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New observations on the squamation patterns of articulated specimens of Loganellia scotica (Traquair, 1898) (Vertebrata: Thelodonti) from the Lower Silurian of Scotland

Živile ŽIGAITE & Daniel GOUJET

en Geodiversitas 34 (2) - Pages 253-270

Published on 29 June 2012

Articulated squamations ofLoganellia scotica (Traquair, 1898) from the Lower Silurian Lesmahagow inliers of southern Scotland have been studied. They include seven articulated specimens, three of them representing complete thelodont fossils, and four partially preserved postpectoral, precaudal and caudal parts of the exoskeleton. All the five main types of thelodont scales that is rostral, cephalo-pectoral, postpectoral, precaudal and pinnal sacles, as well as respective squamation patterns have been observed on articulated specimens. The specific orbital, branchial, and bucco-pharyngeal scales, characteristic of L. scotica, have not been found due to the poor or non-preservation of these particular areas within the specimens studied. Tail morphology and squamation pattern of the caudal fin have been studied with particular attention, and the constitution of the caudal fin rays has been analyzed. The rostral squamation pattern is argued to be characteristic to L. scotica.

Keywords :

Thelodonti, articulated squamation, thelodonts, early vertebrates, Lower Silurian, Scotland

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