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Noun1.heterostracan - extinct jawless fish with the anterior part of the body covered with bony plates; of the Silurian and Devonian
agnathan, jawless fish, jawless vertebrate - eel-shaped vertebrate without jaws or paired appendages including the cyclostomes and some extinct forms
Heterostraci, suborder Heterostraci - extinct group of armored jawless fishes or fish-like vertebrate; taxonomy is not clear
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References in periodicals archive ?
On the basis of a completely different shape of the scales, which is somewhat similar to heterostracan ribs, and the ultrasculpture pattern of the crown resembling both the furcacaudid and pteraspidid heterostracan ultrasculpture, the family Longodidae was established in an unknown (unnamed) order in the subclass Thelodonti.
It occurs together with the thelodont Phlebolepis elegans Pander, a heterostracan Archegonaspis sp., birkeniid anaspids, acanthodians Nostolepis striata Pander, Gomphonchus sandelensis (Pander), and Gomphonchus hoppei (Gross), and a taxon that has similarities with Thelodus parvidens Agassiz.
A similar model of skeletal development is also seen in a heterostracan Lepidaspis serrata Dineley & Loeffler, 1976: it possesses dentine ridges on the aspidin ridges, filled with aspidin trabeculae (Keating et al.
Pander in 1856, who described shields of the heterostracan Tolypelepis undulata, plates of the osteichthyan Lophosteus superbus and a number of jaw bones of acanthodians (Pander 1856).
A complete, articulated heterostracan from Wenlockian (Silurian) beds of the Delorme Group, Mackenzie Mountains, Northwest Territories, Canada.
Agnathan zones include mainly these of the psammosteid heterostracans. In the incomplete Lower Devonian sequence the Phialaspis (previous Traquairaspis) heterostracan Zone and the Skamolepis fragilis thelodont Zone have been recognized.
Using modern techniques, Tiiu Marss (Tallinn) and Valentina Karatajute-Talimaa (Vilnius) redescribe the late Silurian.early Devonian tessellated heterostracan Oniscolepis Pander, 1856 from the East Baltic and North Timan.
In the coarse-grained (diameter 0.5-2 mm) detrital material, heterostracan, placoderm, and sarcopterygian plate fragments are fairly worn.
Psammosteid heterostracans (Pteraspidomorpha) predominate in number among species-level taxa, but the specimens of antiarch placoderm remains are most numerous.
The first record was of fin spines and heterostracans from Pennsylvania by Claypole (1884, 1885); he assigned the fin spines ("small spines apparently of Selachian fish": Claypole 1885, p.