Mihai Tomescu

Background The origin of the Equisetum strobilus has long been debated and the fossil record has played an important role in these discussions. The paradigm underlying these debates has been the perspective of the shoot as node–internode alternation, with sporangiophores attached at nodes. However, fossils historically excluded from these discussions (e.g. Cruciaetheca and Peltotheca) exhibit reproductive morphologies that suggest attachment of sporangiophores along internodes, challenging traditional views. This has rekindled discussions around the evolution of the Equisetum strobilus, but lack of mechanistic explanations has led discussions to a stalemate. Scope A shift of focus from the node–internode view to a perspective emphasizing the phytomer as a modular unit of the shoot, frees the debate of homology constraints on the nature of the sporangiophore and inspires a mechanism-based hypothesis for the evolution of the strobilus. The hypothesis, drawing on data from developmental anatomy, regulatory mechanisms and the fossil record, rests on two tenets: (1) the equisetalean shoot grows by combined activity of the apical meristem, laying down the phytomer pattern, and intercalary meristems responsible for internode elongation; and (2) activation of reproductive growth programmes in the intercalary meristem produces sporangiophore whorls along internodes. Conclusions Hierarchical expression of regulatory modules responsible for (1) transition to reproductive growth; (2) determinacy of apical growth; and (3) node–internode differentiation within phytomers, can explain reproductive morphologies illustrated by Cruciaetheca (module 1 only), Peltotheca (modules 1 and 2) and Equisetum (all three modules). This model has implications – testable by studies of the fossil record, phylogeny and development – for directionality in the evolution of reproductive morphology (Cruciaetheca–Peltotheca–Equisetum) and for the homology of the Equisetum stobilus. Furthermore, this model implies that sporangiophore development is independent of node–internode identity, suggesting that the sporangiophore represents the expression of an ancestral euphyllophyte developmental module that pre-dates the evolution of leaves.

PREMISE OF THE STUDY: Diverse in modern ecosystems, mosses are dramatically underrepresented in the fossil record. Furthermore, most pre-Cenozoic mosses are known only from compression fossils, lacking detailed anatomical information. When preserved, anatomy vastly improves resolution in the systematic placement of fossils. Lower Cretaceous deposits at Apple Bay (Vancouver Island, British Columbia, Canada) contain a diverse anatomically preserved flora that includes numerous bryophytes, many of which have yet to be characterized. Among them is a polytrichaceous moss that is described here.
METHODS: Fossil moss gametophytes preserved in four carbonate concretions were studied in serial sections prepared using the cellulose acetate peel technique.
KEY RESULTS: We describe Meantoinea alophosioides gen. et sp. nov., a polytrichaceous moss with terminal gemma cups containing stalked, lenticular gemmae. Leaves with characteristic costal anatomy, differentiated into sheathing base and free lamina and bearing photosynthetic lamellae, along with a conducting strand in the stem, place Meantoinea in family Polytrichaceae. The bistratose leaf lamina with an adaxial layer of mamillose cells, short photosynthetic lamellae restricted to the costa, and presence of gemma cups indicate affinities with basal members of the Polytrichaceae, such as Lyellia, Bartramiopsis, and Alophosia.
CONCLUSIONS: Meantoinea alophosioides enriches the documented moss diversity of an already-diverse Early Cretaceous plant fossil assemblage. This is the third moss described from the Apple Bay plant fossil assemblage and represents the first occurrence of gemma cups in a fossil moss. It is also the oldest unequivocal record of Polytrichaceae, providing a hard minimum age for the group of 136 million years.

