University of Bonn researcher Klaus Wolkenstein has examined the fossilized specimens of the Triassic scallop species Pleuronectites laevigatus with preserved color patterns.
UV light-induced fluorescence revealing residual color patterns in Pleuronectites laevigatus: (A-B) left valve with broad radial color bands showing continuation of bands after a growth line only under UV light, Upper Muschelkalk, Trochitenkalk Formation, Germany; (C-D) left valve with zigzag pattern, Upper Muschelkalk, Germany; (A, C) specimens under normal light; (B, D) specimens under UV light; note that in adult specimens of the species auricles are often not preserved. Scale bars – 1 cm. Image credit: Klaus Wolkenstein, doi: 10.1111/pala.12625.
Ultraviolet (UV) light, which is invisible to the human eye, excites organic compounds in the fossils causing them to glow.
This reveals a surprising variety of color patterns: different variations of stripes, zigzags and flame patterns.
The diversity of color patterns is similar to those of today’s seashells found on a beach. However, the color patterns of today’s scallops do not show any fluorescence.
“UV light-induced fluorescence is widely used as a key to reveal residual shell color patterns of ancient mollusks,” Dr. Wolkenstein said.
“However, only few examples of fluorescent color patterns are known from Mesozoic marine shells and little is known about the nature of fluorescence in fossils.”
For the present study, the author focused on Pleuronectites laevigatus, an ancient scallop species from the Middle Triassic Muschelkalk of Central Europe.
He investigated a total of 120 specimens of Pleuronectites laevigatus with preserved color patterns (out of several hundred without coloration).
The majority of Pleuronectites laevigatus’ color patterns displayed distinct yellowish orange to reddish orange fluorescence under long-wave UV light.
“In the case of the Triassic shells, fluorescent compounds were only formed in the course of fossilization through oxidation of the original pigments,” Dr. Wolkenstein said.
“Surprisingly, the fossil shells show different fluorescent colors, depending on the region where they were found.”
“The color spectrum ranges from yellow to red with all the transitions in between, which suggests that there were clear regional differences in the fossilization of these scallops.”
The findings were published October 27, 2022 in the journal Palaeontology.
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Klaus Wolkenstein. Fluorescent colour patterns in the basal pectinid Pleuronectites from the Middle Triassic of Central Europe: origin, fate and taxonomic implications of fluorescence. Palaeontology, published online October 27, 2022; doi: 10.1111/pala.12625
Source link: https://www.sci.news/paleontology/pleuronectites-laevigatus-fluorescence-11355.html
