RECONSTRUCTION OF AN APPARATUS OF NEOSTRACHANOGNATHUS TAHOENSIS FROM ORITATE, JAPAN AND SPECIES OF NEOSTRACHANOGNATHUS FROM OMAN

Authors: AGEMATSU, SACHIKO¹; ORCHARD, MICHAEL J.²; SASHIDA, KATSUO¹

Source: Palaeontology, Volume 51, Number 5, September 2008 , pp. 1201-1211(11)

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Abstract:

The apparatus of an Early Triassic conodont Neostrachanognathus tahoensis Koike, 1998 from Oritate, Kumamoto Prefecture, Japan, and a species of Neostrachanognathus from Oman were reconstructed. On the basis of five natural assemblages from the Oritate area, the three-dimensional apparatus model of N. tahoensis is interpreted as bilaterally symmetrical and composed of 14 elements consisting of pairs of P₁, P₂, P₃, S₁, S₂, S₃, and S₄ elements. The P₁ and P₂ elements are coniform elements, the P₃ elements are digyrate forms, and the S elements are bipennate ramiforms. The S elements are arranged rostrally in the apparatus and the pairs of the P₁, P₂, and P₃ elements are subvertically arranged caudally and ventrally to the S array. One of the natural assemblages was formed by rostrocaudal collapse of the apparatus on the sea floor, whereas the other assemblages indicate that conodont animals came to rest nearly parallel with the substrate prior to burial. A collection of isolated elements from Jabal Safra, Oman, includes a second species of Neostrachanognathus with a comparable apparatus.

Keywords: Apparatus; conodont; Japan; natural assemblage; Oman; Triassic

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1475-4983.2008.00804.x

Affiliations: 1: Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, 305-8572, Japan;, Email: agematsu@geol.tsukuba.ac.jp 2: Geological Survey of Canada, 625 Robson St., Vancouver, BC, V6B 5J3, Canada

Publication date: 2008-09-01