These trilobites are very well preserved specimens of Kettneraspis from the world-famous “Red Cliff” site at Hamar Laghdad near Erfoud, Morocco. The fossils from this site are also known as “red fauna”. Like the trilobites, the rock is also reddish in colour, which is due to high concentrations of iron compounds. The shell of the trilobites is permeated by fine pores, which favour the process of silicification and thus the colouring. However, the eyes of the phacopids from this site in particular are sometimes  green in colour. The individual lenses of the trilobites consist of calcite, have a high magnesium content and no pore channels. This beautiful colouring of the shell makes the “red fauna” a unique group of fossils that clearly stand out among the usual trilobites.

The specimens shown here were acquired and prepared by me, handed over to Allart van Viersen for scientific work and donated to the Natural History Museum in Brussels.

Fig. 1: Kettneraspis freitagi, holotype, IRSNB a13909, in anterior (A),
lateral (B), oblique anterior (C), anterolateral (D), oblique posterior (E) and dorsal (F), scales: 5 mm, photos: Allart van Viersen

Fig. 2: Kettneraspis freitagi, paratype, IRSNB a13910, in dorsal (A),
oblique anterior (B), lateral (C), anterior (D), anterolateral (E) and oblique posterior (F), scales: 5 mm, photos: Allart van Viersen

Fig. 3: Kettneraspis freitagi, paratype, IRSNB a13911, in dorsal (A), close-up left posterolateral thorax and pygidium (B), anterior (C), oblique anterior (D), close-up left posterior (E), posterior (F), oblique lateral (G), pygidium (H) close-up right cheek spine (I), scales: 5 mm, except I: 2 mm, photos: Allart van Viersen

Fig. 4: Kettneraspis freitagi, paratype, IRSNB a13911, photo without whitening and natural shell colouration, photo: Paul Freitag

Fossil: Kettneraspis freitagi VAN VIERSEN 2024

Locality: Hamar Laghdad, “Red Cliff” (Morocco)

Formation: Lower to Middle Devonian, Emsian-Eifelian

Publication: VAN VIERSEN, A. (2024): Postcephalic segmentation and spines of the Siluro-Devonian odontopleurine trilobites Leonaspis Richter & Richter and Kettneraspis Prantl & Pribyl, with description of Bruthansovaspis gen. nov. from the Wenlock to Ludlow of the Prague Basin, in: Geologica Belgica, 2024, Vol. 27/1-2, S. 15–31.

Link to the article: https://popups.uliege.be/1374-8505/index.php?id=7157&lang=en