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Complete Specimen (complete + specimen)

Distribution by Scientific Domains
Earth and Environmental Science60%

Selected Abstracts

On the phylogenetic position of Gogonasus andrewsae Long 1985, within the Tetrapodomorpha

ACTA ZOOLOGICA, Issue 2009
Timothy Holland
Abstract Within the Tetrapodomorpha, the Late Devonian Gogonasus andrewsae of the Gogo Formation, Gogo, Western Australia, has occupied an uncertain phylogenetic position. Following the description of several well-preserved three-dimensional skulls and pectoral girdles, the discovery of the first complete specimen (NMV P221807) made Gogonasus one of the best-known tetrapodomorph fish. Recent studies of pectoral fin structure and the spiracular opening of Gogonasus have suggested an unexpected affinity with ,elpistostegalid' fish such as Tiktaalik. Subsequent work has refuted characters linking these taxa, with phylogenetic analysis of the Tetrapodomorpha placing Gogonasus basal to megalichthyids and tristichopterids. In this paper we reanalyse characters linking Gogonasus with ,elpistostegalid' fish and those supporting the placement of Gogonasus crownward of Eusthenopteron. New phylogenetic analyses of the Tetrapodomorpha show a revised phylogenetic position of Gogonasus as being deeply nested within the Tetrapodomorpha, crownward of Osteolepis and Megalichthys, but basal to Eusthenopteron+,elpistostegalids'. Functional consideration of the spiracular structure suggests a position of Gogonasus closer to ,elpistostegalids', although data is lacking from other less-well-preserved taxa to fully test the hypothesis. The humerus of the Late Devonian lungfish Chirodipterus from Gogo, Western Australia is figured for comparative purposes. [source]

A New Jawless Vertebrate from the Middle Devonian of Scotland

PALAEONTOLOGY, Issue 1 2001
M. J. Newman
A new jawless vertebrate, Cornovichthys blaauweni gen. et sp. nov., is described from a single complete specimen from the Achanarras fish bed at Achanarras Quarry in Caithness, northern Scotland. The Achanarras fish bed consists of lacustrine laminites and was deposited in a major deep-water phase of the Orcadian lake during the deposition of the cyclic Caithness Flagstone Group. The Achanarras fish bed is of Middle Devonian (Eifelian) age. The new animal compares closely with Euphanerops, one ofthe Frasnian ,anaspids' (Hyperoartii) of the Escuminac Formation at Miguasha, Quebec, Canada. [source]

A New Symmetrodont Mammal with Fur Impressions from the Mesozoic of China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2003
Guillermo W. ROUGIER
Abstract, Western Liaoning of northeastern China is world-renowned for the Mesozoic Jehol biota, especially for yielding many feathered dinosaurs, primitive birds, mammals and fossil angiosperm. This paper describes a complete specimen of a symmetrodont mammal with well-preserved hairs and soft tissue from the basal part of the Yixian Formation in the Sihetun area, Beipiao, western Liaoning. It is significant for understanding the morphology, osteology, phylogeny and life habits of Mesozoic symmetrodont mammals. [source]

Morpho-anatomy of the lobopod Magadictyon cf. haikouensis from the Early Cambrian Chengjiang Lagerstätte, South China

ACTA ZOOLOGICA, Issue 4 2007
Jianni Liu
Abstract Magadictyon haikouensis (Luo and Hu, 1999) from the Early Cambrian Chengjiang Lagerstätte, an incomplete specimen of a large lobopod with strong appendages, has been regarded as related to the lobopods Microdictyon and Onychodictyon. Newly discovered complete specimens of Magadictyon cf. haikouensis (found by the Early Life Institute field team) show that the taxon, in addition to its strong appendages with appendicules, also had a head bearing similar caecum-like structures to those of the arthropod Naraoia and Chelicerate, ,Peytoia'-like mouthparts and frontal appendages. Because of their similarity, the caecum-like structures of Magadictyon cf. haikouensis are considered to be homologous with those of stem-group arthropods. The ,Peytoia'-like mouthparts and the frontal appendages are similar to those of the AOPK (Anomalocaris,Opabinia,Pambdelurion,Kerygmachela) group. In addition, the appendages with appendicules show that Magadictyon cf. haikouensis is closely related to Onychodictyon. Therefore, Magadictyon cf. haikouensis is regarded here as a rare transitional form between lobopods and arthropods. Besides, together with other lobopods, the morphology of Magadictyon cf. haikouensis demonstrates that the Cambrian lobopods appear to have been diverse and not particularly closely related to one another, and do not seem to represent a monophyletic clade. [source]

A New Perleidiform (Actinopterygii, Osteichthyes) from the Middle Anisian (Middle Triassic) of Yunnan, South China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2009
Zuoyu SUN
Abstract: Two complete specimens from the Pelsonian (Middle Anisian, Middle Triassic) of Luoping, Yunnan Province, South China are referred to a new actinopterygian genus, Luopingichthys gen. nov., and ascribed to the perleidiform family Polzbergidae based especially on a typical synapomorphy of a peculiar premaxillary-maxillary complex, i.e., the fusion between premaxillary and maxillary along the antero-dorsal margin of the maxillary. The new taxon differs from other deep-bodied representatives of the family, Felberia and Stoppania, in its fusiform or deep fusiform body shape; sickle-shaped preopercular with short infraorbital process; lack of modified scales at the base of the anal fin; the short-based dorsal fin; scarcely ornamented scales; and thin anterior teeth. Based on a redescription of the holotype of the taxon Ctenognathichthys hattichi from the Middle Triassic (Ladinian) Prosanto Formation, Canton Graubünden, eastern Switzerland, the only known specimen, which shows the same fusion between premaxillary and maxillary, the systematic position of the species is clarified and the taxon is proposed to be a further representative of the family Polzbergidae, and is transferred to the new genus. [source]