Hans Kerp

Fossil arbuscular mycorrhizae from the early Devonian

AbstractThe 400 million-year-old Rhynie chert has provided a wealth of information not only of early land plants, but also of the fungi that inhabited this paleoecosystem. In this paper we report t...

Fungi from the Rhynie chert: a view from the dark side

The exquisite preservation of organisms in the Early Devonian Rhynie chert ecosystem has permitted the documentation of the morphology and life history biology of fungi belonging to several major taxonomic groups (e.g., Chytridiomycota, Ascomycota, Glomeromycota). The Rhynie chert also provides the first unequivocal evidence in the fossil record of fungal interactions that can in turn be compared with those in modern ecosystems. These interactions in the Rhynie chert involve both green algae and macroplants, with examples of saprophytism, parasitism, and mutualism, including the earliest mycorrhizal associations and lichen symbiosis known to date in the fossil record. Especially significant are several types of specific host responses to fungal infection that indicate that these plants had already evolved methods of defence similar and perhaps analogous to those of extant plants. This suggests that mechanisms underlying the establishment and sustenance of associations of fungi with land plants were well in place prior to the Early Devonian. In addition, a more complete understanding of the microbial organisms involved in this complex ecosystem can also provide calibration points for phylogenies based on molecular data analysis. The richness of the microbial community in the Rhynie chert holds tremendous potential for documenting additional fungal groups, which permits speculation about further interactions with abiotic and biotic components of the environment.

How Paleozoic Vines and Lianas Got off the Ground: On Scrambling and Climbing Carboniferous–Early Permian Pteridosperms

Late Paleozoic pteridosperms displayed various growth habits, including arborescent, leaning, and scrambling and/or climbing forms. This article reviews information gathered to date on vine- and liana-like forms among these plants, based on impression/compression material and cuticle preparations from the Upper Carboniferous and Lower Permian of Europe and North America. Vine- and liana-like pteridosperms used various modes of attachment for both anchorage and support. Such adaptations are very similar (and perhaps analogous) to those that exist in extant angiosperms and include hooks, leaflet tendrils, tendrils terminating in adhesive pads, and aerial adventitious roots. A number of morphological features of scrambling/climbing pteridosperms (e.g., tiny, deeply sunken stomata, marginal water pits, various types of secretory structures, and heterophylly) are considered as they relate to the autecological significance where they may be related to special physiological requirements necessary in the scrambling/climbing growth habit. We hypothesize that scrambling and/or climbing pteridosperms may have played an important role in some of the late Paleozoic coal-swamp forest ecosystems, perhaps even comparable to the role of angiospermous vines/lianas in tropical and subtropical forest ecosystems today.ZusammenfassungJungpaläozoische Pteridospermen besaßen unterschiedliche Wuchsformen; einige Taxa waren freistehende Bäume, andere Formen stützten ihre Körper durch Anlehnen, wieder andere waren Spreizklimmer oder Kletterpflanzen. Die vorliegende Arbeit gibt eine Übersicht über Spreizklimmer und Kletterer unter den Abdrucktaxa oberkarbonischer und unterpermischer Pteridospermen aus Europa und Nordamerika. Anhand von Abdruckfossilien und Kutikulapräparationen kann demonstriert werden, daß spreizklimmende/kletternde Pteridospermen verschiedene Kletterhilfen (z.B. Haken, Blattfadenranken, Haftscheibenranken, Adventivwurzeln) zur Verankerung ihrer Körper an Stützen ausbildeten, die denen heutiger spreizklimmender/kletternder Angiospermen sehr ähnlich sind und vielleicht analoge Bildungen darstellen. Auffällige Merkmale spreizklimmender/kletternder Pteridospermen (z.B. winzige, tief eingesenkte Stomata, marginale Wassergruben, verschiedene Sekretionseinrichtungen, Heterophyllie) werden im Zusammenhang mit ihrer möglichen ökologischen Bedeutung diskutiert—einige stellen offensichtlich Adaptationen an die besonderen Anforderungen und Limitationen der spreizklimmenden/kletternden Lebensweise dar. Wir vermuten, daß spreizklimmende und kletternde Pteridospermen in einigen jungpaläozoischen Sumpfwald-Ökosystemen eine wichtige Rolle gespielt haben, die vielleicht sogar mit der Rolle spreizklimmender und kletternder Angiospermen in heutigen tropischen und subtropischen Waldökosystemen vergleichbar ist.

