Juvenile eucladid crinoid from the Middle Devonian of Turkey

William I. AUSICH & M. Cemal GÖNCÜOĞLU

en Geodiversitas 42 (14) - Pages 215-221

Published on 11 June 2020

A microcrinoid-sized eucladid crinoid (Eucladida Wright, 2017) is described from the Yığınlı Formation (Devonian, Famennian) in the Büyük Zap Anticline in the Hakkari region of SE Turkey. Compared to other eucladids of similar size, the Yığınlı Formation specimen is at a quite advanced morphological stage with arms present through at least the secundibrachials. Early post-larval development is a key for understanding homologies among crinoid clades; however Paleozoic crinoids in the microcrinoid range (≤ 2.0 mm) are very rare. This specimen is either at a very advanced developmental stage for its size, or typical microcrinoids are neotenic.

Keywords :

Crinoid, Devonian, Famennian, Hakkari, southeastern Turkey

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