A new basal actinopterygian fish from the Middle Devonian Aztec Siltstone of Antarctica

2008 ◽  
Vol 20 (4) ◽  
pp. 393-412 ◽  
Author(s):  
John A. Long ◽  
Brian Choo ◽  
Gavin C. Young
Keyword(s):  
Phylogenetic Analysis ◽  
Western Australia ◽  
Middle Devonian ◽  
Sister Taxon ◽  
Body Form ◽  
Victoria Land

AbstractA new basal actinopterygian fish, Donnrosenia schaefferi gen. et sp. nov., is described from the Middle Devonian (Givetian) Aztec Siltstone of southern Victoria Land, Antarctica. Donnrosenia gen. nov. is characterized by the large parietals which are of almost equivalent size to the frontals, very small intertemporals, a small accessory operculum situated dorsally to the prominent anterodorsal process of the suboperculum, a deep dentary with anterior flexure, porous ornamentation on the clavicle, an elongate body form with macromeric squamation, an absence of paired fringing fulcra on the fins, and pectoral lepidotrichia which are unsegmented for much of their length. A phylogenetic analysis based on dermal skeletal features of Devonian actinopterygians indicates that Donnrosenia gen. nov. is the sister taxon to Howqualepis from the Middle Devonian of Victoria, Australia, and is embedded within a possible clade containing the actinopterygians from the Gogo Formation, Western Australia. This supports the concept of an endemic radiation of East Gondwanan actinopterygians, and reinforces the already strong biogeographical similarities between the Middle Devonian palaeofaunas of Australia and Antarctica.

scholarly journals Evolutionary significance of the blastozoan Eumorphocystis and its pseudo-arms

2020 ◽  
pp. 1-17
Author(s):  
Thomas E. Guensburg ◽  
James Sprinkle ◽  
Rich Mooi ◽  
Bertrand Lefebvre
Keyword(s):  
Phylogenetic Analysis ◽  
Sister Taxon ◽  
Evolutionary Significance ◽  
Coelomic Cavity ◽  
Anatomical Features ◽  
New Findings ◽  
Solid Block ◽  
Cover Plates

Abstract Twelve specimens of Eumorphocystis Branson and Peck, 1940 provide the basis for new findings and a more informed assessment of whether this blastozoan (a group including eocrinoids, blastoids, diploporites, rhombiferans) constitutes the sister taxon to crinoids, as has been recently proposed. Both Eumorphocystis and earliest-known crinoid feeding appendages express longitudinal canals, a demonstrable trait exclusive to these taxa. However, the specimen series studied here shows that Eumorphocystis canals constrict proximally and travel within ambulacrals above the thecal cavity. This relationship is congruent with a documented blastozoan pattern but very unlike earliest crinoid topology. Earliest crinoid arm cavities lie fully beneath floor plates; these expand and merge directly with the main thecal coelomic cavity at thecal shoulders. Other associated anatomical features echo this contrasting comparison. Feeding appendages of Eumorphocystis lack two-tiered cover plates, podial basins/pores, and lateral arm plating, all features of earliest crinoid ‘true arms.’ Eumorphocystis feeding appendages are buttressed by solid block-like plates added during ontogeny at a generative zone below floor plates, a pattern with no known parallel among crinoids. Eumorphocystis feeding appendages express brachioles, erect extensions of floor plates, also unknown among crinoids. These several distinctions point to nonhomology of most feeding appendage anatomy, including longitudinal canals, removing Eumorphocystis and other blastozoans from exclusive relationship with crinoids. Eumorphocystis further differs from crinoids in that thecal plates express diplopores, respiratory structures not present among crinoids, but ubiquitous among certain groups of blastozoans. Phylogenetic analysis places Eumorphocystis as a crownward blastozoan, far removed from crinoids.

scholarly journals A new iguanodontian (Dinosauria: Ornithopoda) from the Early Cretaceous of Mongolia

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5300
Author(s):  
Terry A. Gates ◽  
Khishigjav Tsogtbaatar ◽  
Lindsay E. Zanno ◽  
Tsogtbaatar Chinzorig ◽  
Mahito Watabe
Keyword(s):  
Phylogenetic Analysis ◽  
Growth Stage ◽  
Phylogenetic Analyses ◽  
Type Specimen ◽  
Sister Taxon ◽  
New Taxon ◽  
Time Of Death ◽  
The North ◽  
Unusual Combination ◽  
Relationship Of

