56 Paleolimnological Records of Climate and Environmental Change (Posters)

Sunday, 22 March 2020
8:00 AM - 12:00 PM
Lake Anne

STRANGE ATTRACTORS IN LAGERSTATTEN- BUGS ON A STICK AND RAFTING FISH

Paper number: 56-2
Program: Theme Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

Insects, fish, clam shrimp, and other animals are often preserved in monospecific clusters in Konservat Lagerstätten in microlaminated lacustrine sediment. We hypothesize that these clusters are the result of floating algal mats binding these organisms together and eventually sinking with algae degrading without a perceptible trace, leaving anomalous clusters of organisms. Evidence for this phenomenon, difficult to explain other ways, is a anomalous association of insects and a plant from the former Solite quarry, North Carolina-Virginia ([1]) of Early Norian age (Late Triassic) (VMNH 2932). A stick is surrounded by monospecific cluster of many water bugs [Triassonepa solensis: Heteroptera ([2])] of various stages instars decreasing in abundance away from the stick, to which they seem so strangely attracted. The common observation of dead insects in modern floating algal mats parsimoniously suggests that the Triassic bugs were not attracted to the stick, they were bound to it by a now invisible web of filamentous algae. Otherwise, how could these insects retain their relationship with the stick drifting down though tens or even hundreds of meters of water? Clusters of a few to many other insects occur in the same strata, and in some cases the insects are oriented with their long axes in the same direction. Similar clusters occur in other lacustrine Lagerstatten in microlaminated units, notably the Eocene Green River Formation. The oriented insects recall the recent description of what was previously interpreted as fossilized shoaling Green River fish ([3]) that is more simply explained as fish oriented by gentle wave action in a floating algal mat, that subsequently sunk.

([1]) Olsen PE et al. (2018) 20th EGU General Assembly, EGU2018, Proceedings from the conference held 4-13 April, Vienna, Austria, p.11440

([2]) Criscione J & Grimaldi D (2017) Journal of Paleontology, 91(6):1166–1177

([3]) Mizumoto N et al. (2019) Proceedings of the Royal Society B, 268(103):1471-2954

Geological Society of America Abstracts with Programs. Vol. 52, No. 2

doi: 10.1130/abs/2020SE-345463

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