Background and Aims The evolution of complex rooting systems during the Devonian had significant impacts on global terrestrial ecosystems and the evolution of plant body plans. However, detailed understanding of the pathways of root evolution and the architecture of early rooting systems is currently lacking. We describe the architecture and resolve the structural homology of the rooting system of an Early Devonian basal lycophyte. Insights gained from these fossils are used to address lycophyte root evolution and homology. Methods Plant fossils are preserved as carbonaceous compressions at Cottonwood Canyon (Wyoming), in the Lochkovian–Pragian ($411 Ma; Early Devonian) Beartooth Butte Formation. We analysed 177 rock specimens and documented morphology, cuticular anatomy and structural relationships, as well as stratigraphic position and taphonomic conditions. Key Results The rooting system of the Cottonwood Canyon lycophyte is composed of modified stems that bear fine, dichotomously branching lateral roots. These modified stems, referred to as root-bearing axes, are produced at branching points of the above-ground shoot system. Root-bearing axes preserved in growth position exhibit evidence of positive gravitropism, whereas the lateral roots extend horizontally. Consistent recurrence of these features in successive populations of the plant preserved in situ demonstrates that they represent constitutive structural traits and not opportunistic responses of a flexible developmental programme. Conclusions This is the oldest direct evidence for a rooting system preserved in growth position. These rooting systems, which can be traced to a parent plant, include some of the earliest roots known to date and demonstrate that substantial plant–substrate interactions were under way by Early Devonian time. The morphological relationships between stems, root-bearing axes and roots corroborate evidence that positive gravitropism and root identity were evolutionarily uncoupled in lycophytes, and challenge the hypothesis that roots evolved from branches of the above-ground axial system, suggesting instead that lycophyte roots arose as a novel organ.

PREMISE OF THE STUDY: Mosses, very diverse in modern ecosystems, are currently underrepresented in the fossil record. For the pre-Cenozoic, fossil mosses are known almost exclusively from compression fossils, while anatomical preservation, which is much more taxonomically informative, is rare. The Lower Cretaceous of Vancouver Island (British Columbia, Canada) hosts a diverse anatomically preserved flora at Apple Bay. While the vascular plant component of the Apple Bay flora has received much attention, the numerous bryophytes identified at the locality have yet to be characterized.
METHODS: Fossil moss gametophytes in more than 20 carbonate concretions collected from the Apple Bay locality on Vancouver Island were studied in serial sections prepared using the cellulose acetate peel technique.
KEY RESULTS: We describe Tricosta plicata gen. et sp. nov., a pleurocarpous moss with much-branched gametophytes, tricostate plicate leaves, rhizoid bearing bases, and delicate gametangia (antheridia and archegonia) borne on specialized branches. A new family of hypnanaean mosses, Tricostaceae
fam. nov., is recognized based on the novel combination of characters of T. plicata.
CONCLUSIONS: Tricosta plicata reveals pleurocarpous moss diversity unaccounted for in extant floras. This new moss adds the first bryophyte component to an already diverse assemblage of vascular plants described from the Early Cretaceous at Apple Bay and, as the oldest representative of the Hypnanae, provides a hard minimum age for the group (136 Ma).

Fossils reported previously from the Early Silurian (Llandovery) lower Massanutten Sandstone (Virginia, USA) are formally described here as Prattella massanuttense gen. & sp. nov. Organization into cellular filaments embedded in extracellular matrix, the sizes of cells and filaments and the fluvial origin of deposits that host the fossils are all consistent with cyanobacterial affinity. Prattella massanuttense combines preservation as carbonaceous compression at a macroscopic scale with cellular preservation by mineral replacement of cell contents at a microscopic scale. These fossils provide the earliest direct evidence for the occurrence of cyanobacteria in fluvial habitats and add to the knowledge of terrestrial ecosystems that hosted early stages of land plant evolution.

Reiteration is a widespread component of plant growth whose evolutionary importance in ferns is not recognized widely. We introduce and discuss the growth architecture of Kaplanopteris clavata, a fossil filicalean fern from the Pennsylvanian (ca. 305 million yeas old), focusing on types of reiteration exhibited by this species and on the adaptive and phylogenetic significance of reiteration for ferns in general. Kaplanopteris clavata combines two types of reiterative growth where growth modules are borne on fronds: (1) entire fronds derived from primary pinnae, and (2) epiphyllous plantlets. This combination of reiterative pathways, unique among fossil and living ferns, allowed K. clavata to explore ecospace through an opportunistic combination of scrambling, climbing and epiphytic growth. Kaplanopteris clavata underscores the organographic importance of fronds (as opposed to stems) in the adaptive architecture of ferns, emphasizing functional convergences between the different Bauplane of ferns and angiosperms. This unique combination of reiterative pathways is interpreted as a derived condition illustrating the structural
and developmental complexity achieved by some filicaleans during the first major evolutionary radiation of leptosporangiate ferns.

