Upper Ordovician chondrichthyan‐like scales from North America

  title={Upper Ordovician chondrichthyan‐like scales from North America},
  author={Plamen S. Andreev and Michael I. Coates and Richard Shelton and Paul Cooper and M. Paul Smith and Ivan J. Sansom},
Studies of Ordovician micromeric fish scales from the Sandbian of North America have identified a number of scale‐based taxa potentially referable to the chondrichthyans and therefore can be among the stratigraphically oldest representatives of the clade described to date. Two of these, Tezakia hardingensis gen. et sp. nov. and Canyonlepis smithae gen. et sp. nov., are formally described herein. Tezakia gen. nov. scales are composed exclusively of tubular dentine and possess polyodontocomplex… 

Stem chondrichthyan microfossils from the Lower Old Red Sandstone of the Welsh Borderland

Placoid and polyodontode scales of stem chondrichthyans have been found in the early Lochkovian “Ditton Group” of the Brown Clee Hill district, Shropshire, England and at Talgarth, south Wales. One

Elegestolepis and Its Kin, the Earliest Monodontode Chondrichthyans

Elegestolepidida is established as the stratigraphically oldest chondrichthyan taxon to develop monodontode scales, which, in contrast to the ‘placoid’ scales of euselachians, are growing structures.

An early chondrichthyan and the evolutionary assembly of a shark body plan

Preliminary phylogenetic results highlight the likely convergent evolution of conventional chondrichthyan conditions among earliest members of this primary gnathostome division, while skeletal morphology points towards the likely suspension feeding habits of Gladbachus, suggesting a functional origin of the gill slit condition characteristic of the vast majority of living and fossil chondRichthyans.

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

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 and the Upper Llandovery–Lower Wenlock Yimugantawu (Tarim Basin, China), Xiushan (Guizhou Province, China) and Chargat (north-western Mongolia) Formations.

A revision of Vernicomacanthus Miles with comments on the characters of stem‐group chondrichthyans

Anatomic similarities between Vernicomacanthus and gyracanths may indicate the existence of a grade including these and similar acanthodian-grade taxa placed relatively crownwards in the chondrichthyan stem-group.

Evolutionary relationships among bullhead sharks (Chondrichthyes, Heterodontiformes)

This study emphasizes the importance of including non‐dental features in heterodontiform systematics (as compared with the use of dental characters alone) and supports the erection of the family †Paracestracionidae.

A new Silurian fish close to the common ancestor of modern gnathostomes

From body scale ontogeny to species ontogeny: Histological and morphological assessment of the Late Devonian acanthodian Triazeugacanthus affinis from Miguasha, Canada

Growth series of Palaeozoic fishes are rare because of the fragility of larval and juvenile specimens owing to their weak mineralisation and the scarcity of articulated specimens. This rarity makes

The oldest complete jawed vertebrates from the early Silurian of China

Two new species of well-preserved jawed fishes with complete bodies from the early Silurian period (Telychian age, around 436 million years ago) of Chongqing, South China are described, which reveal a previously unseen diversification of jawed vertebrates in the earlySilurian, and provide detailed insights into the whole-body morphology of the jawing vertebrates of this period.

The oldest gnathostome teeth

Direct evidence for the presence of jawed vertebrates in the early Silurian (around 439 million years ago) is provided by isolated tooth whorls of the gnathostome Qianodus duplicis from Guizhou province, China.



Chondrichthyan‐like scales from the Middle Ordovician of Australia

Microvertebrate sampling of the Stairway Sandstone has yielded scales that are chondrichthyan‐like in their overall construction, and Tantalepis gatehousei gen. et sp.

Ordovician microvertebrate remains from the Amadeus Basin, central Australia

ABSTRACT Microvertebrate remains are described from five formations (Pacoota Sandstone, Horn Valley Siltstone, Stairway Sandstone, Stokes Formation, Carmichael Sandstone) in the Ordovician sequence

New genus of chondrichthyans from the Silurian – Devonian boundary deposits of Tuva (Russia)

A new genus of Chondrichthyes from the uppermost Silurian–lowermost Devonian deposits of central Tuva (Russia) is described on the basis of the microremains (scales). A sample from the Khondergei

Chondrichthyan remains from the Lower Carboniferous of Muhua, southern China

The shallow water assemblage of chondrichthyan microremains, teeth, tooth plates and scales, from the middle Tournaisian (Mississippian) of the vicinity of Muhua village, Guizhou province, southern

Placoid scales (Chondrichthyes: Elasmobranchii) from the Late Jurassic (Kimmeridgian) of northern Germany

  • D. Thies
  • Environmental Science, Geography
  • 1995
ABSTRACT Bulk sampling of an Upper Jurassic (Kimmeridgian) section in front of the northern slope of the Harz mountains (northern Germany) has yielded a rich assemblage of elasmobranch placoid

Silurian and earliest Devonian birkeniid anaspids from the Northern Hemisphere

The sculpture of scales and plates of articulated anaspids from the order Birkeniida is described and used to clarify the position of scale taxa previously left in open nomenclature, supporting a new anaspid taxonomy that includes both articulated and disarticulated material.

Global Ordovician vertebrate biogeography

Ordovician fossils from wells in the Williston basin, eastern Montana


An entirely new type of rhombic fish scales has been discovered by Dr. A. Martinsson, Uppsala, in the Middle Ludlovian Hemse Beds of Gotland. Their morphology, histology, and growth are described.

A microvertebrate fauna from the Llandovery of South China.

Abstract The late Llandovery (early Silurian) of South China has yielded a locally abundant and diverse microvertebrate fauna. This includes scales of the little-known mongolepids, sinacanthid spines