Topic
Dipterus
About: Dipterus is a research topic. Over the lifetime, 24 publications have been published within this topic receiving 369 citations.
Papers
TL;DR: The axial skeleton and fin supports of the Middle Devonian lungfish Dipterus are described from a range of specimens from the Orcadian Basin of Scotland as discussed by the authors, and they offer support for a lungfish-porolepiform sistergroup relationship.
Abstract: The axial skeleton and fin supports of the Middle Devonian lungfish Dipterus are described from a range of specimens from the Orcadian Basin of Scotland. The axial skeleton of the trunk region consists of intercentra, relatively short ribs, and neural arches bearing two rows of supraneural spines; posteriorly, the intercentra are replaced by haemal arches. The notochord seems to have been essentially unconstricted. There may have been two pairs of cranial ribs. In general terms the vertebral column resembles that of Neoceratodus but is more fully ossified. The only known paired fin support of Dipterus is an archipterygial structure resembling those of Neoceratodus, with at least seven mesomeres and jointed pre- and postaxial radials. The pectoral fin is rotated as in modern lungfishes. The median fin supports all consist of basal plates supporting radials. In the posterior dorsal fin support the posterior radials form a branched structure. The heterocercal tail is supported by segmental radials. A new body reconstruction is presented.The characters possessed by Dipterus offer support for a lungfish–porolepiform sistergroup relationship. All known lungfishes fit into a single cumulative series of postcranial morphologies. The evidence for a paedomorphic trend in lungfish phylogeny is interesting but inconclusive.
42 citations
TL;DR: Pore canal systems of fossil lungfishes are regarded as evidence of a complex cutaneous vasculature involved in the deposition of mineralized tissues, including the theory that electroreceptors played an important part in the origin of the dermal skeleton.
Abstract: Improved structural and functional interpretations regarding the dermal skeleton of Paleozoic lungfishes (Dipnoi) can be derived from a direct comparison of Recent and fossil tissues. In particular, skin from the snout of adult Australian lungfish (Neoceratodus forsteri) contains horizontal plexuses and vertical capillary loops which resemble in structure, size and density components of the cosmine layer in such Paleozoic lungfishes as Dipterus valenciennesi and Chirodipterus australis. In addition to these dermal papillae, the skin of the snout also contains ampullary electroreceptors, goblet cells, compound mucus glands, and terminal branches and openings of the mechanoreceptive lateral line system. Pore canal systems of fossil lungfishes previously have been interpreted as housing electroreceptors or other cutaneous sense organs of the lateral line system. In contrast, we regard pore canal systems as evidence of a complex cutaneous vasculature involved in the deposition of mineralized tissues. Prevailing ideas on the structure and biological role of cosmine are reinterpreted, including the theory that electroreceptors played an important part in the origin of the dermal skeleton.
37 citations
TL;DR: It is shown that Palaeospondylus is the larval stage of a lungfish, most probably Dipterus valenciennesi Sedgwick and Murchison 1828 (ref. 5), and that development of the adult form requires a distinct metamorphosis.
Abstract: Perhaps the most enduring of puzzles in palaeontology has been the identity of Palaeospondylus gunni Traquair, a tiny (5-60-mm) vertebrate fossil from the Middle Devonian period (approximately 385 Myr ago) of Scotland, first discovered in 1890 (refs 1-3). It is known principally from a single site (Achanarras Quarry, Caithness) where, paradoxically, it is extremely abundant, preserved in varved lacustrine deposits along with 13 other genera of fishes. Here we show that Palaeospondylus is the larval stage of a lungfish, most probably Dipterus valenciennesi Sedgwick and Murchison 1828 (ref. 5), and that development of the adult form requires a distinct metamorphosis. Palaeospondylus is the oldest known true larva of a vertebrate.
36 citations
TL;DR: Sorbitorhynchus deleaskitus as discussed by the authors is the only Early Devonian dipnoan for which the full hyoid arch, gular, basibranchial, and submandibular plates are preserved, and in which the parasphenoid is clearly defined.
Abstract: A dipnoan species from the Emsian of Guangxi, China, Sorbitorhynchus deleaskitus , which has previously been diagnosed in the appendix to a more general paper on dipnoan phylogeny (Cambell & Barwick 1990), is described in detail. The head is large and heavily ossified, with cosmine on the external dermal bones. The dental plates are thick and have few poorly defined large tuberosities towards their anterolateral edges. It is the only Early Devonian dipnoan for which the full hyoid arch, gular, basibranchial, and submandibular plates are preserved, and in which the parasphenoid is clearly defined. In many features the genus is more advanced than Dipnorhynchus , but in none is it more advanced than Dipterus , apart from the loss of the buccohypophysial foramen. It gives a new perspective on late Emsian evolution of the group, and reinforces our concept of an independently developing dentine-plated line contemporaneous with a true tooth-plated line.
36 citations
TL;DR: The structure and significance of a new dipnoan genus and species, Tarachomylax oepiki, from the Emsian of Severnaya Zemlya (Siberian Arctic) is discussed in this article.
36 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2018 | 1 |
| 2015 | 1 |
| 2014 | 1 |
| 2010 | 1 |
| 2009 | 2 |
| 2008 | 1 |