Algae from the Rhynie Chert

New material collected from the Rhynie Chert Bed (Siegenian age) has revealed new filamentous and unicellular algae. Two of the filamentous forms and one palmelloid form are described. Filamentous and unicellular algae are particularly common in a white kind of chert not previously reported and which is interpreted as having been formed by the in situ silicification of a silicate-rich pond.
Some rhizoid-nodes of Palaeonitella cranii (Kidston & Lang) Pia and a possible rhizoid-borne pro-embryo are also described and compared with similar structures in living Charophyta.     

Testate Amoebae in the 407-Million-Year-Old Rhynie Chert

1. Download high-res image (117KB)
2. Download full-size image

     

Aglaophyton major, a non-vascular land-plant from the Devonian Rhynie Chert

EDWARDS, D. S., 1986. Aglaophyton major , a non-vascular land-plant from the Devonian Rhynie Chert. The genus Aglaophyton is described to accommodate the plant formerly known as Rhynia major , re-examined using new material and techniques. The plant, which is a sporophyte, is suggested to have been shorter than originally supposed and to have formed extensive stands of decumbent axes. These features, with information on the angle of dichotomous branching and the frequency of sporangia, are incorporated into a new reconstruction of the plant. The conducting strand within the axes consists of three zones, a central region of thin-walled cells, a middle region of thick-walled cells and an outer region of thin-walled cells. There is no indication of differential wall thickenings in the cells of any of these zones and the strand is interpreted in terms of a bryophytic conducting strand, the inner two regions being comparable to hydroids and the outer region comparable to the leptoids found in polytrichaceous moss gametophytes and sporophyles. The plant thus exhibits characters intermediate between tracheophytes and some mosses and cannot be considered a member of either group; at the present time it is not assigned to a higher category. A rediagnosis of Rhynia gwynne-vaughanii , based on published results and new data, is also included.     

Palaeontology: the 165-million-year itch

New flea-like fossils from China provide a rare, tantalizing glimpse of bizarre insects in the Cretaceous and Jurassic. Possibly the oldest flea-like animals known, they provide a challenge to the functional morphologist to infer which animals they may have targeted.     

Fungi from the Lower Devonian Rhynie chert: My Coparasitism

Several examples of mycoparasitism are described from the Lower Devonian (Siegenian) Rhynie chert. These fungal interactions include thick-walled chlamydospores and vesicles in which epibiotic fungi are attached to the outer surface of the spore. Other fossil spores are characterized by mycoparasites developing between the layers of the spore wall or within the lumen. The presence of callosities extending from the inner surface of some fossil spores demonstrates that the hosts were alive when parasitized. This response by the mycohost is identical to that found in certain modem mycoparasitic symbioses involving vesicular arbuscular mycorrhizae that are parasitized by various aquatic fungi. The presence of mycoparasitism in a 400-million-year-old ecosystem underscores the potential significance of the fungal genome early in the evolution of other organisms.     

Fungal colonization of the rooting system of the early land plant Asteroxylon mackiei from the 407‐Myr‐old Rhynie Chert (Scotland,UK)

Associations between plants and fungi were an important and varied feature of early terrestrial ecosystems, but in most instances their biological functions remain poorly understood. We document a new species of fungus colonizing the rooting system of the early lycopod Asteroxylon mackiei, based on exceptionally well‐preserved fossils from the Rhynie Chert. We investigated historical petrographic thin sections using standard optical microscopy and confocal laser scanning microscopy. P alaeozoosporites renaultii gen. nov., sp. nov. colonized the inner cortex of the plant rooting system. The fungus had an aseptate thallus with isotomous or sympodial branching. The mycelium bore distinctive porate, globose to elongated structures that we interpret as zoosporangia and resting sporangia. Doubts remain over the precise systematic affinity of P. renaultii, which closely resembles chytrids. Whereas most of the Rhynie Chert plants developed symbiotic associations of the mycorrhizal type, it seems that this was not the case for Asteroxylon mackiei, which possessed the most evolved rooting system among the Rhynie Chert plants. We argue that the new root‐borne fungus was probably parasitic. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 201–213.     

Giving Is Nicer than Taking: Preschoolers Reciprocate Based on the Social Intentions of the Distributor

Recent research has found that even preschoolers give more resources to others who have previously given resources to them, but the psychological bases of this reciprocity are unknown. In our study, a puppet distributed resources between herself and a child by taking some from a pile in front of the child or else by giving some from a pile in front of herself. Although the resulting distributions were identical, three- and five-year-olds reciprocated less generously when the puppet had taken rather than given resources. This suggests that children’s judgments about resource distribution are more about the social intentions of the distributor and the social framing of the distributional act than about the amount of resources obtained. In order to rule out that the differences in the children’s reciprocal behavior were merely due to experiencing gains and losses, we conducted a follow-up study. Here, three- and-five year olds won or lost resources in a lottery draw and could then freely give or take resources to/from a puppet, respectively. In this study, they did not respond differently after winning vs. losing resources.     

Anthony's Feast: The Gift in Abelam Aesthetics

In this essay I take up a major theme in the work of Anthony Forge: the relationship between word and image. Focusing on the problem of what the Abelam say (or do not say) about the design elements in masculine initiation rites, I explore the relationship between language and the exchange relations that are involved in the ceremony. While the Abelam have no explicit way of explaining the design elements, initiation involves a constructed and aestheticised use of language. This lecture will investigate the word/image nexus from this viewpoint.     

The Estuary's Gift: An Atlantic Coast Cultural Biography

The Estuary's Gift: An Atlantic Coast Cultural Biography. David Griffith. University Park: Pennsylvania State University Press, 1999. 196 pp.     

Palaeontology in a molecular world: the search for authentic ancient DNA

The survival of ancient DNA in specimens up to several thousands of years old is established. However, there have been several claims concerning the recovery of geologically ancient DNA from fossil material many millions of years old. The authenticity of these fossil DNA sequences is questionable on theoretical and empirical grounds, and the existence of authentic geologically ancient DNA remains to be proven.     

Deciphering interfungal relationships in the 410-million-yr-old Rhynie chert: Morphology and development of vesicle-colonizing microfungi

The intraradical portion of arbuscular mycorrhizal (AM) fungi comprises mycelium, vesicles, and special physiological interfaces termed arbuscules; sometimes mycorrhizal fungi also produce spores within their hosts. Arbuscules are ephemeral structures that collapse after a few days, while the hyphae and vesicles appear to remain intact for some time after arbuscule senescence (post-arbuscule stage). However, little is known about the fate of mycorrhizal fungi in the post-arbuscule state. The Lower Devonian Rhynie chert yields the oldest fossil evidence of arbuscular mycorrhizas, including multiple specimens of mycorrhizal axes in the post-arbuscule stage. These fossils indicate that many older vesicles of Rhynie chert mycorrhizal fungi are colonized by other microfungi. Three types of fungal remains in vesicles are distinguished based on morphology and development: (1) spheroidal propagules up to 55 μm in diameter extending from short, distal branches of a hypha; (2) spheroidal propagules up to 23 μm in diameter produced within a tenuous mycelium; and (3) thin-walled propagules up to 10 μm in diameter within a hyphal inflation. The abundance of microfungal propagules in vesicles of Rhynie chert mycorrhizal fungi suggests that the mycorrhizal vesicles in some way positively affected the development and reproduction of the intrusive microfungi. Although the systematic affinities of the intrusive microfungi remain unresolved, this discovery is important because it broadens our understanding of the levels of organismal interactions that existed in early non-marine ecosystems.