A coded utilitarian system for identifying Paleozoic ichthyoliths

Tway, Linda E.

doi:10.1080/02724634.1984.10011974

Cited by 6 publications

(4 citation statements)

References 8 publications

(3 reference statements)

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“…Terminology and identification of denticles follows mainly the code developed by Tway (1979Tway ( , 1984 and as applied by Johns (1996). An attempt is made to assess the variation by comparing it to extant and fossil shark species and to the framework of formal taxa introduced by Johns et al (1997).…”

Section: Methodsmentioning

confidence: 99%

“…The sample of dermal denticles can be subdivided in groups and some can be tentatively identified either by following the coded systems of ichthyoliths (Doyle et al 1974;Tway 1979Tway , 1984Johns et al 1997) or by comparison to other reports on (more or less contemporaneous) elasmobranch denticles.…”

Section: P R O V a Smentioning

confidence: 99%

“…Type A is indistinguishable from type B according to the system provided by Tway (1979Tway ( , 1984 because of the lack of codes for the accessory 1-3 cusplets on the mesial platform (ridge). These cusplets may rarely preserve and may therefore be …”

Section: P R O V a Smentioning

confidence: 99%

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Pyknotylacanthus spathianus gen. et sp. nov., a new ctenacanthoid from the Early Triassic of Bear Lake (Idaho, USA)

Mutter¹

2005

RBP

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-A fairly completely preserved finspine recovered in association with dermal denticles from the Early Triassic of Bear Lake County (Idaho, USA) represents the youngest unequivocal record of a Bythiacanthuslike shark (Ctenacanthoidea incertae sedis). The accompanying invertebrate fauna indicates a late Early Spathian age (Early Triassic). Comparison of the finspine with sparse Late Paleozoic records allows identification of predominantly plesiomorphic, "ctenacanthoid" characters such as shape and cross-section of the finspine, the concave posterior wall, and the stellate morphology of the tubercles. One presumably derived character, the large and densely spaced tubercles with reduced ornament, distinguishes Pyknotylacanthus gen. nov. from its Carboniferous predecessors. It is suggested that "Cosmacanthus humboldtensis" from the Middle Triassic West Humboldt range (Nevada, USA) may represent an even younger member of the same lineage. The sample of associated dermal denticles is difficult to interpret but believed to belong at least in part to the same individual. The variability of denticles exceeds the range of expected individual variation, and is discussed in detail.

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Section: Methodsmentioning

confidence: 99%

Section: P R O V a Smentioning

confidence: 99%

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Pyknotylacanthus spathianus gen. et sp. nov., a new ctenacanthoid from the Early Triassic of Bear Lake (Idaho, USA)

Mutter¹

2005

RBP

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“…Both actinopterygian and sarcopterygian fish are known from the site, mostly in the form of ichthyoliths, which are defined as microscopic skeletal remains of fish, mainly dermal denticles, scales, and teeth (Tway, 1984;Tway et al, 1986). Actinopterygian fish specimens are by far the most abundantly preserved vertebrate elements at Mile 175.…”

Section: Osteichthyes Actinopterygiimentioning

confidence: 99%

Ichthyoliths and other microvertebrate remains from the Morrison Formation (Upper Jurassic) of northeastern Wyoming: A screen-washed sample indicates a significant aquatic component to the fauna

