<i>Elegestolepis</i>and its kin, the earliest monodontode chondrichthyans

Andreev, Plamen S.; Coates, Michael I.; Karatajūtē-Talimaa, Valentina; Shelton, Richard M.; Cooper, Paul R.; Sansom, Ivan J.

doi:10.1080/02724634.2017.1245664

Cited by 16 publications

(15 citation statements)

References 77 publications

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“…S13). These records suggest a global, mid-shelf center for sampling and diversity, and a null expectation of originations in deep subtidal and reef environments (more so than expected from previous studies focused on reef-bearing facies (15)). This is in stark contrast with shallower gnathostome ancestral habitats ( Fig.…”

mentioning

confidence: 49%

“…Biogeographic patterns suggest that body-form divergence occurred in multiple shallow settings, increasing overall diversity. Micromeric forms occur alongside macromeric astraspids in the Ordovician of Laurentia, while robust galeaspids existed alongside gracile chondrichthyans in the early Silurian of Gondwana (4)(5)(6)(7)15,17,24,27,28).…”

Section: Endemicity In Coastal Waters May Have Later Promoted Originamentioning

confidence: 99%

“…Silurian oceans, away from local competition, leading to further diversification in nearshore settings elsewhere (1,15,28). In contrast, benthic groups showed structured geographic patterns (27), moving along coastlines and inshore, perhaps towards nutrient inputs essential to their likely bottom-feeding and filtering lifestyles and away from…”

Section: Nektonic Body Plans Developed In These Hotspots Enabled Dispmentioning

confidence: 99%

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The Nearshore Cradle of Early Vertebrate Diversification

Sallan¹,

Friedman²,

Sansom³

et al. 2018

Geological Society of America Abstracts With Programs

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Ancestral vertebrate habitats are subject to controversy, and obscured by limited, often contradictory, paleontological data. We assembled fossil vertebrate occurrence and habitat datasets spanning the mid-Paleozoic (480-360 Mya) and found that early vertebrate clades, both jawed and jawless, originated in restricted, shallow intertidal-subtidal environments. Nearshore divergences gave rise to body plans with different dispersal abilities: robust fishes shifted more shoreward while gracile groups moved seaward. Freshwaters were invaded repeatedly, but movement to deeper waters was contingent upon form, and short-lived until the later Devonian. Our results contrast with the onshore-offshore trends, reef-centered diversification, and mid-shelf clustering observed in benthic invertebrates. Nearshore origins for vertebrates may be linked to the demands of their mobility, and influenced the structure of their early fossil record and diversification. One sentence summary: Early vertebrates diversified in restricted, shallow marine waters, with nearshore divergence in body form shaping their dispersal and fossil record.

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mentioning

confidence: 49%

Section: Endemicity In Coastal Waters May Have Later Promoted Originamentioning

confidence: 99%

Section: Nektonic Body Plans Developed In These Hotspots Enabled Dispmentioning

confidence: 99%

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The Nearshore Cradle of Early Vertebrate Diversification

Sallan¹,

Friedman²,

Sansom³

et al. 2018

Geological Society of America Abstracts With Programs

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“…This 50-million-year record pre-dates the first appearance of teeth and articulated skeletons ( Leonodus and Celtiberina Botella, Donoghue & Martínez-Pérez , 2009 ; Doliodus Miller, Cloutier & Turner , 2003 ; Maisey, Miller & Turner , 2009 and Antarctilamna Young , 1982 ) of traditionally recognized chondrichthyans (euchondrichthyans sensu Pradel et al , 2014 ), as well as body fossils of acanthodian-grade stem chondrichthyans ( Brazeau & Friedman , 2015 and references therein). These, largely microscopic, remains include the elegestolepids ( Karatajūtė-Talimaa , 1973 ; Žigaitė & Karatajūtė-Talimaa , 2008 ; Andreev et al , in press ), sinacanthids ( Zhu , 1998 ; Sansom, Wang & Smith , 2005 ; Zeng , 1988 ), taxa such as Tezakia and Canyonlepis from the Ordovician of North America ( Sansom, Smith & Smith , 1996 ; Andreev et al , 2015 ), Tantalepis ( Sansom et al , 2012 ), Kannathalepis ( Märss & Gagnier , 2001 ) and Pilolepis ( Thorsteinsson , 1973 ), and, perhaps the most widely distributed and diverse collection of what Ørvig and Bendix-Almgreen, quoted in Karatajūtė-Talimaa ( 1995 ), referred to as ‘praechondrichthyes,’ the mongolepids ( Karatajūtė-Talimaa et al , 1990 ; Karatajūtė-Talimaa & Predtechenskyj , 1995 ; Sansom, Aldridge & Smith , 2000 ). It is the latter which this work concentrates on, re-assessing and re-defining previously described members of the Mongolepidida, and describing a new taxon that extends the range of the Order into the Ordovician, adding further evidence for a diversification of early chondrichthyans as part of the Great Ordovician Biodiversification Event that encompasses a wide variety of taxa, both invertebrate (e.g., Webby, Paris & Droser , ...…”