Typical Triassic Gondwanan floral elements in the Upper Permian of the paleotropics

Permian floras of the Middle East often show a mixture of Euramerican, Cathaysian, and Gondwanan elements. We report several species of Dicroidium , a seed fern typical for the Triassic of Gondwana, from the Upper Permian of the Dead Sea region. This is the earliest unequivocal record and the most northerly occurrence of this genus, suggesting that it may have evolved during the Permian in the paleotropics. With the decline and eventual extinction of the typical Permian Glossopteris flora, Dicroidium may have migrated southward. As the climate ameliorated in the Triassic, Dicroidium could have spread farther, eventually colonizing all of Gondwana, where it became one of the dominant floral elements.

A harvestman (Arachnida: Opiliones) from the Early Devonian Rhynie cherts, Aberdeenshire, Scotland

A harvestman (Arachnida: Opiliones) is described from the Early Devonian (Pragian) Rhynie cherts, Aberdeenshire, Scotland. Eophalangium sheari gen. et sp. nov. is the oldest known harvestman. The material includes both males and a female preserving, respectively, a cuticle-lined penis and ovipositor within the opisthosoma. Both these structures are of essentially modern appearance. The Rhynie fossils also show tracheae which are, again, very similar to those of living harvestmen. This is the oldest unequivocal record of arachnid tracheal respiration and indicates that E. sheari was terrestrial. An annulate, setose ovipositor in the female suggests that it can be excluded from the clades Dyspnoi and Laniatores, in which the ovipositor lacks such annulations. However, the penis shows evidence of two muscles, a feature of uncertain polarity seen in modern Troguloidea (Dyspnoi). The presence of median eyes and long legs excludes Cyphophthalmi, and thus, E. sheari is tentatively referred to the suborder Eupnoi. Therefore, this remarkable material is implicitly a crown-group harvestman and is one of the oldest known crown-group chelicerates. It also suggests an extraordinary degree of morphological stasis within the eupnoid line, with the Devonian forms differing little in gross morphology – and perhaps in reproductive behaviour – from their modern counterp

Mesozoic seed ferns: Old paradigms, new discoveries1

Abstract Taylor, E. L., T. N. Taylor (Department of Ecology and Evolutionary Biology, and Natural History Museum and Biodiversity Research Center, 1200 Sunnyside Ave., University of Kansas, Lawrence, KS 66045), H. Kerp (Forschungsstelle für Paläobotanik, Westfälische Wilhelms-Universität Münster, Hindenburgplatz 57, D-48143 Münster, Germany), and E.J. Hermsen (Department of Ecology and Evolutionary Biology, and Natural History Museum and Biodiversity Research Center, 1200 Sunnyside Ave., University of Kansas, Lawrence, KS 66045). J. Torrey Bot. Soc. 133: 62–82. 2006.—Mesozoic seed ferns represent a grade of gymnospermous plants whose affinities remain problematic. The three major orders recognized today include the Caytoniales (Triassic-Cretaceous), Peltaspermales (Carboniferous-Triassic) and Corystospermales (Triassic-Cretaceous). A number of genera described from Mesozoic rocks have also been included broadly in the Mesozoic seed ferns, but their frequency, distribution, and affinities render their assignment to specific orders equivocal. The morphotypes in the three principal orders have been important in phylogenetic analyses of seed plants and have been implicated as angiosperm progenitors at various times in the past. All three groups were originally described only from compression/impression fossils, but anatomically preserved corystosperms are now known from Argentina and Antarctica. Since their original description, the geographic and stratigraphic ranges of all three major groups have been expanded, and they are now known from both the northern and southern hemispheres. An additional order of Mesozoic seed ferns, the Petriellales, has been described from the Triassic of Antarctica. This paper will summarize our current knowledge of the Mesozoic seed ferns and comment on the phylogenetic position of several orders, focusing especially on permineralized and compressed corystosperms from the Triassic of Antarctica. Recent studies of well-preserved material from the central Transantarctic Mountains have provided information about the three-dimensional morphology and anatomy of pollen organs and ovulate cupules, as well as the first evidence of the attachment of reproductive organs to the parent plant. These discoveries offer new information that can be used in phylogenetic analyses to provide increased resolution of seed plant relationships.

