossils. The fossils were examined with light microscopy, and scanning electron microscopy for observing structural and anatomical details. Phylogenetic analyses were performed using a combined matrix of molecular and morphological data. RESULTS: Based on morphological features of the fossil and the phylogenetic analyses, the new genus, Paleoaltingia, with two species (Paleoaltingia ovum-dinosauri and P. polyodonta) is erected. The phylogenetic position of Paleoaltingia confirms affinities with living Altingiaceae. CONCLUSIONS: The combination of characters-simple capitate infructescence, syncarpous bicarpellate, and bilocular ovary, unique sterile phyllome structures-indicates that the fossil taxa have close affinities to modern Altingiaceae. The unique characters of the phyllomes provide new information on the floral diversity of Altingiaceae. The emergence of Paleoaltingia in Late Cretaceous sediments of Northeastern North America represents the earliest fossil record of Altingiaceae and provides new insights into its biogeography.

Morphological (and not anatomical or reproductive) features define early vascular plant phylogenetic relationships.

PREMISE: Perhaps the most rapid period of vascular plant evolution occurred during the Silurian-Devonian time interval. Yet, few quantitative analyses have established the extent to which anatomical, morphological, or reproductive features contributed to this episode of tracheophyte diversification. METHODS: Phylogenetic analyses were performed using a newly revised matrix of 54 characters (with 158 character states) of 37 of the best-preserved Paleozoic (predominantly Devonian) plants. Equisetum was included to determine whether it aligns with fossil sphenopsids or taxa collectively considered "ferns". The topology of the 54-character consensus tree was then compared to the topologies generated using only reproductive features (18 characters; 47 character states), only anatomical features (14 characters; 54 character states), only morphological features (22 characters; 57 character states), and the three pairwise combinations (e.g., anatomical and morphological characters). RESULTS: The new 54-character tree topology continued to identify a trimerophyte-euphyllophyte clade and a zosterophyllophyte-lycophyte clade emerging from a Cooksonia-rhyniophyte plexus. Equisetum aligned with fossil sphenopsids rather than fern-like fossil taxa. Reproductive characters or anatomical characters analyzed in isolation resulted in nearly complete polytomy. Among the various permutations of the three categories, anatomical and morphological characters when combined provided the best restoration of the 54-character tree topology. CONCLUSIONS: The phylogenetic relationships among the canonical fossil taxa used in this analysis predominantly reflect morphological trends. Reproductive and anatomical features taken in isolation appear to be evolutionarily conservative characters, i.e., natural selection "sees" the external phenotype.

Cretaceous asterid evolution: fruits of Eydeia jerseyensis sp. nov. (Cornales) from the upper Turonian of eastern North America.

BACKGROUND AND AIMS: The asterids (>80 000 extant species) appear in the fossil record with considerable diversity near the Turonian-Coniacian boundary (~90 Ma; Late Cretaceous) and are strongly represented in the earliest diverging lineage, Cornales. These early asterid representatives have so far been reported from western North America and eastern Asia. In this study, we characterize a new cornalean taxon based on charcoalified fruits from the upper Turonian of eastern North America, a separate landmass from western North America at the time, and identify early palaeobiogeographical patterns of Cornales during the Cretaceous. METHODS: Fossils were studied and imaged using scanning electron microscopy and micro-computed tomography (micro-CT) scanning. To assess the systematic affinities of the fossils, phylogenetic analyses were conducted using maximum parsimony. KEY RESULTS: The charcoalified fruits are represented by tri-locular woody endocarps with dorsal apically opening germination valves. Three septa intersect to form a robust central axis. Endocarp ground tissue consists of two zones: an outer endocarp composed of isodiametric sclereids and an inner endocarp containing circum-locular fibres. Central vasculature is absent; however, there are several small vascular bundles scattered within the septa. Phylogenetic analysis places the new taxon within the extinct genus Eydeia. DISCUSSION: Thick-walled endocarps with apically opening germination valves, no central vascular bundle and one seed per locule are indicative of the order Cornales. Comparative analysis suggests that the fossils represent a new species, Eydeia jerseyensis sp. nov. This new taxon is the first evidence of Cornales in eastern North America during the Cretaceous and provides insights into the palaeobiogeography and initial diversification of the order.

Mid-Cretaceous angiosperm radiation and an asterid origin of bilaterality: diverse and extinct "Ericales" from New Jersey.