Foster¹,

Heckert

2011

Palaeogeography, Palaeoclimatology, Palaeoecology

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A screenwashed microvertebrate site, the Mile 175 locality, in the Morrison Formation of Wyoming has yielded more than 3000 elements of actinopterygian fish and indicates that fish were not as rare in some parts of the formation as previously supposed. Actinopterygians are represented by diverse teeth and tooth-bearing bone fragments, fin elements, and thousands of scales and scale fragments that can be divided into three distinct morphotypes. Lungfish are rare, represented by nine toothplates and toothplate fragments that are provisionally assigned to Potamoceratodus. Tetrapods recovered from the Mile 175 locality include indeterminate salamanders, turtles, choristoderes, a squamate, goniopholid crocodyliforms, theropod and ornithopod dinosaurs, and several mammals, including Docodon and indeterminate multituberculates. Salamanders are represented by just a few indeterminate vertebrae. The turtle fauna includes numerous small shell fragments and limb elements. The authors assign a tooth-bearing jaw fragment and several vertebrae to the choristodere Cteniogenys, whereas a sole vertebra is the only squamate fossil recovered. Theropod dinosaurs are well represented by several teeth, as is the ornithopod dinosaur Othnielosaurus. Similarly, several mammalian tooth and jaw fragments can be referred to either Docodon or Multituberculata indet. Dominance of the sample by aquatic and semi-aquatic taxa suggests the paleodepositional environment was a permanent water source. Many of the specimens appear to represent small and presumably ontogenetically young individuals of larger, known taxa in the Morrison Formation, and the site includes the northernmost occurrences of several taxa in the formation. Screenwashing efforts at several other previously quarried large-vertebrate sites in the Morrison Formation have shown promising results for recovering previously unidentified taxa.

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Determination Methods for the Exoskeletal Remains of Early Vertebrates

Karatajūtē-Talimaa¹

2008

Fossil Record

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The exoskeleton, consisting of micromeric elements (odontodes) and their derivatives, is characteristic of the most ancient vertebrates. Great morphological and histological variability of discrete exoskeletal microremains makes it difficult to identify them. It is necessary to study not only separate scales or tesserae, but also to get a picture of the squamation in general, because species determined from discrete elements are understood as an assemblage of morphological types. For determination of discrete exoskeletal elements, their morphology, internal structure, defined tissue types of crown and basal plate, types (way) of their growth, system of vascular canals should be studied in addition changes occuring during ontogenetic development of both the dermal skeletal elements and the squamation should be taken in consideration. The material of different groups of early vertebrates (astraspids, tesakoviaspids, heterostracans, thelodonts, mongolepids, chondrichthyans and acanthodians), which were widely distributed in the Early Palaeozoic, are used as examples. ZusammenfassungEin Hautskelett aus mikromerischen Elementen (Odontodes) und davon abgeleiteten Formen ist fur die meisten fruhen Vertebraten kennzeichnend. GroBe rnorphologische und histologische Variabilitat der einzelnen Mikroreste des Hautskeletts bereitet bei ihrer Bestimmung Schwierigkeiten. Es ist notwendig, nicht nur isolierte Schuppen und Tesserae zu untersuchen, sondern man mu13 sich eine Vorstellung der gesamten Beschuppung verschaffen, da Arten bestimmt auf isoliertem Material als eine Ansammlung von morphologischen Typen verstanden werden mussen. Bei der Bestimmung isolierter Elemente des AuRenskeletts sollte man deren Morphologie, innere Struktur, Gewebetypen der Krone und Basalplatte, Arten des Wachstums, Anordnung der GefaBkanale und Veranderungen wahrend des Wachstums des Einzelelements und der Gesamtbeschuppung beriicksichtigen. Hautskelett-Elemente der verschiedenen Gruppen fruher Vertebraten (Astraspiden, Tesakoviaspiden, Heterostraken, Thelodontier, Mongolepiden, Chondrichthyer und Acanthodier), die im fruhen Palaozoikum weit verbreitet sind, werden als Beispiele benutzt.

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A coded utilitarian system for identifying Paleozoic ichthyoliths

Cited by 6 publications

References 8 publications

Pyknotylacanthus spathianus gen. et sp. nov., a new ctenacanthoid from the Early Triassic of Bear Lake (Idaho, USA)

Pyknotylacanthus spathianus gen. et sp. nov., a new ctenacanthoid from the Early Triassic of Bear Lake (Idaho, USA)

Ichthyoliths and other microvertebrate remains from the Morrison Formation (Upper Jurassic) of northeastern Wyoming: A screen-washed sample indicates a significant aquatic component to the fauna

Determination Methods for the Exoskeletal Remains of Early Vertebrates

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