Phyllolepid placoderm fish remains from the Devonian Aztec Siltstone, southern Victoria Land, Antarctica

2005 ◽  
Vol 17 (3) ◽  
pp. 387-408 ◽  
Author(s):  
GAVIN C. YOUNG ◽  
JOHN A. LONG

Phyllolepid placoderm remains from the Aztec Siltstone fish fauna are described as Austrophyllolepis quiltyi sp. nov., Austrophyllolepis cf. A. youngi, Placolepis tingeyi sp. nov., and phyllolepid indet. The new Antarctic species of two genera previously only known from Australia reinforce evidence from other fish taxa of close biogeographic affinity, as part of the eastern margin of Palaeozoic Gondwana. At least three genera and four species gives the Aztec Siltstone fish fauna the most diverse phyllolepid assemblage known, and probably the oldest documented so far (?late Middle Devonian). Specimens of Austrophyllolepis from the type locality at Mount Howitt, Victoria, are refigured for comparison with the Antarctic species. The order Phyllolepida is a key group for understanding Devonian vertebrate biogeography and palaeogeography, with a unique disjunct distribution in both time and space between the Southern and Northern hemispheres. Phyllolepids document one of the major dispersal events in early vertebrate history, which approximately coincided with the Frasnian–Famennian boundary mass extinction during the Late Devonian.

Fossil Record ◽  
2002 ◽  
Vol 5 (1) ◽  
pp. 155-206 ◽  
Author(s):  
G. C. Young ◽  
J. M. Moody

A new Devonian fossil fish fauna from the region of Caño Colorado between the Rio Palmar and Rio Socuy, Sierra de Perijá, Venezuela, comes from two localities and several horizons within the Campo Chico Formation, dated on plants and spores as Givetian-Frasnian in age. Placoderms are most common, with the antiarch <i>Bothriolepis perija</i> n. sp., showing affinity with species from the Aztec fish fauna of Victoria Land, Antarctica. A second antiarch, <i>Venezuelepis mingui</i> n.g. n.sp., is also closely related to an Antarctic species, which is reassigned to this new genus. Fragmentary remains of a phyllolepid placoderm show similarity to the genus <i>Austrophyllolepis</i> from southeastern Australia. Chondrichthyan spines are provisionally referred to the Antarctilamnidae, and acanthodian remains include spines of the widespread taxon <i>Machaeracanthus</i>. Osteichthyans are represented by osteolepid and dipnoan scales and teeth, and scales lacking cosmine which may belong to another major taxon. This fauna has provided the first Devonian record from South America of three major fish groups: antiarch and phyllolepid placoderms, and dipnoans. These are widely distributed on most other continents. Although invertebrates and plants from the same sequence closely resemble those of eastern North America, the endemic elements in the fish fauna indicate Gondwana affinities. Phyllolepid placoderms are common in Givetian-Frasnian strata of Australia and Antarctica, but are only known from the Famennian in the Northern Hemisphere. The new phyllolepid occurrence extends their range across the northern margin of Palaeozoic Gondwana. The age and affinities of this new fish fauna are consistent with a model of biotic dispersal between Gondwana and Euramerica at or near the Frasnian-Famennian boundary. A narrow marine barrier separating northern and southern continental landmasses is indicated, in contrast to the wide equatorial ocean for the Late Devonian postulated from palaeomagnetic data. <br><br> Es wird eine neue devonische Fischfauna aus dem Gebiet zwischen Caño Colorado und Rio Socuy, Sierra de Perijá, beschrieben. Die Funde stammen aus zwei Lokalitäten und mehreren Horizonten innerhalb der Campo Chico Formation, die auf Grundlage von Untersuchungen der Pflanzen- und Sporenfunde dem Zeitabschnitt Givetium-Frasnium zugeordnet werden. Placodermen sind durch den Antiarchen <i>Bothriolepis perija</i> n. sp. häufig vertreten. Sie sind mit Arten der Aztec-Fischfauna von Viktoria Land, Antarktis, verwandt. Ein zweiter Antiarche, der <i>Venezuelepis mingui</i> n. g. n. sp. ist eng mit einer Spezies aus der Antarktis verwandt, die ebenfalls dieser neuen Gattung zugeschrieben wird. Fragmentarische Reste eines phyllolepiden Placodermen weisen Ähnlichkeiten mit der Gattung <i>Austrophyllolepis</i> aus dem Südosten Australiens auf. Wirbel eines Chondrichthyer werden vorläufig den Antarctilamnidae zugeschrieben. Acanthodir-Reste schließen das weitverbreitete Taxon <i>Machaeracanthus</i> ein. Osteichthyer sind durch Schuppen und Zähne osteolepider Sarcopterygier und Dipnoi vertreten. Andere Schuppen, denen die Cosminschicht fehlt, gehören vermutlich zu einem anderen Haupttaxon. Damit ist durch diese Fauna der erste Nachweis für das Vorkommen der drei Hauptfischgruppen Antiarchi, phyllolepide Placodermi und Dipnoi im Devon Südamerikas erbracht. Sie sind auch auf den meisten anderen Kontinenten weit verbreitet. Obwohl Invertebraten und Pflanzen aus derselben Zeit sehr denen aus dem Osten Nordamerikas ähneln, weisen die endemischen Elemente in der Fischfauna auf eine Affinität zu Gondwana hin. Phyllolepide Placodermen sind im Givetium-Frasnianium Australiens verbreitet, aber erst aus dem Famennium in der Nordhemisphere bekannt. Das Auftreten eines neuen Phyllolepiden weitet den Vorkommensbereich über die nördliche Linie des paläozoischen Gondwanas hinaus aus. Alter und Verwandtschaftsbeziehungen dieser neuen Fischfauna stimmen mit dem Modell der biotischen Verbreitung zwischen Gondwana und Euramerika an bzw. nah an der Frasnium-Famennium-Grenze überein. Es gibt Hinweise für eine die nördlichen und südlichen Landmassen trennende schmale Meerenge. Dies steht im Gegensatz zur Annahme eines weiten äquatorialen Ozeans im späten Devons, die sich auf palaeomagnetische Daten stützt. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.20020050111" target="_blank">10.1002/mmng.20020050111</a>