PREMISE OF THE STUDY: Numerous fossils from the Upper Cretaceous have been confidently placed within modern crown groups. Many 95-75 Myr-old taxa, however, including the taxon described herein, do not fit well with known extant crown or stem groups. Understanding such fossils and their possible affinities would certainly enhance our understanding of the circumstances involved in a major eudicot radiation. METHODS: Bulk samples from the Old Crossman Clay Pit were prepared using standard methodology, which includes several washing and sieving steps, and a treatment with hydrofluoric acid. The fossil taxon was coded into a matrix built from the combination of two previously published morphological matrices and was analyzed using the parsimony criterion with the computer program TNT. KEY RESULTS: The fossils have a unique combination of characters relative to living and fossil Ericales taxa, and therefore, a new genus, Teuschestanthes, is erected. Mosaic evolution and rapid parallel changes in such groups blur taxonomic distinctions, and these issues are exacerbated by limited numbers of characters available in fossils. Teuschestanthes flowers are slightly bilaterally symmetrical and somewhat variable with regard to petal disposition, suggesting an early stage in transition to bilaterality from radial symmetry early in eudicot history under pollinator selective pressure. CONCLUSIONS: While Teuschestanthes shares characters with modern Ericales and Sapindales, there are significant non-overlapping differences between Teuschestanthes and modern Sapindales (notably, among others, ovule number). Based on available evidence, however, the position of Teuschestanthes is likely as an early offshoot of the stem clade of core Ericales (Ericales sensu stricto). Its relatively unstable floral plan may presage subsequent bilaterality associated with growing selective pressure by advanced pollinators.

A late Cretaceous fagalean inflorescence preserved in amber from New Jersey.

PREMISE OF THE STUDY: An inflorescence with three pistillate flowers in amber from the early Upper Cretaceous (Turonian, ~90-94 million years ago) of central New Jersey represents the oldest known flowers with features present in an early stem complex of the Fagales. The inflorescence has characteristics of Nothofagaceae, but also has strikingly distinct characters that suggest it is intermediate between Nothofagus and other Fagales. This intermediacy is consistent with its northern hemisphere distribution. METHODS: We investigated this new fossil by comparing it with extant and fossil members of the Fagales using light microscopy and nano-computed tomography. In addition, for exploring its relationships, we mapped the morphological characters onto a widely accepted molecular-based tree of modern basal Fagales using standard methods of character optimization. KEY RESULTS: The phylogenetic position of the fossil inflorescence can be unequivocally determined by the presence of unique features, singly and in combination, that are found only in "basal" members of Fagales. The fossil adds critical information on the features of the early stem Fagales, evolution of the cupule in Nothofagaceae and Fagaceae, and a reasonable biogeographic hypothesis for the differentiation of southern (e.g., Nothofagaceae) and northern hemisphere Fagales. CONCLUSIONS: This new fossil provides insight into the early evolution of Fagales and suggests that early stem Fagales that had not yet differentiated into modern families were present in the Late Cretaceous of North America. Based on available evidence, the fossil is best interpreted as an early stem member of the Fagales, with features that suggest a transition from a more generalized Nothofagus-like fagalean ancestor with some unique presumably plesiomorphic features. The presence of an enlarged perianth and flexuous styles also suggests the possibility of insect pollination, which has been lost in all Fagales with the exception of some members of subfamily Castaneoideae in Fagaceae sensu stricto (which otherwise are very different from this fossil). The poorly developed, bract-like cupule valves of the fossil can be interpreted as primitive (i.e., incipient) or as reduced from more developed cupules that are found in most modern Fagaceae and Nothofagaceae.

A mosaic Lauralean flower from the Early Cretaceous of Myanmar.

PREMISE OF THE STUDY: The floral history of early angiosperms is far from complete. The fossil discussed here has the potential to expand our knowledge of timing, reproductive biology, and paleobiogeography in early angiosperms. METHODS: Cutting-edge methodologies in CT scanning in conjunction with tomography software have opened new possibilities for discovering details in amber-preserved fossils that were inaccessible for meaningful study in the past. KEY RESULTS: The fossil is small and complex, cupulate, with numerous stamens and a suite of characters distributed in the modern families of Laurales. The most parsimonious placement of the fossil based on morphology is as a sister taxon of Atherospermataceae + Gomortega (Gomortegaceae). CONCLUSIONS: This fossil taxon, a Laurasian Lauralean from the mid-Cretaceous, is an important example of fossil Laurales with implications for biogeography and timing in the radiation and extinction in this group.

Is the anthophyte hypothesis alive and well? New evidence from the reproductive structures of Bennettitales.