Section: Introductionmentioning

confidence: 99%

The systematics of the Mongolepidida (Chondrichthyes) and the Ordovician origins of the clade

Andreev

Coates

Karatajūtē-Talimaa

et al. 2016

PeerJ

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The Mongolepidida is an Order of putative early chondrichthyan fish, originally erected to unite taxa from the Lower Silurian of Mongolia. The present study reassesses mongolepid systematics through the examination of the developmental, histological and morphological characteristics of scale-based specimens from the Upper Ordovician Harding Sandstone (Colorado, USA) and the Upper Llandovery–Lower Wenlock Yimugantawu (Tarim Basin, China), Xiushan (Guizhou Province, China) and Chargat (north-western Mongolia) Formations. The inclusion of the Mongolepidida within the Class Chondrichthyes is supported on the basis of a suite of scale attributes (areal odontode deposition, linear odontocomplex structure and lack of enamel, cancellous bone and hard-tissue resorption) shared with traditionally recognized chondrichthyans (euchondrichthyans, e.g., ctenacanthiforms). The mongolepid dermal skeleton exhibits a rare type of atubular dentine (lamellin) that is regarded as one of the diagnostic features of the Order within crown gnathostomes. The previously erected Mongolepididae and Shiqianolepidae families are revised, differentiated by scale-base histology and expanded to include the genera Rongolepisand Xinjiangichthys, respectively. A newly described mongolepid species (Solinalepis levis gen. et sp. nov.) from the Ordovician of North America is treated as family incertae sedis, as it possesses a type of basal bone tissue (acellular and vascular) that has yet to be documented in other mongolepids. This study extends the stratigraphic and palaeogeographic range of Mongolepidida and adds further evidence for an early diversification of the Chondrichthyes in the Ordovician Period, 50 million years prior to the first recorded appearance of euchondrichthyan teeth in the Lower Devonian.

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“…The taxa identified here are placed within the total-group Chondrichthyes and add to the burgeoning diversity of Lower Palaeozoic scales that are shark-like in their overall appearance, growth and histology. These include, in approximate stratigraphic order from the Darriwilian (Middle Ordovician) through to the Lower Devonian, Tantalepis [16], Tezakia and Canyonlepis [7,17], mongolepids [5,[18][19][20], elegestolepids [20,21] and Tuvalepis [22]. The relationship of these taxa to conventionally defined chondrichthyans (sensu [23]) remains contentious despite recent progress in integrating scale-based trees into the phylogenetic framework of early jawed gnathostomes [24].…”

Section: Introductionmentioning

confidence: 99%

Early Silurian chondrichthyans from the Tarim Basin (Xinjiang, China)

et al. 2020

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The Sinacanthida ordo nov. and Mongolepidida are spine-and scale-based taxa whose remains encompass some of the earliest reported fossils of chondrichthyan fish. Investigation of fragmentary material from the Early Silurian Tataertag and Ymogantau Formations of the Tarim Basin (Xinjiang Uygur Autonomous Region, China) has revealed a diverse mongolepidid and sinacanthid fauna dominated by mongolepids and sinacanthids in association with abundant dermoskeletal elements of the endemic 'armoured' agnathans known as galeaspids. Micro-computed tomography, scanning electron microscopy and histological sections were used to identify seven mongolepid genera (including Tielikewatielepis sinensis gen. et sp. nov., Xiaohaizilepis liui gen. et sp. nov. and Taklamakanolepis asiaticus gen. et sp. nov.) together with a new chondrichthyan (Yuanolepis bachunensis gen. et sp. nov.) with scale crowns consisting of a mongolepid-type atubular dentine (lamellin). Unlike the more elaborate crown architecture of mongolepids, Yuanolepis gen. nov. exhibits a single row of crown elements consistent with the condition reported in stem chondrichthyans from the Lower Devonian (e.g. in Seretolepis, Parexus). The results corroborate previous work by recognising lamellin as the main component of sinacanthid spines and point to corresponding developmental patterns shared across the dermal skeleton of taxa with lamellin and more derived chondrichthyans (e.g. Doliodus, Kathemacanthus, Seretolepis and Parexus). The Tarim mongolepid fauna is inclusive of coeval taxa from the South China Block and accounts for over two-thirds of the species currently attributed to Mongolepidida. This demonstrates considerable overlap between the Tarim and South China components of the Lower Silurian Zhangjiajie Vertebrate Fauna.

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Elegestolepisand its kin, the earliest monodontode chondrichthyans

Cited by 16 publications

References 77 publications

The Nearshore Cradle of Early Vertebrate Diversification

The Nearshore Cradle of Early Vertebrate Diversification

The systematics of the Mongolepidida (Chondrichthyes) and the Ordovician origins of the clade

Early Silurian chondrichthyans from the Tarim Basin (Xinjiang, China)

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