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A reduction in body size (Lilliput effect) has been repeatedly proposed for many marine organisms in the aftermath of the Permian–Triassic (PT) mass extinction. Specifically-reduced maximum sizes of benthic marine invertebrates have been... more
A reduction in body size (Lilliput effect) has been repeatedly proposed for many marine organisms in the
aftermath of the Permian–Triassic (PT) mass extinction. Specifically-reduced maximum sizes of benthic marine
invertebrates have been proposed for the entire Early Triassic. This concept was originally based on observations
on Early Triassic gastropods from the western USA basin and the Dolomites (N Italy) and it stimulated
subsequent studies on other taxonomic groups. However, only a few studies have tested the validity of the
Lilliput effect in gastropods to determine whether the paucity of large-sized gastropods is a genuine signal or
the result of a poor fossil record and insufficient sampling. In combination with a review of the literature, we
document numerous new, abundant, large-sized gastropods from the Griesbachian outcrops of Greenland and
from the Smithian–early Spathian interval in the southwestern USA. We show that large-sized (“Gulliver”)
gastropods (i) were present soon after the PT mass extinction, (ii) occurred in various basins, sedimentary facies
and environmental contexts (from shallow to deeper settings), and (iii) belong to diverse higher-rank taxa.
Focusing on thewestern USA basin,we investigate areas fromwhich microgastropod shell-bedswere previously
presented as being typical. However, we show that Gulliver gastropods do occur in the very same areas.
Insufficient sampling effort is probably the main reason for the rarity of reports of large Early Triassic gastropods,
which is supported by preliminary rarefaction-based simulations. Finally, it appears that the recently
documented middle to late Smithian climate shifts and the severe end-Smithian extinction of nekto-pelagic
faunas did not reduce maximum shell sizes of gastropods.
aftermath of the Permian–Triassic (PT) mass extinction. Specifically-reduced maximum sizes of benthic marine
invertebrates have been proposed for the entire Early Triassic. This concept was originally based on observations
on Early Triassic gastropods from the western USA basin and the Dolomites (N Italy) and it stimulated
subsequent studies on other taxonomic groups. However, only a few studies have tested the validity of the
Lilliput effect in gastropods to determine whether the paucity of large-sized gastropods is a genuine signal or
the result of a poor fossil record and insufficient sampling. In combination with a review of the literature, we
document numerous new, abundant, large-sized gastropods from the Griesbachian outcrops of Greenland and
from the Smithian–early Spathian interval in the southwestern USA. We show that large-sized (“Gulliver”)
gastropods (i) were present soon after the PT mass extinction, (ii) occurred in various basins, sedimentary facies
and environmental contexts (from shallow to deeper settings), and (iii) belong to diverse higher-rank taxa.
Focusing on thewestern USA basin,we investigate areas fromwhich microgastropod shell-bedswere previously
presented as being typical. However, we show that Gulliver gastropods do occur in the very same areas.
Insufficient sampling effort is probably the main reason for the rarity of reports of large Early Triassic gastropods,
which is supported by preliminary rarefaction-based simulations. Finally, it appears that the recently
documented middle to late Smithian climate shifts and the severe end-Smithian extinction of nekto-pelagic
faunas did not reduce maximum shell sizes of gastropods.