A compression macrofossil with structure consisting of mineral-replaced filaments embedded in an amorphous carbonaceous matrix is described as a macrophytic cyanobacterial colony from continental assemblages of the Early Silurian (Llandovery)
Passage Creek biota, in the lower Massanutten Sandstone (Virginia, USA). Filaments are predominantly multiseriate and consist of spheroidal crystalline aggregates representing early pyrite (subsequently replaced by iron hydroxides) precipitated preferentially inside cells. Interpretation of the fossils as cyanobacteria is based on close similarities to modern organisms in terms of overall morphology and production of copious extracellular investments, filament and cell sizes, and continental epigeal (freshwater or terrestrial) habitat. This interpretation incorporates data on cyanobacterial taphonomy and mechanisms of diagenetic mineral precipitation. These fossils are part of the oldest macrofossil assemblages documenting well-developed and diverse communities on
continents. They provide the earliest direct evidence for cyanobacteria in strictly continental habitats, corroborating the commonly held but poorly documented view that cyanobacteria were among the initial colonizers of continents.

The Pennsylvanian filicalean fern Kaplanopteris clavata gen. et comb. nov. is reconstructed on the basis of permineralized vegetative and fertile frond segments and rhizomes. Characteristic anatomy conforming to morphospecies Anachoropteris clavata Graham allows for integration of new observations and reevaluation of material from Ohio with published data into the whole-plant reconstruction. Epiphyllous rhizomes arise laterally along frond rachides and feature terete exarch protosteles. Fronds are planar, tripinnate-pinnatifid, with alternate division. Vascular traces of all frond members have adaxial, exarch protoxylem. Rachides and primary pinnae
have adaxially convex C-shaped traces; secondary pinna traces are terete. Pinnules are laminar, with lobed margins and open dichotomous venation. Tripinnate latent croziers equivalent in complexity to whole fronds arise on otherwise mature frond segments at the position of primary pinnae. Superficial abaxial indusiate sori exhibit gradate maturation and include numerous leptosporangia producing trilete spores. Sporangial capsules are bent away from the center of the sorus at the juncture with the long, uniseriate stalks. The annulus is a band of two to three rows of interfingering cells, wrapped around the long axis of the sporangium and covering most of it. The longitudinal stomium faces toward the apex of the sorus. Kaplanopteris clavata is reconstructed as a primarily vining plant with organography overwhelmingly dominated by the frond and a unique life-history pattern influenced by growth from two types of foliar-borne reiterative units: latent croziers and rhizomes. Kaplanopteris combines characters known exclusively in fossil filicaleans with both plesiomorphic and derived characters of living filicaleans. This novel combination reveals the existence of a previously unrecognized lineage
of basal filicaleans and justifies placement in a new family. Kaplanopteris illustrates the diversity and complexity reached during the first major evolutionary radiation of filicaleans.

Cyanobacteria in terrestrial and aquatic habitats are frequently associated with heterotrophic bacteria, and such associations are most often metabolically interactive. Functionally, the members of such bacterial–cyanobacterial consortia benefit from diverse metabolic capabilities of their associates, thus exceeding the sum of their parts. Such associations may have been just as ubiquitous in the past, but the fossil record has not produced any direct evidence for such associations to date. In this paper, we document fossil bacteria associated with a macrophytic cyanobacterial mat in the early Silurian (Llandovery) Massanutten Sandstone of Virginia, USA. Both the bacterial and the cyanobacterial cells are preserved by mineral replacement (pyrite subsequently replaced by iron oxyhydroxides) within an amorphous carbonaceous matrix which represents the common exopolysaccharide investment of the cyanobacterial colony. The bacteria are rod-shaped, over 370 nm long and 100 nm in diameter, and occur both as isolated cells and as short filaments. This occurrence represents the oldest fossil evidence for bacterial–cyanobacterial associations, documenting that such consortia were present 440 Ma ago, and revealing the potential for them to be recognized deeper in the fossil record.