Fossil insect eggs and ovipositional damage on bennettitalean leaf cuticles from the Carnian (Upper Triassic) of Austria

Abstract Two types of evidence for insect ovipositional activity (i.e., actual egg chorions and ovipositional damage) occur on Nilssoniopteris (bennettitalean foliage) leaf cuticles from the Carnian of Austria and provide a rare direct insight into insect egg morphology and oviposition in the Late Triassic. The egg chorions have exclusively been found on N. haidingeri leaves, where they are attached to the outer surface of the abaxial cuticle; one specimen suggests that the eggs were arranged in circles. It is impossible at present to determine the affinities of the eggs; possible producers may be beetles, dragonflies, sawflies, or other allied basal Hymenoptera. Ovipositional damage occurs on N. angustior leaves in the form of lenticular egg impressions surrounded by a narrow, elevated margin. The impressions are visible on the ad- and abaxial cuticle, and coincide when both cuticles are superimposed, which indicates that the eggs producing these impressions were injected into the interior of the leaf. Producers of eggs that may have caused these damages are perhaps dragonflies or damselflies. The restricted occurrence of the two types of ovipositional activity suggests that some kind of host specificity existed, perhaps related to specific preferences in larval diet.

Microanatomy of Early Devonian book lungs

The book lungs of an exceptionally preserved fossil arachnid (Trigonotarbida) from the Early Devonian (approx. 410 Myr ago) Rhynie cherts of Scotland were studied using a non-destructive imaging technique. Our three-dimensional modelling of fine structures, based on assembling successive images made at different focal planes through the translucent chert matrix, revealed for the first time fossil trabeculae: tiny cuticular pillars separating adjacent lung lamellae and creating a permanent air space. Trabeculae thus show unequivocally that trigonotarbids were fully terrestrial and that the microanatomy of the earliest known lungs is indistinguishable from that in modern Arachnida. A recurrent controversy in arachnid evolution is whether the similarity between the book lungs of Pantetrapulmonata (i.e. spiders, trigonotarbids, etc.) and those of scorpions is a result of convergence. Drawing on comparative studies of extant taxa, we have identified explicit characters (trabeculae, spines on the lamellar edge) shared by living and fossil arachnid respiratory organs, which support the hypothesis that book lungs were derived from a single, common, presumably terrestrial, ancestor.

New gametophytes from the Early Devonian Rhynie chert

Several new gametophytes are described from the Early Devonian Rhynie chert. The new monotypic genus Remyophyton, being the gametophyte of Rhynia, is represented by a dense stand of in situ preserved gametophytes with antheridia- and archegonia-bearing axes. The gametophytes are remarkably small in comparison to those of other Rhynie chert plants. The generic diagnoses of Lyonophyton and Langiophyton are emended to include archegonia- and antheridiabearing axes. All essential stages of the reproductive cycle, i.e. sporophytes, and male and female gametophytes, can now be demonstrated for three of the six land plants from the Rhynie chert, i.e. Rhynia gwynne-vaughanii, Aglaophyton major and Horneophyton lignieri.

Evidence for an early terrestrial food web: coprolites from the Early Devonian Rhynie chert

Fossils in the Pragian Rhynie cherts, Aberdeenshire, Scotland, are preserved with exquisite cellular detail, and provide much information on Early Devonian terrestrial and freshwater ecosystems. The fossils include abundant and diverse coprolites which demonstrate the existence of consumers differing in life-habit and diet. The coprolites are small (0.5–3 mm) and diverse in morphology and content, including groups of amorphous coprolites as well as coprolites with identifiable, particulate content. The present authors define three new ichnogenera to accommodate these coprolites: • Lancifaex encompasses elongate coprolites with particulate content, and includes three ichnospecies, distinguished on morphology, L. simplex, L. divisa and L. moniliforma . • Rotundafaex encompasses rotund coprolites with particulate content, and includes a single ichnospecies, R. aggregata . • Bacillafaex encompasses rod-shaped coprolites with amorphous content, and includes two ichnospecies, distinguished on size, B. constipatus and B. mina . Typically, plant spores do not dominate the content of these coprolites, but the population does include some spore-rich coprolites. The presence of spore-rich coprolites in this diverse assemblage adds evidence to the debate on spore-feeding as a nutritional strategy in early terrestrial ecosystems. The authors conclude that the coprolites described here indicate at least four types of consumer including detritivores and herbivores. Spore-rich coprolites might suggest sporivory; however, comparison with the faeces of modern millipedes demonstrates that they might equally well be the product of detritivores. The continuum observed here between spore-rich and spore-poor coprolites implies that, in this assemblage, spore-rich coprolites do not constitute a distinct group. Rather, they are part of a group of elongate, ellipsoidal coprolites with heterogeneous content that includes, at one extreme, coprolites which lack plant spores, and at the other, coprolites which contain abundant plant spores. Most coprolites in this group fall somewhere between the two extr