Bennettitales is an extinct group of seed plants with reproductive structures that are similar in some respects to both Gnetales and angiosperms, but systematic relationships among the three clades remain controversial. This study summarizes characters of bennettitalean plants and presents new evidence for the structure of cones and seeds that help clarify relationships of Bennettitales to flowering plants, Gnetales, and other potential angiosperm sister groups. Bennettitales have simple mono- or bisporangiate cones. Seeds are borne terminally on sporophylls. They have a unique structure that includes a nucellus with a solid apex, no pollen chamber, and a single integument, and they are clearly not enclosed by a cupule or other specialized structures. Such features differ substantially from Gnetales, flowering plants, and the seed fern Caytonia, providing no compelling evidence for the origin of the angiospermous carpel. Cladistic tests were performed to assess the strength of the "anthophyte hypothesis" and possible relationships of Bennettitales, Gnetales, and Caytonia to flowering plants. Our results do not support the anthophyte hypothesis for the origin of angiosperms by a transformation of fertile organs that were already aggregated into a cone or flower-like structure. However, the anthophyte topology of the seed plant tree continues to be supported by morphological analyses of living and extinct taxa.

Darwin's second 'abominable mystery': Why are there so many angiosperm species?

The rapid diversification and ecological dominance of the flowering plants beg the question "Why are there so many angiosperm species and why are they so successful?" A number of equally plausible hypotheses have been advanced in response to this question, among which the most widely accepted highlights the mutually beneficial animal-plant relationships that are nowhere better developed nor more widespread than among angiosperm species and their biotic vectors for pollination and dispersal. Nevertheless, consensus acknowledges that there are many other attributes unique to or characteristic of the flowering plants. In addition, the remarkable coevolution of the angiosperms and pollination/dispersal animal agents could be an effect of the intrinsic adaptability of the flowering plants rather than a primary cause of their success, suggesting that the search for underlying causes should focus on an exploration of the genetic and epigenetic mechanisms that might facilitate adaptive evolution and speciation. Here, we explore angiosperm diversity promoting attributes in their general form and draw particular attention to those that, either individually or collectively, have been shown empirically to favor high speciation rates, low extinction rates, or broad ecological tolerances. Among these are the annual growth form, homeotic gene effects, asexual/sexual reproduction, a propensity for hybrid polyploidy, and apparent "resistance" to extinction. Our survey of the literature suggests that no single vegetative, reproductive, or ecological feature taken in isolation can account for the evolutionary success of the angiosperms. Rather, we believe that the answer to Darwin's second "abominable mystery" lies in a confluence of features that collectively make the angiosperms unique among the land plants.

Pentapetalum trifasciculandricus gen. et sp. nov., a thealean fossil flower from the Raritan Formation, New Jersey, USA (Turonian, Late Cretaceous).

The study of fossil flowers in the last 25 years has greatly increased our understanding of angiosperm diversification. Following that tradition, we here describe a new fossil taxon from the Late Cretaceous of New Jersey, Pentapetalum trifasciculandricus Martínez-Millán, Crepet et Nixon gen. et sp. nov. It includes actinomorphic pentamerous flowers with quincuncial calyx, imbricate corolla, numerous stamens of markedly different heights, and a superior tricarpellate ovary, which are morphologically consistent with the flowers of the Theaceae s.l. and of members of the order Theales sensu Cronquist. Cladistic analyses including 45 extant taxa plus the fossil, 61 morphological characters, and different combinations of the molecular markers rbcL, matK, trnL-trnF, matR, and ITS support its inclusion in the order Ericales sensu APG. Comparison with extant taxa using traditional methods of identification suggests a relation with the Theaceae s.s. (Stewartia), but the phylogenetic analyses do not support this view. Instead, the phylogenetic analysis suggests some relation to the Ternstroemiaceae/Pentaphylacaceae (Theaceae s.l.), exemplifying the importance of evaluating identifications in a phylogenetic context. The description of Pentapetalum further adds to the ample diversity of Ericales in the Late Cretaceous.

An extinct calycanthoid taxon, Jerseyanthus calycanthoides , from the Late Cretaceous of New Jersey.

