Abstract:
Encrinurids are common in Ordovician and Silurian strata but whether they survived into the
Early Devonian is still controversial. This paper documents the encrinurid Batocara sp. near the
Silurian–Devonian boundary in western Junggar, Xinjiang. The highest horizon of Batocara sp.
is located above the first appearance datum of the Devonian conodont Caudicriodus,
confirming that encrinurids may cross the Silurian–Devonian boundary. The presence of
Caudicriodus angustoides bidentatus, Zieglerodina planilingu and plate-type loboliths of
scyphocrinoids above the highest horizon of Batocara sp. indicates that encrinurids here extend
only into the lower part of the first conodont zone of the Lochkovian (i.e., Caudicriodus
hesperius Biozone). Encrinurids are widely distributed and easily recognized, and unlike
graptolites and conodonts are not controlled by lithofacies. Therefore, it might be possible to
use the highest horizon of encrinurids as indicator fossils to identify the approximate position of
the Silurian–Devonian boundary in areas or sections where graptolites and conodonts are not
present, and at least in northwest China.