We describe a new iguanodontian ornithopod,Choyrodon barsboldigen. et sp. nov. from the Albian-aged Khuren Dukh Formation of Mongolia based on several partial skeletons interpreted to represent a subadult growth stage based on osteohistological features. This new taxon is diagnosed by many autapomorphies of the maxilla, nasal, lacrimal, opisthotic, predentary, and surangular.Choyrodondisplays an unusual combination of traits, possessing an open antorbital fenestra (a primitive ornithopod trait) together with derived features such as a downturned dentary and enlarged narial fenestra. Histological imaging suggests that the type specimen ofChoyrodonwould have been a subadult at the time of death. Phylogenetic analysis of two different character matrices do not positChoyrodonto be the sister taxon or to be more primitive than the iguanodontianAltirhinus kurzanovi, which is found in the same formation. The only resolved relationship of this new taxon is that it was hypothesized to be a sister-taxon with the North American speciesEolambia caroljonesa. Though discovered in the same formation andChoyrodonbeing smaller-bodied thanAltirhinus, it does not appear that the former species is an ontogimorph of the latter. Differences in morphology and results of the phylogenetic analyses support their distinction although more specimens of both species will allow better refinement of their uniqueness.

Reappraisal of arctostylopid mammal Kazachostylops occidentalis from the late Paleocene of Kazakhstan and phylogenetic relationships within Arctostylopida

2019 ◽  
Vol 94 (3) ◽  
pp. 568-579
Author(s):  
Alexander O. Averianov
Keyword(s):  
Phylogenetic Analysis ◽  
North American ◽  
Phylogenetic Relationships ◽  
New Genus ◽  
Principal Component ◽  
Sister Taxon ◽  
Phylogenetic Hypothesis ◽  
Lower Eocene ◽  
Principal Component Analyses ◽  
Upper Paleocene

AbstractKazachostylops occidentalis Nesov, 1987b, based on partial maxilla and dentary from the upper Paleocene Zhylga locality in South Kazakhstan, is redescribed. A new phylogenetic hypothesis of Arctostylopida is proposed based on phylogenetic analysis of 26 characters and 17 taxa. Kazachostylops is recovered as a sister taxon to the Arctostylopinae, the advanced clade of Asian and North American arctostylopids characterized by pseudohypocone on upper molars and reduced trigonid of lower molars, with the ectolophid being attached labial on the trigonid. Kazachostylops differs from more basal arctostylopids (Asiostylops, Allostylops, Bothriostylops, and Wanostylops) by higher-crowned molars, M1–3 metaconule absent, m1–3 entoconid connected with ectolophid by entolophid, and m2 wider than m1 and m3. Principal component analyses of the upper and lower dentition of arctostylopids show great distinctness of Kazachostylops from other members of the group. The arctostylopid taxa are reviewed, and the new genus Enantiostylops is erected for ‘Sinostylops’ progressus Tang and Yan, 1976 from the lower Eocene of China, because of uniquely concave parastylar area on upper molars.UUID: http://zoobank.org/a46d8f29-fd73-4e59-88dc-fcc55b12d1d3

scholarly journals Ferrodraco lentoni gen. et sp. nov., a new ornithocheirid pterosaur from the Winton Formation (Cenomanian–lower Turonian) of Queensland, Australia

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Adele H. Pentland ◽  
Stephen F. Poropat ◽  
Travis R. Tischler ◽  
Trish Sloan ◽  
Robert A. Elliott ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
New Genus ◽  
Sister Taxon ◽  
New Genus And Species ◽  
The Third ◽  
Mandibular Tooth

