Animals

Permian 300-250mya

Wood Rot Oribatids Springtails Insects Early Beetles Oribatids

The surplus of oxygen allowed amphibians, to take in oxygen through their skins, and arthropods to breathe through a network of branching tubes called tracheae. In an oxygen-rich atmosphere, this opened up evolutionary pathways to enable arthropods to grow to gargantuan proportions. Oxygen would have increased the air pressure, so large flying insects of the time would could get more lift for each beat of their wings. This allowed flying arthropods to reach sizes that are structurally impossible for their present-day relatives.

"Cavities in trunk wood from the Permian...Central Transantarctic Mountains are interpreted to have been produced by oribatid mites (Kellogg and Taylor, 2004). ..
The pattern of attack on the trunk wood was attributable to either mites or the overwintering larvae of coleopterans that fed either directly on the wood or on fungi that was in turn feeding upon the wood in a possible 3-way arthropod–fungal-plant symbiotic relationship . (Slater et al 2012)

"the similarity of fungal-induced cavities in Australoxylon to modern white pocket rot suggests that the fungi's relationship to the host plant was primarily saprotrophic." (Slater et al 2012)

Detrivores

"Detritivores were predominantly oribatid mites, but other larger forms of generalist-and specialist-feeding arthropods are evidenced by the diverse range of coprolites (fossil poo)" (Slater, Mcloughlin, and Hilton, 2015) Check out more about Oribatids in this period

Fungivores

Also in the dead wood mix - check out Springtails

Many arthropods fed on Glossopterids, which were deciduous loosing their leaves in autumn, as plant-root associations with fungi and other microorganisms continued to evolve. There is "the first evidence of endomycorrhizal associations in the seed fern order Glossopteridales based on structurally preserved (permineralised) fossils from the Permian of Antarctica" (Harper et al 2013). This influenced soil ecosystems that enabled the diversification of soil-dwelling arthropods, particularly springtails and mites and other small arachnids, significant in this period..

Overall, the Permian period saw both the continuation and diversification of small soil animals, with several new groups emerging and playing vital roles in the ecosystem. This diversification was crucial for the development of more complex soil structures and nutrient cycles, setting the stage for the ecological changes that would follow in the Mesozoic era.

During the Permian period, some of the small soil animals - particularly springtails and oribatids were already established from previous periods, while others made their first appearances.

Arthropods:

- Millipedes, in particular, were abundant and played significant roles in the decomposition of organic matter.
- Oribatid- mites were particularly important as they contributed to the decomposition and nutrient cycling in soils.
- We see the diversification of several insect groups, that were all to diversify later on - in Mesozoic times.

Annelids: There are no earthworms in the fossil record, although enchytraeids and lung worms were present and contributed to soil aeration and the breakdown of organic material.

Nematodes: were likely abundant in Permian soils, although less so in the drier soils.

Scorpions

Curiously it seems there were more scorpions about in the previous age to this one. The Chemnitz scorpions come from an unequivocally terrestrial palaeoenvironment, significantly without any indication of large standing water bodies, but with multiple lines of evidence (calcic to ferric palaeosols, frequent growth rings in woody plants) for at least seasonally dry conditions. They would find a burrow to stay in and then capture surface creatures like millipedes.

Arthropleura

Some scorpions were found in a petrified Permian Forest, along with other characters we’ve met before, like trigonotarbids, whip scorpions, (Thelyphonida), millipedes (Diplopoda), putative centipedes (Chilopoda) and a giant myriapod Arthropleura. (Dunlop et al 2016) The species of the genus are the largest known land invertebrates of all time, and would have had few, if any, predators. There were no large vertebrate predators at that time. They grew to be 2.5metres long with tracks 50cm wide and most likely ate spores, fruits and seeds, to feed its enormous body. (Schneider et al 2010).

Enigma

‘The enigma of soil animal species diversity'" was the title of a popular article by J. M. Anderson published in 1975. In that paper, Anderson provided insights on the great richness of species found in soils, but emphasized that the mechanisms contributing to the high species richness belowground were largely unknown. Exploration of the mechanisms driving species richness has focused, almost exclusively, on above-ground plant and animal communities

Why soils are so rich in species

Nearly 50 years later we have several new hypotheses but are not much closer to revealing why soils are so rich in species. One persistent but untested hypothesis is that species richness is promoted by small-scale environmental heterogeneity.

To test this hypothesis we manipulated small-scale heterogeneity in soil properties in a one-year field experiment and investigated the impacts on the richness of soil fauna and evenness of the microbial communities. We found that heterogeneity substantially increased the species richness of oribatid mites, collembolans and nematodes, whereas heterogeneity had no direct influence on the evenness of either the fungal, bacterial or archaeal communities or on species richness of the large and mobile Mesostigmatid mites. These results suggest that the heterogeneity-species richness relationship is scale dependent.
Conclusions: Our results provide direct evidence for the hypothesis that small-scale heterogeneity in soils increase species richness of intermediate-sized soil fauna. The concordance of mechanisms between above and belowground communities suggests that the relationship between environmental heterogeneity and species richness may be a general property of ecological communities. There would have been a lot of creatures moving around on the surface of soils, as that surface would now provide a measure of security and stability." (Nielsen et al 2010)

Page updated

Google Sites

Report abuse