• Premise of the study: Morphology is a reflection of evolution, and as the majority of biodiversity that has lived on Earth is now
extinct, the study of the fossil record provides a more complete picture of evolution. This study investigates anatomically preserved bryophyte fossils from the Eocene Oyster Bay Formation of Vancouver Island. While the bryophyte fossil record is limited in general, anatomically preserved bryophytes are even more infrequent; thus, the Oyster Bay bryophytes are a particularly signifi cant addition to the bryophyte fossil record.
• Methods: Fossils occur in two marine carbonate nodules collected from the Appian Way locality on the eastern shore of Vancouver Island, British Columbia, and were prepared using the cellulose acetate peel technique.
• Key results: The fossils exhibit a novel combination of characters unknown among extinct and extant liverworts: (1) three-ranked helical phyllotaxis with underleaves larger than the lateral leaves; (2) fascicled rhizoids associated with the leaves of all three ranks; (3) Anomoclada -type endogenous branching.
• Conclusions: A new liverwort family, Appianaceae fam. nov., is established based upon the novel combination of characters.
Appiana gen. nov. broadens the known diversity of bryophytes and adds a hepatic component to one of the richest and best
characterized Eocene floras.

A perithecial ascomycete, Spataporthe taylori gen. et sp. nov., represented by >70 sporocarps is preserved by cellular permineralization in marine carbonate concretions dated at the Valanginian-Hauterivian boundary (Early Cretaceous) from Vancouver Island, British Columbia, Canada. The spheroid perithecia with lumina 330–470 mm wide and 220–320 mm high are densely distributed and entirely immersed in the tissues of a coniferous leaf. The perithecial wall consists of an outer layer of large pseudoparenchyma and an inner layer of thin filamentous nature. Perithecial necks are incompletely preserved due to taphonomic abrasion; they have a bell-shaped chamber at the base and a narrow channel, with longitudinally aligned hyphae above. The basal chamber of the neck is filled with a plug of pseudoparenchyma, which subsequently disintegrates to form a peripheral collar; periphyses are present on the basal chamber walls. A pseudoparenchymatous hymenium lines the bottom of perithecia. Asci are clavate, with thinly tapered bases, and small (30–47 mm long and 12–20 mm wide at tip), ornamented with
minute papillae. They become detached from the hymenium to float freely in the perithecium. No unequivocal ascospores were found, although smaller units are present in some of the asci. The combination of immersed perithecia with complex wall structure and a well-defined hymenium, absence of paraphyses, and persistent, detachable inoperculate asci is consistent with order Diaporthales of class Sordariomycetes. The small clavate asci are comparable to those found in family Gnomoniaceae. Perithecioid ascomata are rare in the fossil record, and bona fide perithecia are known with certainty only from the Early Devonian Rhynie Chert and Cenozoic amber.
Spataporthe taylori contributes a well-characterized Early Cretaceous occurrence, which is also the oldest to date, to the scarce fossil record of the Sordariomycetes and a second taxon to the fungal flora of the locality, which also includes a basidiomycete. As the oldest representative of the Diaporthales, Spataporthe provides a minimum age (136 Ma) for the order and a direct calibration point for studies of divergence times in the ascomycetes.

