Megalodontoidea
" Kuhtritt " on the foundation stone of a hut at the former Lainl -Alm at Jachenau in the Bavarian Alps
- Worldwide
- Megalodontidae
- Dicerocardiidae
- Wallowaconchidae
Megalodonten ( superfamily Megalodontoidea ) are mostly large mussels ( Bivalvia ), which are expected to order Hippuritoida within the superorder Heterodonta. The best known representatives of this group are the so-called Kuhtrittmuscheln from the Triassic, which can be found today as fossils, for example, in the Dachstein limestone and similar rocks of the Northern Limestone Alps. The oldest member of the group appeared in the Ordovician. The superfamily died out in the Cretaceous.
Features
The housings are equivalve with a strongly developed and eingedrehtem vertebrae in the rule. Particularly striking is the fact that the " vortex " of the shell, so their older shell parts are not next to each other rolled, but squirm like a corkscrew and therefore point away from the center plane as Bock horns in some species. This is only visible in preparations, because of the rock surface, the shells are preserved in random cross sections, in any case where the surface layer is not parallel. The lock edge is formed into a wide lock plate containing only a few large teeth. Typical of Megalodonten is also a relatively thick to very thick shell. The ligament is external. The sphincters are usually non-uniform. The Megalodonten populated shallow, warm seas, often at the edge of reefs or in the Hinterriffbereichen. They lived well half buried in the sediment. Therefore, the shells are very often embedded in life position in the rock. It is believed that the Megalodonten lived much like modern giant clams of the Indian Ocean in symbiosis with algae, so harbored on their gills green algae, which supplied the shell with nutrients.
The Megalodonten in folklore
The Megalodonten the Upper Triassic are called " deer " in the vernacular - or designated " Kuhtritt ". They were interpreted as traces of the " Wild Hunt " or as footprints of " wild women "; in Swiss francs they were referred to as " Geißenfüßle ". This is related to the idea that forest spirits, albums and Druden had no human, but animal feet. These fossils were but also as a defense against the evil spell. Therefore, their use as foundation stones for huts like on the two adjacent photos of the Lainl -Alm is certainly no coincidence.
Conservation and protection
The Megalodonten almost always present in pure limestone, which was muddy to fine sand in their lifetime, and later turned to stone. They can not be solved by knocking out of the rock, without destroying it. For conservation reasons, it can not damage the solid rock in the mountains. Better therefore is the fossil search in quarries, about the stove Auersberg at Golling.
System
Currently three families are distinguished within the Megalodontoidea:
- Megalodontidae Moris & Lycett, 1853
- Dicerocardiidae Kutassy, 1934
- Wallowaconchidae Yancey & Stanley, 1999