Abstract The Australian pterosaur record is poor by world standards, comprising fewer than 20 fragmentary specimens. Herein, we describe the new genus and species Ferrodraco lentoni gen. et sp. nov., based on the most complete pterosaur specimen ever found in Australia, and the first reported from the Winton Formation (Cenomanian–lower Turonian). The presence of premaxillary and mandibular crests, and spike-shaped teeth with subcircular bases, enable Ferrodraco to be referred to Anhangueria. Ferrodraco can be distinguished from all other anhanguerian pterosaurs based on two dental characters: the first premaxillary and mandibular tooth pairs are small; and the fourth–seventh tooth pairs are smaller than the third and eighth ones. Ferrodraco was included in a phylogenetic analysis of Pterosauria and resolved as the sister taxon to Mythunga camara (upper Albian Toolebuc Formation, Australia), with that clade occupying the most derived position within Ornithocheiridae. Ornithocheirus simus (Albian Cambridge Greensand, England), Coloborhynchus clavirostris (Valanginian Hastings Sands, England), and Tropeognathus mesembrinus (upper Aptian–lower Albian Romualdo Formation, Brazil) were resolved as successive sister taxa, which suggests that ornithocheirids were cosmopolitan during the Albian–Cenomanian. Furthermore, the stratigraphic age of Ferrodraco lentoni (Cenomanian–lower Turonian) implies that anhanguerians might have survived later in Australia than elsewhere.

Revision of the status of Saurolophus (Hadrosauridae) from California, USA

2010 ◽  
Vol 47 (11) ◽  
pp. 1417-1426 ◽  
Author(s):  
Phil R. Bell ◽  
David C. Evans
Keyword(s):  
Phylogenetic Analysis ◽  
Sierra Nevada ◽  
Sister Taxon ◽  
Morphological Evidence ◽  
Magmatic Arc ◽  
The Status ◽  
Previous Assignment ◽  
Geographic Setting

The occurrence of Saurolophus from the Moreno Formation (late Maastrichtian) of California is investigated and an incomplete, poorly preserved, skull (LACM/CIT 2852) is described. The skull lacks the braincase (including the frontals) and much of the nasals, and the preserved portions are crushed or plastically deformed, which makes anatomical interpretations difficult. A preserved midline fragment of the conjoined nasals suggests that it lacked a gryposaur-like “Roman nose”, but the nature of the crest, if present, is impossible to determine with certainty. A phylogenetic analysis places this specimen as either the sister taxon of Saurolophus or as the sister taxon to a clade comprising Edmontosaurus and Anatotitan . There is no compelling morphological evidence to support the previous assignment of LACM/CIT 2852 to Saurolophus rather than to Edmontosaurus, and its poor preservation prevents positive assignment to any taxon below Hadrosaurinae indet. Given its geographic setting and morphological uncertainties, it is also possible that this specimen represents a separate taxon, but more material is needed to clarify the identity of the Moreno hadrosaurine. LACM/CIT 2852 does, however, provide evidence that Maastrichtian hadrosaurines ranged west of the Sierra Nevada magmatic arc, in an area where dinosaur diversity is poorly known.

Description of a new specimen of Ianthasaurus hardestiorum (Eupelycosauria: Edaphosauridae) and a re-evaluation of edaphosaurid phylogeny

2010 ◽  
Vol 47 (6) ◽  
pp. 901-912 ◽  
Author(s):  
David M. Mazierski ◽  
Robert R. Reisz
Keyword(s):  
Phylogenetic Analysis ◽  
Fossil Record ◽  
Sister Taxon ◽  
Marginal Tooth ◽  
Tooth Morphology ◽  
Adult Individual ◽  
Full Resolution ◽  
Skeletal Material

Ianthasaurus hardestiorum , a basal edaphosaurid from the Upper Pennsylvanian of Garnett, Kansas, has been described on the basis of two incomplete, juvenile specimens and a series of disarticulated vertebral elements. New skeletal material of this poorly known species includes previously unknown cranial elements, increasing our knowledge of the anatomy and variation in this taxon. The complete ossification of the neural arches and the overall larger size of the vertebrae relative to those previously described indicate that they were part of an adult individual, and marginal tooth morphology resembles more closely that seen in the genus Edaphosaurus . Phylogenetic analysis of edaphosaurid synapsids confirms the hypothesis that Ianthasaurus is a sister-taxon of all other members of the clade. However, the incomplete fossil record of other putative edaphosaurids, such as Lupeosaurus and Glaucosaurus , makes full resolution of their phylogenetic interrelationships difficult to assess.

