- Detalles de la revista
- Publicado por primera vez
- 20 Nov 2014
- Periodo de publicación
- 1 tiempo por año
- Acceso abierto
The Cuticles of (?) Thylacocephalan Arthropod from the Basal Choteč Event (Choteč Formation, Eifelian; Barrandian Area, Czech Republic)
Páginas: 1 - 12
Small fragments of phosphatic cuticle have been observed in dark limestone of the early Eifelian age (Choteč Formation) in the interval of the Basal Choteč Event. The cuticle is two-layered, primarily folded, with a chamber between outer and inner walls. Fragments likely represent small cuticle pieces from the margins of the carapace. The exterior of the cuticle is nearly smooth bearing irregular network of wrinkled polygons or shallow pits. Low conical mound-like to high thorn-like spines with annular structure extend from both outer and inner surface of cuticle. Wrinkled and folded bases of these spines indicate moderate flexibility of cuticle. Spines are hollow, the higher ones often with apical opening. The inner surface of carapace carries smaller spines or is nearly smooth. Chamber walls inside the cara-pace are with folds and other structures supporting stiffness of the cuticle. The internal walls of the cuticle are covered by polygonal bumps. These uniformly sized and shaped bumps are about 1 μm sized and likely represents imprints of the epithelial cells adjoined to the basal membranous layer of endocuticle.
Biological affinity of cuticle fragments is unclear. They surely represent pieces of the arthropod cara-pace, the most probably a thylacocephalan. Associated fossils indicate a deeper marine environment. Bloom of prasinophytes, abundance of dacryoconarids and organophosphatic brachiopods, and striking rarity and diminutive size of other fauna indicate eutrophic conditions in a neritic sea, likely with hypoxic bottom water. Nectonic mode of life in open sea can be suggested for an animal bearing this cuticle.
- epithelian moulds
- Acceso abierto
Reproductive Biology of the Arborescent Seed-Fern
Linopteris obliqua: Implications for Taxonomy (Medullosales, Late Pennsylvanian Sydney Coalfield, Canada)
Páginas: 13 - 21
A shaley slab (65 x 45 x 7 cm) from the Sydney Coalfield, Canada, Cantabrian age, on splitting apart revealed 2 – 3 layers each entombing thousands of abscised pinnules of Linopteris obliqua and eight dispersed compound-synangial structures. The campanulary-ventral-sporal micromorphology of the best preserved structure of these compares sufficiently well with previously reported structures from the Sydney Coalfield named Potoniea krisiae. Earlier studies involving larger sampling suites furthermore contributed to the observation that Hexagonocarpus sp. (female organ) and P. krisiae (male organ) usually co-occur with abscised L. obliqua pinnules; however, these two organs do not co-occur on isochronous bedding planes. In the absence of confirmatory organic attachments, the presented data provide as yet the strongest support for the hypothesis of the organs’ connectivity, but whether female-male trees existed or not, and the mode of attachment of the organs remain unknown. Hypothesized for the latter is pinnate attachment.
- Potoniea krisiae
- Acceso abierto
Specialized Adhesive Pad of a Climbing Pteridosperm from Permian Peat-Forming Forest (Wuda, Inner Mongolia)
Páginas: 23 - 28
Certain pteridosperm tendril adhesive pads are depicted from the Cathaysian flora of the Early Permian Taiyuan Formation of Wuda Coal-field in Inner Mongolia China. Specimens contain elliptical or rounded pads situating at the swollen tip of pinnule lobe tendrils which are highly comparable to those of the extant Parthenocissus tricuspidata in the way that both of them are similar in form and function. Specifically, information we have gained suggested that pteridosperms from the Permian might have performed a similar type of physiological process by producing some chemical substances which assisted them in climbing. The Wuda pteridosperm likely to climbed on Cordaites or Sigillaria trees. Moreover, physical principles such as the pressure difference between inside and outside of the pads also seems to play an important role in assisting climbing. The new finding indicates that some pteridosperms in the Permian Cathaysian flora possessed climbing growth habit as well as those in the Late Carboniferous Euramerica Flora, where climbing/scrambling growth habit is well known in the coal swamp forests. This finding shows one of the several earliest climbing habits in Cathaysia Flora and thus remarkably promotes our understanding of the growth habit of pteridosperm and the change in plant community structure in that area.
- sucker-like structure