A new fossil genus and species, Jerseyanthus calycanthoides, is described from the Late Cretaceous (Turonian, ∼90 MYBP) Raritan Formation of New Jersey. Flowers have cupulate receptacles bearing imbricately arranged tepals that subtend a series of recurved tepals near the cup margin. Recurved tepal subtends a "stamen-staminode" pair, that includes a laminar stamen with ramified connective extensions, and an outer staminode. Outer staminodes are geniculate and incurved, and in aggregate their inner extremities define a circular area above the carpels and carpellodes. Each "stamen-staminode" pair apparently subtends (is opposite to) an inner tepal. Pollen is rounded and disulculate, with tectate columellate wall structure. Carpels are located at the center of the receptacle and have elongate styles that extend to and beyond the opening defined by the staminodal organs. Carpels are surrounded by tomentose carpellodes. Carpels include one marginally ridged seed. While these fossils do not match exactly any living species in morphology, they share numerous characters with extant members of Calycanthaceae and can be unequivocally placed within that family. Affinities of Jerseyanthus and Virginianthus were evaluated by including them in a combined analysis for the Laurales. Jerseyanthus is placed within Calycanthaceae as a sister taxon to the modern genus Calycanthus.

Fossil evidence and phylogeny: the age of major angiosperm clades based on mesofossil and macrofossil evidence from Cretaceous deposits.

The fossil record has played an important role in the history of evolutionary thought, has aided the determination of key relationships through mosaics, and has allowed an assessment of a number of ecological hypotheses. Nonetheless, expectations that it might accurately and precisely mirror the progression of taxa through time seem optimistic in light of the many factors potentially interfering with uniform preservation. In view of these limitations, attempts to use the fossil record to corroborate phylogenetic hypotheses based on extensive comparisons among extant taxa may be misplaced. Instead we suggest a method-minimum age node mapping-for combining reliable fossil evidence with hypotheses of phylogeny. We use this methodology in conjunction with a phylogeny for angiosperms to assess timing in the history of major angiosperm clades. This method places many clades both with and without fossil records in temporal perspective, reveals discrepancies among clades in propensities for preservation, and raises some interesting questions about angiosperm evolution. By providing a context for understanding the gaps in the angiosperm fossil record this technique lends credibility and support to the remainder of the angiosperm record and to its applications in understanding a variety of aspects of angiosperm history. In effect, this methodology empowers the fossil record.

Divisestylus gen. nov. (aff. Iteaceae), a fossil saxifrage from the Late Cretaceous of New Jersey, USA.

Fossilized flowers and fruits from the Upper Cretaceous (Turonian, ca. 90 million years [my] before present) Raritan Formation of New Jersey are described as the new genus Divisestylus with two species, D. brevistamineus and D. longistamineus. The fossils are fusainized and three-dimensionally preserved. Morphological characteristics suggest affinities with extant Saxifragaceae and Iteaceae, two closely related families in Saxifragales. Similarities include a pentamerous perianth, calyx fused below into a hypanthium with free sepal lobes above, haplostemonous androecium with stamens situated opposite the calyx lobes, inferior ovary, bicarpellate gynoecium, numerous ovules on axile placentas, conspicuous intrastaminal nectary ring, and capsulate fruit opening apically. The unique fusion of the gynoecium, with carpels and stigmas fused but styles free, indicates closer affinities with extant Iteaceae, whereas other characters, such as basifixed anthers in D. brevistamineus, tricolpate and striate pollen grains, and anomocytic stomata, indicate closer affinities to Saxifragaceae. Cladistic analyses utilizing molecular data from a previously published analysis and morphological data as well as morphological data alone demonstrate the fossils share a more recent common ancestor with Iteaceae than Saxifragaceae, thereby making Divisestylus the oldest fossils known with clear affinities to Iteaceae.

Triuridaceae fossil flowers from the Upper Cretaceous of New Jersey.

We report here on a series of fossil flowers exhibiting a mosaic of characters present in the extant monocot family Triuridaceae. Phylogenetic analyses of morphological data from a broad sample of extant monocots confirm the affinities of the fossils with modern Triuridaceae. The fossil flowers were collected from outcrops of the Raritan Formation (Upper Cretaceous, ∼90 million years before present), New Jersey, USA. These are the oldest known unequivocal monocot flowers. Because other reports of "earliest" monocots are all based on equivocal character suites and/or ambiguously preserved fossil material, the Triuridaceae fossils reported here should also be considered as the oldest unequivocal fossil monocots. Flowers are minute and unisexual (only male flowers are known); the perianth is composed of six tepals, lacking stomata. The unicyclic androecium is of three stamens with dithecal, monosporangiate, extrorse anthers that open by longitudinal slits. The endothecium has U-shaped type thickenings. Pollen grains are monosulcate. The triurid fossil flowers can be separated into three distinctive species. On the basis of phylogenetic analyses of morphological characters, the fossil taxa nest within the completely saprophytic achlorophyllous Triuridaceae supporting the interpretation that the extinct plants were also achlorophyllous and saprophytic. If so, this represents the earliest known fossil occurrence of the saprophytic/mycotrophic habit in angiosperms.