Microconchids are an extinct group of Spirorbis-like tentaculitoid tubeworms that dwelled in a variety of aquatic environments, ranging from normal marine, through brackish and hypersaline, to freshwater. An analysis of published microconchid occurrences focusing on their ecology and palaeoenvironmental distribution through geological time is conducted in order to establish the timing of microconchid
colonization of freshwater and marginal marine habitats. Microconchids originated during the Late Ordovician in shallow shelf, normal marine environments where they thrived until their extinction at the end of the Middle Jurassic (latest Bathonian). Microconchid colonization of marginal marine brackish habitats seems to have started already by the Early Silurian (Wenlock). The freshwater habitats were invaded by microconchids in the Early Devonian, nearly simultaneously in several regions (Germany, Spitsbergen, USA). Since shallow marginal marine and freshwater habitats are more unstable, especially in terms of temperature and salinity fluctuations, as well as prone to desiccation, than normal marine, shelf environments, the drivers of the colonization of these habitats by microconchids are currently incompletely understood. We hypothesize that by colonizing such environments, microconchids gained access to abundant food resources in the form of suspended organic matter delivered from the land by rivers and streams. These, combined with their biology, enabled microconchids to reproduce fast and in large numbers. Microconchids are considered to have gone extinct by the end of the Middle Jurassic (Late Bathonian). Their youngest occurrence in freshwater environments is known from the Late Triassic and it is currently not known whether microconchids continued to occupy such habitats later on in the Jurassic. All the Middle Jurassic records of microconchids come from marine settings. Thus, more focused research on Jurassic brackish and freshwater deposits worldwide is needed to check whether they may have thrived in such environments at some locations, until their hypothesized extinction.

Multiple lines of evidence indicate that Earth's land masses became green some 2.7 Ga ago, about 1 billion years after the advent of life. About 2.2 billion years later, land plants abruptly appear in the fossil record and diversify marking the onset of ecologically complex terrestrial communities that persist to the present day. Given this long history of land colonization, surprisingly few studies report direct fossil evidence of emergent vegetation prior to the continuous record of life on land that starts in the mid-Silurian (ca. 420–425 Ma ago). Here we compare stable carbon isotope signatures of fossils from seven Ordovician–Silurian (450–420 Ma old) Appalachian biotas with signatures of coeval marine organic matter and with stable carbon isotope values predicted for Ordovician and Silurian liverworts (BRYOCARB model). The comparisons support a terrestrial origin for fossils in six of the biotas analyzed, and indicate that some of the fossils represent bryophyte-grade plants. Our results demonstrate that extensive land floras pre-dated the advent of vascular plants by at least 25 Ma. The Appalachian fossils represent the oldest direct evidence of widespread colonization of continents. These findings provide a new search image for macrofossil assemblages that contain the earliest stages of land plant evolution. We anticipate they will fuel renewed efforts to search for direct fossil evidence to track the origin of land plants and eukaryotic life on continents further back in geologic time.

The complex body plan of modern vascular plants evolved by modification of simple systems of branching axes which
originated from the determinate vegetative axis of a bryophyte grade ancestor. Understanding body plan evolution and homologies has implications for land plant phylogeny and requires resolution of the specific developmental changes and their evolutionary sequence. The branched sporophyte may have evolved from a sterilized bryophyte sporangium, but prolongation of embryonic vegetative growth is a more parsimonious explanation. Research in the bryophyte model system Physcomitrella points to mechanisms regulating sporophyte meristem maintenance, indeterminacy, branching and the transition to reproductive development. These results can form the basis for hypotheses to identify and refine the nature and sequence of changes in development that occurred during the evolution of the indeterminate branched sporophyte from an unbranched bryophyte-grade sporophyte.

Paleontology yields essential evidence for inferring not only the pattern of evolution, but also the genetic basis of evolution within an ontogenetic framework. Plant fossils provide evidence for the pattern of plant evolution in the form of transformational series of structure through time. Developmentally diagnostic structural features that serve as “fingerprints” of regulatory genetic pathways also are preserved by plant fossils, and here we provide examples of how those fingerprints can be used to infer the mechanisms by which plant form and development have evolved. When coupled with an understanding of variations and systematic distributions of specific regulatory genetic pathways, this approach provides an avenue for testing evolutionary hypotheses at the organismal level that is analogous to employing bioinformatics to explore genetics at the genomic level. The positions where specific genes, gene families,
and developmental regulatory mechanisms first appear in phylogenies are correlated with the positions where fossils with the corresponding structures occur on the tree, thereby yielding testable hypotheses that extend our understanding of the role of developmental changes in the evolution of the body plans of vascular plant sporophytes. As a result, we now have new and powerful methodologies for characterizing major evolutionary changes in morphology, anatomy, and physiology that have resulted from combinations of genetic regulatory changes and that have produced the synapomorphies by which we recognize major clades of plants.

