Gondwanan cyrtocrinids uncover hidden diversity and crinoid dispersal pathways

TL;DR

New Jurassic crinoid fossils from Algeria reveal hidden diversity and dispersal patterns of cyrtocrinids in Gondwana.

Contribution

The study presents the first Southern Hemisphere cyrtocrinid fossils, expanding the geographic and temporal range of key genera.

Findings

New cyrtocrinid material from Algeria represents three taxa, including the first Southern Hemisphere occurrence.

The findings extend the earliest known appearances of Apsidocrinus and Tetracrinus to the Callovian and Oxfordian.

Integration of Gondwanan records reveals new palaeobiogeographic linkages in the southern Tethyan and palaeo-Pacific margins.

Abstract

The post-Palaeozoic crinoid order Cyrtocrinida exhibits remarkable morphological diversity and ecological versatility, yet its fossil record from southern continents remains fragmentary and poorly understood. In this study, we document new cyrtocrinid material from the Jurassic of Algeria, representing three taxa, including the first unequivocal cyrtocrinid occurrence from the Southern Hemisphere segment of the Gondwanan margin. These specimens substantially expand both the geographic and stratigraphic ranges of key genera, most notably Apsidocrinus and Tetracrinus, pushing their earliest appearances from the Kimmeridgian back to the Callovian and Oxfordian, respectively. Integration of these Algerian occurrences with Gondwanan records from Madagascar, New Zealand, and Peru reveals previously unrecognized palaeobiogeographic linkages along the southern Tethyan and palaeo-Pacific margins. Collectively, our findings expose significant gaps in the southern cyrtocrinid fossil record and demonstrate the potential for new discoveries to refine current models of their evolutionary history, dispersal pathways, and palaeobiogeographic dynamics.

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