Fische aus dem Campan (Oberkreide) der Bohrung Metelen 1001 (Münsterland, NW-Deutschland)

Zusammenfassung

Im Fossilmaterial der Forschungsbohrung Metelen 1001 sind diverse Selachier- und Teleostier-Reste (vor allem Kieferzähne) vertreten. Wichtigste Faunenelemente sind Squalidae, Triakidae und Enchodontidae. Folgende Selachier wurden ermittelt:Squalus vondermarcki Müller & Schöllmann, 1989;Centroscymnus praecursor Müller & Schöllmann, 1989;Cretascymnus westfalicus Müller & Schöllmann, 1989,Paratriakis decheni (von der Marck 1863) undScyliorhinus sp. Eine kurze Diskussion paläoökologischer Fragen ergänzt die Bemerkungen zu den bestimmbaren Selachier-Taxa.

Summary

In the well Metelen 1001 debris of fishes (e.g. teeth of selachians and teleosteans) are present. The teeth of selachians are briefly described. Most important groups are Squalidae, Triakidae, and Enchodontidae. The following selachians can be observed:Squalus vondermarcki Müller & Schöllmann, 1989;Centroscymnus praecursor Müller & Schöllmann, 1989;Cretascymnus westfalicus Müller & Schöllmann, 1989,Paratriakis decheni (von der Marck, 1863), andScyliorhinus sp. Based on the identified selachian taxa a short paleoecological discussion completes this paper.

The small collection of selachian teeth mainly consists of neritic elements:Squalus vondermarcki (most common species),Paratriakis decheni, andScyliorhinus sp. True deepwater-Squalidae are very rare and restricted on some layers in the intervall of about 65 to about 100 meter.

In one sample (43,0–43,1 m) 12 teeth ofSqualus vondermarcki were collected. This is a large number in relation to the size of the sample. The cause für the accumulation of teeth can be:

• 1. A rich population as a result of optimal environmental conditions (temperature, oxygen). Squalus prefers cool waters common in upwelling areas.

• 2. A rich population as a result of high biological productivity, very common in areas of upwelling or collision of currents with very different temperature levels.

• 3. Very low sedimentation (condensation).

• 4. Postmortal processes (reworking and concentration of teeth).

TheSqualus-teeth of the sample 43,0–43,1 m do not show any traces of prefossilization and reworking. Traces of condensation are lacking. The rich population probably is caused by optimal trophic and temperature conditions in upwelling areas.

The occurrence of some rare deepwater-Squalidae (Cretascymnus andCentroscymnus) is connected with microfaunas indicating upwelling and very cool temperatures (seeLommerzheim, this volume). In the center of the Westphalian Creatceous Basin both genera are the most common selachians in beds of higher Campanian age. During times of upwelling some of the deepwater sharks entered shallower coastal areas following the upwelling cooler deep water.

Scyliorhinus andParatriakis are neritic faunal elements and common in shelf sediments of Upper Cretaceous age. Their occurrence in the samples is in accordance to the interpretation of the microfaunas (Lommerzheim, this volume). The teeth of Enchodontidae are very common. These teleosteans were fast swimming predators of the pelagical realm like the living Scombridae. The teeth of this mostly epipelagical fishes belong to the most frequent fish remains in late Cretaceous sediments, in neritic to pelagic areas.