"A major real estate development required a rescue archaeology intervention in the very downtown
Bucharest, mainly between February and June 1996. A large section, 75 long and about 3 m large was
made in the street, mostly mechanically, just in the front of the National History Museum.
The archaeological rescue digging documented 12 rooms belonging to a large inn, built by a
famous Ruler of the Romanian Country (Ţara Românească), Constantin Brâncoveanu, in the last decade
of the XVIIth century. This kind of inn, of Oriental inspiration, is typical for the passage from Late Middle
Age to Modern times, and is, in fact, a complex project including hosting areas, enclosure for animals,
large storehouses, but usually churches also. Flourishing in towns with a certain demographic growth, but
with a very poor communication means, like Bucharest, the inns were supposed to gather all goods
needed by community in five months of cold and wet weather, when the road network was impracticable.
The inn functioned about 160 years, until around 1860, the internal spaces being frequently
restored, up to 7 times. Despite the fact that the landlord was unique, for its entire existence, a comparison
between the type of internal rehabilitation operations proved that the initiative was left on tenants, the
sequence type of floors (wood, bricks or vegetal cover) being unrepeatable. The use of the spaces – when
proved by micromorphological study – is also distinctive, either cooking area, workshops connected with
open fire, or even stables for sheep, for some relatively short episodes. Those 12 rooms are placed on the
western wing of the building, on the main facade, facing a major street – Podul Mogoşoaiei – studied in
the southern end of the archaeological section. The public road was made of wooden boards supported by
wooden pillars buried under the walking level, similarly with a bridge, from which the street took its
name (“pod” meaning bridge). This type of public street, made entirely of wood, is documented in wet
lowlands, where stone is not available, like Timişoara (western Romania).
The history of the place begins during the late XVth century, for which deep buried huts were
discovered. For the mid XVIth century a new type of house was in use, made of wood, relatively large and
with cellars, typical for aristocracy. In the XVIIth century this strip of land was no more a constructive
area, a little cemetery being discovered in the southern part of the trench. The layers dated between the
cellar-houses and the inn are first in which fragments of bricks and mortar were recorded, probably from
buildings in proximity.
Regarding the political history of the Romanian countries, it might be surprising that from our
discoveries Ottoman coins are missing. We found instead some Turkish pipes, a good witness of adopting
an oriental life-style.
This paper also presents the main results of the sedimentological and micromorphological study
performed on Constantin Vodă Inn archaeological site. The field study firstly considered in the analysis
of the sedimentary successions observed on the main stratigraphic profiles and the identification of the
different types of units. The main diagnostic criteria observed in the field at the macroscopic level -
texture, structure, color, nature of constituents, homogeneity and degree of compaction - allowed
establishing a typology of sedimentary facies necessary for the interpretation in terms of mechanisms of
formation, in order to identify human activities and post-abandon transformations of the accumulated
deposits. Thus, different types of construction and arrangement units, occupation units and natural
accumulations were recognized. Micromorphological analysis, at the microscopic scale, brings detailed
information on the sedimentary units and thus contributes to a better interpretation of the archaeological
levels. Extraordinary information provided by this study is the identification of sferulites, structures
indicating the presence of the domestic animals (Ovis/Capra) in spaces fitted out with a wooden floor.
The palinological expertise – the first ever done in an archaeological site from Bucharest – revealed a
predominance of a ruderal vegetation, followed by hydrophilic vegetation and lowlands trees, but not
cereals, explained by the position is in the middle of the medieval town."