2014 ◽  
Vol 62 (1) ◽  
pp. 44 ◽  
Author(s):  
Gavin C. Young ◽  
John A. Long

A small collection of arthrodire remains is described from the Devonian Aztec Siltstone of southern Victoria Land, Antarctica. Barwickosteus antarcticus, gen. et sp. nov., is a small phlyctaeniid arthrodire probably closely related to Barrydalaspis from the Bokkeveld Group of South Africa. Grifftaylor antarcticus, gen. et sp. nov., is a generalised phlyctaeniid resembling Phlyctaenius and Neophlyctaenius. New specimens of Boomeraspis show that it had a high-spired trunk-armour with a median dorsal plate of similar proportions to Tiaraspis, Mithakaspis, Turrisaspis or Africanaspis. Other fragmentary median dorsal plates are provisionally referred to Turrisaspis and Mulgaspis. With these new taxa the vertebrate assemblage from the Aztec Siltstone comprises at least 37 genera and 50 species, making it one of the most diverse of Middle–Late Devonian age.


2010 ◽  
Vol 22 (6) ◽  
pp. 805-814 ◽  
Author(s):  
Laura Ghigliotti ◽  
Thomas J. Near ◽  
Sara Ferrando ◽  
Marino Vacchi ◽  
Eva Pisano

AbstractAntarctic plunderfishes (Notothenioidei, Artedidraconidae) are important components of the Southern Ocean fish fauna. As a contribution to the Victoria Land Transect Project, we performed a cytogenetic analysis of six species from three of the four artedidraconid genera,Artedidraco glareobarbatus,A. orianae,A. skottsbergi,A. shackletoni,Histiodraco velifer, andPogonophrynesp. We investigated the species-specific cytogenetic features and highlighted patterns of chromosomal evolutionary change using a molecular phylogeny based on mitochondrial and nuclear genes. Despite a conserved diploid number, some important karyotypic traits account for major differences among artedidraconid species. Specific cytogenetic features, including the chromosomal organization of ribosomal genes and the occurrence of sex chromosomes, are characteristics ofA. skottsbergi, making this species distinct among those studied. These chromosomal peculiarities are consistent with the phylogenetic hypothesis resolvingA. skottsbergias the sister lineage of all other Artedidraconidae. A karyological similarity was found betweenA. glareobarbatusandA. shackletoniconsistent with their inferred sister species relationship in the phylogeny. The results indicate that artedidraconids are not conservative in their genomic organization at the chromosomal level and provide new evidence for the degree of biological diversity in this notothenioid group.


PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5636
Author(s):  
Jack Stack ◽  
Lauren Sallan

We surveyed the taxa, ecosystems, and localities of the Devonian fishes of Michigan to provide a framework for renewed study, to learn about the diversity and number of these fishes, and to investigate their connection to other North American faunas. Nineteen genera of fishes have been found in the Middle and Late Devonian deposits of Michigan, of which thirteen are ‘placoderms’ represented by material ranging from articulated head shields to ichthyoliths. As expected from the marine nature of these deposits, ‘placoderms’ are overwhelmingly arthrodire in nature, but two genera of ptyctodonts have been reported along with less common petalichthyid material. The remaining fish fauna consists of fin-spines attributed to ‘acanthodians’, two genera of potential crown chondrichthyans, an isolated dipnoan, and onychodont teeth/jaw material. There was an apparent drop in fish diversity and fossil abundance between Middle and Late Devonian sediments. This pattern may be attributed to a paucity of Late Devonian sites, along with a relative lack of recent collection efforts at existing outcrops. It may also be due to a shift towards open water pelagic environments at Late Devonian localities, as opposed to the nearshore reef fauna preserved in the more numerous Middle Devonian localities. The Middle Devonian vertebrate fauna in Michigan shows strong connections with same-age assemblages from Ohio and New York. Finally, we document the presence of partially articulated vertebrate remains associated with benthic invertebrates, an uncommon occurrence in Devonian strata outside of North America. We anticipate this new survey will guide future field work efforts in an undersampled yet highly accessible region that preserves an abundance of fishes from a critical interval in marine vertebrate evolution.


Diversity ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 506
Author(s):  
Claudia Brunetti ◽  
Henk Siepel ◽  
Peter Convey ◽  
Pietro Paolo Fanciulli ◽  
Francesco Nardi ◽  
...  

In the harsh Antarctic terrestrial ecosystems, invertebrates are currently confined to sparse and restricted ice free areas, where they have survived on multi-million-year timescales in refugia. The limited dispersal abilities of these invertebrate species, their specific habitat requirements, and the presence of geographical barriers can drastically reduce gene flow between populations, resulting in high genetic differentiation. On continental Antarctica, mites are one of the most diverse invertebrate groups. Recently, two new species of the free living prostigmatid mite genus Stereotydeus Berlese, 1901 were discovered, bringing the number of Antarctic and sub-Antarctic species of this genus up to 15, of which 7 occur along the coast of Victoria Land and in the Transantarctic Mountains. To examine the biodiversity of Stereotydeus spp., the present study combines phylogenetic, morphological and population genetic data of specimens collected from nine localities in Victoria Land. Genetically distinct intraspecific groups are spatially isolated in northern Victoria Land, while, for other species, the genetic haplogroups more often occur sympatrically in southern Victoria Land. We provide a new distribution map for the Stereotydeus species of Victoria Land, which will assist future decisions in matters of the protection and conservation of the unique Antarctic terrestrial fauna.


1913 ◽  
Vol 49 (2) ◽  
pp. 229-292 ◽  
Author(s):  
C. Tate Regan

Our knowledge of the Antarctic fish-fauna has greatly increased during the last ten years. The Belgian expedition to Graham Land (1897–1899) was followed by that of the Southern Cross to Victoria Land (1898–1900), fitted out by Sir George Newnes. Next were the British expedition of the Discovery to Victoria Land and Edward Land (1901–1904), the German voyage of the Gauss to Kerguelen and Willhelm Land (1901–1903), and Nordenskjöld's Swedish expedition to South Georgia, the South Shetlands, and Graham Land. Then came the voyage of the Scotia to the South Orkneys and Coats Land (1902–1904), and Charcot's expeditions to the Palmer Archipelago and Graham Land in the Français. (1904–1905) and the Pourquoi Pas? (1908–1910), and finally Shackleton's expedition (1908–1909).


1992 ◽  
Vol 4 (1) ◽  
pp. 89-105 ◽  
Author(s):  
S. Turner ◽  
G. C. Young

A new fossil agnathan, Turinia antarctica sp. nov., based on numerous isolated scales, comes from the lower fish-bearing beds of the Aztec Siltstone. Scales from moraine at Mount Suess, originally described as selachian or psammosteid heterostracan, are referred to the new species which shows close affinity with T. gondwana from Bolivia and T. cf. hutkensis from Iran. Reassessment of the biostratigraphy of Middle Devonian turiniid scales suggests that the lower part of the Aztec Siltstone may be of Eifelian age.


2009 ◽  
Vol 36 (1) ◽  
pp. 77-99 ◽  
Author(s):  
ANN DATTA

The bibliography brings together more than 250 scientific papers and books written by Alwyne (Wyn) Wheeler over fifty years, from 1955–2006. This chronological list shows that from the beginning his research followed three themes: taxonomy of historically important fish collections; identification and distribution of the British and European fish fauna ; the status of British fishes in a changing environment. Until the mid-point in Wyn's career he published regularly on the identification of fish remains in archaeological sites in Britain and Europe. Wyn also wrote under an alias, Allan Cooper, and these have been listed separately. The bibliography concludes with a selection of the regular columns he contributed to angling magazines.


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