Lumbricaria
Lumbricaria is a trace fossil that is interpreted as the petrified feces ( coprolite ) of cephalopods (Cephalopoda). This trace genus (Ichnogenus) occurs in the Solnhofen limestone and various other, similar limestone deposits. It is one of the relatively common fossils in the Solnhofen limestone limestone.
description
It is a string-like structure, often entwined in piles. The diameter of the cords is 1-4 mm, their length varies and in extreme cases reaches 170 cm. The cords have a rough surface and tapers at irregular intervals. Lumbricaria consists almost exclusively of the calcitic remains of the free-swimming sea lily Saccocoma .
Interpretations
The origin of these structures was disputed for a long time, mainly because the determination of the organic components was not possible for a long time. In the 18th century and the beginning of the 19th century, they were often mistaken for worms, which is also referred to by the name Lumbricaria ( Latin lumbricus - "earthworm"). Doubts were soon voiced about this interpretation - as an anonymous author noted in 1830 that the strings were structured irregularly and not regularly, as would be expected in worms. As an alternative interpretation it was suggested that it could have been the ejected entrails of sea cucumbers - this interpretation is based on a fossil from the Solnhofen limestone, which shows a lumbricaria located directly next to a supposed sea cucumber . Later it turned out that the supposed sea cucumber was actually a soft sponge . Another interpretation, popularized by Agassiz (1833), interprets Lumbricaria as fish intestines. This interpretation is based on the observation that in dead fish that float on the surface of the water due to gases accumulated in the abdominal region, the abdomen occasionally bursts open, with the entrails being released into the water column.
The interpretation generally accepted today comes from Janicke (1970) and interprets Lumbricaria as the excrement of cephalopods such as ammonites or squids . Janicke argues that due to the saccocoma remains it must be coprolites. The producers must also have been free-swimming animals, since bottom-dwelling animals from the Solnhofen limestone have hardly been passed on. This author contradicts interpretations that interpret Lumbricaria as fish excrement, since this excrement is mostly phosphatic . The cephalopods, like Lumbricaria, would belong to the common fossils of the Solnhofen limestone limestone; in addition, the excrement of the recent genus Octopus would have a similar shape.
supporting documents
- ↑ a b c d Volkmar Janicke: Lumbricaria - a cephalopod coprolite . In: N. Jb.Geol.Paleont. Mh., Fossil deposits . No. 3 . Stuttgart 1970, p. 50-60 .
- ↑ a b c d Gerd Dietl, Günter Schweigert: In the realm of the sea angels - The Nusplinger Plattenkalk and its fossils . Publishing house Dr. Friedrich Pfeil, Munich 2001, ISBN 3-931516-90-3 , p. 134 .
- ^ Christopher Duffin: "Records of warfare ... embalmed in the everlasting hills": a History of Early Coprolite Research . In: Mercian Geologist . tape 17 , no. 2 , 2009, p. 109 .