PHYLOGENETIC ANALYSIS OF DEVONIAN TROPIDOCORYPHID TRILOBITES (ORDER PROETIDA), AND RELATIONSHIPS OF TROPIDOCORYPHE & ASTYCORYPHE

Complete specimens of Tropidocoryphe, a rare trilobite genus, are found in Devonian rocks of Morocco. This genus is in need of revision. It is identified by a tropidium, together with marginal widening of the cephalon, and distinct forward divergence of anterior branches of facial sutures. Since being described by Novak (1890), a number of Tropidocoryphe species have been proposed from partial or imperfect specimens. To further complicate matters, there are a number of similar genera within the Tropidocoryphidae that are similar to Tropidocoryphe. One such genus, Astycoryphe (Richter & Richter, 1919), is only differentiated from Tropiodocoryphe by less divergent anterior sutures and cephalic border ridges.

Newly discovered well-preserved, complete Moroccan tropidocoryphids were identified to generic level. One Moroccan species displays character states of both Tropidocoryphe and Astycoryphe. Given the similarity of these genera, a phylogenetic analysis of morphologically similar species of Tropidocoryphidae was undertaken to determine the relationships of these genera, and the genus of this species. Preliminary results suggest that it is an Astycoryphe. With these findings, the relationships of Astycoryphe and Tropidocoryphe are reviewed, and Tropidocoryphidae evolution during the Early and Middle Devonian is discussed.

Furthermore, the phylogenetic analysis permits the relationships and validity of examined taxa to be considered. Ultimately, results of this analysis and new Moroccan specimens will play a significant role in understanding trilobite evolution through the Devonian.

References:

Novák, O. 1890. Vergleichende Studien an einigen Trilobiten aus dem herzyn von Bicken, Wildungen, Greifenstein, und Böhmen. Palaeont. Abh. 3: 95-138.

Richter R. & Richter E. 1919. Proetiden aus neueren Aufsammlungen im vogtländischen und sudetischen Oberdevon. Senckenbergiana 1: 97-130.1.25