The fossil history of pseudoscorpions (Arachnida: Pseudoscorpiones)
Pseudoscorpions, given their resemblance to scorpions, have attracted human attention since the time of Aristotle, although they are much smaller and lack the sting and elongated tail. These arachnids have a long evolutionary history but their origins and phylogenetic affinities are still being...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Pensoft Publishers
2017-08-01
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| Series: | Fossil Record |
| Online Access: | https://www.foss-rec.net/20/215/2017/fr-20-215-2017.pdf |
| Summary: | Pseudoscorpions, given their resemblance to scorpions, have attracted human attention since
the time of Aristotle, although they are much smaller and lack
the sting and elongated tail. These arachnids have a long evolutionary
history but their origins and phylogenetic affinities are still being
debated. Here, we summarise their fossil record based on a comprehensive
review of the literature and data contained in other sources. Pseudoscorpions
are one of the oldest colonisers of the land, with fossils known since the
Middle Devonian (ca. 390 Ma). The only arachnid orders with an older
fossil record are scorpions, harvestmen and acariform mites, plus two extinct
groups. Pseudoscorpions do not fossilise easily, and records from the
Mesozoic and Cenozoic consist almost exclusively of amber inclusions. Most
Mesozoic fossils come from Archingeay and Burmese ambers (Late Cretaceous)
and those from the Cenozoic are primarily from Eocene Baltic amber, although
additional fossils from, for example, Miocene Dominican and Mexican
ambers, are known. Overall, 16 of the 26 families of living pseudoscorpions have been
documented from fossils and 49 currently valid species are recognised in the
literature. Pseudoscorpions represent a case of morphological stasis and even
the Devonian fossils look rather modern. Indeed, most amber fossils are
comparable to Recent groups despite a major gap in the fossil record of
almost 250 Myr. Baltic amber inclusions indicate palaeofauna inhabiting
much warmer climates than today and point to climatic shifts in central
Europe since the Eocene. They also indicate that some groups (e.g. Feaellidae
and Pseudogarypidae) had much wider Eocene distributions. Their
present-day occurrence is relictual and highlights past extinction
events. Faunas from younger tropical amber deposits (e.g. Dominican and Mexican
amber) are comparable to Recent ones. Generally, there is a strong bias in
the amber record towards groups that live under tree bark, whereas those from
litter habitats are underrepresented. We also discuss challenges in
interpreting fossils: their cryptic morphology warranting novel techniques of
morphological reconstruction, the massive gap in the fossil record between
the Palaeozoic and Mesozoic, and problems with the classification of
(historically) old amber material. Finally, we discuss aspects of the
palaeoecology and biology of the fossils compared with the Recent fauna, such
as phoresy. |
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| ISSN: | 2193-0066 2193-0074 |