New arthrodires (placoderm fishes) from the Aztec Siltstone (late Middle Devonian) of southern Victoria Land, Antarctica

2014 ◽  
Vol 62 (1) ◽  
pp. 44 ◽  
Author(s):  
Gavin C. Young ◽  
John A. Long
Keyword(s):  
South Africa ◽  
New Taxa ◽  
Middle Devonian ◽  
Late Devonian ◽  
Dorsal Plate ◽  
Victoria Land ◽  
Small Collection ◽  
Vertebrate Assemblage ◽  
Devonian Age

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.

Biodiversity, distribution and patterns of extinction of the last odontopleuroid trilobites during the Devonian (Givetian, Frasnian)

2007 ◽  
Vol 144 (5) ◽  
pp. 777-796 ◽  
Author(s):  
RAIMUND FEIST ◽  
KENNETH J. McNAMARA
Keyword(s):  
Functional Analysis ◽  
New Species ◽  
New Taxa ◽  
Western Australia ◽  
Middle Devonian ◽  
Two New Species ◽  
New Material ◽  
Montagne Noire ◽  
Shell Bed

Biostratigraphical ranges and palaeogeographical distribution of mid-Givetian to end-Frasnian odontopleurids are investigated. The discovery of Leonaspis rhenohercynica sp. nov. in mid-Givetian strata extends this genus unexpectedly up to the late Middle Devonian. New material of Radiaspis radiata (Goldfuss, 1843) and the first koneprusiine in Britain, Koneprusia? sp., are described from the famous Lummaton shell-bed, Torquay, Devon. New taxa of Koneprusia, K. serrensis, K. aboussalamae, K. brevispina, and K. sp. A and K. sp. B are defined. Ceratocephala (Leonaspis) harborti Richter & Richter, 1926, is revised and reassigned to Gondwanaspis Feist, 2002. Two new species of Gondwanaspis, G. dracula and G. spinosa, plus three others left in open nomenclature, are described from the late Frasnian of Western Australia. A further species of Gondwanaspis, G. prisca, is described from the early Frasnian of Montagne Noire. Species of Gondwanaspis are shown to possess a number of paedomorphic features. A functional analysis suggests that, unlike other odontopleurids, Gondwanaspis actively fed and rested with the same cephalic orientation. The sole odontopleurid survivors of the severe terminal mid-Givetian biocrisis (‘Taghanic Event’) belong to the koneprusiine Koneprusia in the late Givetian and Frasnian, and, of cryptogenic origin, the acidaspidine Gondwanaspis in the Frasnian. Whereas the former became extinct in the late Frasnian at the Lower Kellwasser Event, the latter disappeared, and with it the entire Odontopleuroidea, at the terminal Frasnian Upper Kellwasser global biocrisis.

scholarly journals Morphological and allozyme studies of midwife toads (genus Alytes), including the description of two new taxa from Spain

1995 ◽  
Vol 65 (1) ◽  
pp. 5-34 ◽  
Author(s):  
J.W. Arntzen ◽  
M. García-París
Keyword(s):  
Phylogenetic Analysis ◽  
New Species ◽  
Discriminant Analysis ◽  
Morphological Variation ◽  
Principal Component ◽  
Allozyme Variation ◽  
Sister Taxon ◽  
Allozyme Data ◽  
Remarkable Similarity ◽  
A New Species

Allozyme variation in 31 to 50 presumptive loci of 12 populations of European midwife toads of the genus Alytes show appreciable genetic divergences (DNei from 0.29 to 0.72) among four groups. These groups correspond to A. cisternasii Boscá, 1879, A. obstetricans (Laurenti, 1768), A. muletensis (Sanchiz & Adrover, 1979), and a new species from the Betic mountains described here as A. dickhilleni n. sp. Smaller divergences among geographic groups of populations of A. obstetricans (up to DNei = 0.17) support the existence of three geographic units in Europe corresponding to the previously recognized subspecies A. o. obstetricans and A. o. boscai Lataste, 1879, plus a third one described here under the designation of A. o. almogavarii n. ssp. The analysis of morphological variation among taxa using principal component and discriminant analysis shows a remarkable similarity between A. dickhilleni and A. obstetricans; these are cryptic species. A phylogenetic analysis of allozyme data using A. cisternasii as the outgroup supports a sister taxon relationship between A. muletensis and A. dickhilleni, with A. obstetricans the sister taxon to this clade. The historical biogeography of the genus is discussed.

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