Vision in a Middle Ordovician trilobite eye

Tanaka, Gengo; Schoenemann, Brigitte; Hariri, Khadija El; Ono, Tomohiro; Clarkson, Euan N. K.; Maeda, Haruyoshi

doi:10.1016/j.palaeo.2015.05.013

Cited by 7 publications

(9 citation statements)

References 38 publications

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“…Clarkson ; Schoenemann & Clarkson , ; Tanaka et al . ) due to the calcified lenses of their compound eyes. Although the primarily less‐calcified eyes of other marine arthropods groups including crustaceans can preserve in Konservat‐Lagerstätten, the stratigraphic record of such eyes is patchier (e.g.…”

Section: Discussionmentioning

confidence: 99%

Comparative experimental taphonomy of eight marine arthropods indicates distinct differences in preservation potential

2017

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Global biodiversity patterns in deep time can only be understood fully when the relative preservation potential of each clade is known. The relative preservation potential of marine arthropod clades, a diverse and ecologically important component of modern and past ecosystems, is poorly known. We tackled this issue by carrying out a 205-day long comprehensive, comparative, taphonomic experiment in a laboratory by scoring up to ten taphonomic characters for multiple specimens of seven crustacean and one chelicerate species (two true crabs, one shrimp, one lobster, one hermit crab, one stomatopod, one barnacle and one horseshoe crab). Although the results are preliminary because we used a single experimental setup and algal growth partially hampered observations, some parts of hermit crabs, stomatopods, swimming crabs and barnacles decayed slowly relative to other parts, implying differential preservation potentials within species, largely consistent with the fossil record of these groups. An inferred parasitic isopod, manifested by a bopyriform swelling within a hermit crab carapace, decayed relatively fast.We found limited variation in the decay rate between conspecifics, and we did not observe size-related trends in decay rate. Conversely, substantial differences in the decay rate between species were seen after c. 50 days, with shrimps and stomatopods decaying fastest, suggesting a relatively low preservation potential, whereas the lobster, calico crabs, horseshoe crabs and barnacles showed relatively slow decay rates, suggesting a higher preservation potential. These results are supported by two modern and fossil record-based preservation potential metrics that are significantly correlated to decay rate ranks. Furthermore, we speculate that stemward slippage may not be ubiquitous in marine arthropods. Our results imply that diversity studies of true crabs, lobsters, horseshoe crabs and barnacles are more likely to yield patterns that are closer to their true biodiversity patterns than those for stomatopods, shrimps and hermit crabs.

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Section: Discussionmentioning

confidence: 99%

Comparative experimental taphonomy of eight marine arthropods indicates distinct differences in preservation potential

2017

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“…In particular, the early trilobites of the Cambrian and probably their predecessors were bottom dwellers. The invasion of the pelagic and planktonic realm by trilobites did not begin before the Furongian (upper Cambrian) and only was truly under way in the early Ordovician and later ( McCormick & Fortey, 1998 ; Tortello & Esteban, 2003 ; Schoenemann et al, 2010 ; Tanaka et al, 2015 ), during the Great Ordovician Biodiversity Event.…”

Section: Discussionmentioning

confidence: 99%

Why did the UV-A-induced photoluminescent blue–green glow in trilobite eyes and exoskeletons not cause problems for trilobites?

Schoenemann

Clarkson

Horváth

2015

PeerJ

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The calcitic lenses in the eyes of Palaeozoic trilobites are unique in the animal kingdom, although the use of calcite would have conveyed great advantages for vision in aquatic systems. Calcite lenses are transparent, and due to their high refractive index they would facilitate the focusing of light. In some respects, however, calcite lenses bear evident disadvantages. Birefringence would cause double images at different depths, but this is not a problem for trilobites since the difference in the paths of the ordinary and extraordinary rays is less than the diameter of the receptor cells. Another point, not discussed hitherto, is that calcite fluoresces when illuminated with UV-A. Here we show experimentally that calcite lenses fluoresce, and we discuss why fluorescence does not diminish the optical quality of these lenses and the image formed by them. In the environments in which the trilobites lived, UV-A would not have been a relevant factor, and thus fluorescence would not have disturbed or confused their visual system. We also argue that whatever the reason that calcite was never again used successfully in the visual systems of aquatic arthropods, it was not fluorescence.

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“…2011; Paterson et al 2011), and also for the excellently preserved arthropods of Bundenbach (Lower Devonian, Hunsrück Shale), which could be assigned to waters up to 200 m depth (Rust et al 2016), as well as for eurypterids (Anderson et al 2014; Poschmann et al 2016) and for a variety of trilobites (Fordyce & Cronin 1989, 1993; McCormick & Fortey 1998; Schoenemann et al 2008a, 2010; Schoenemann & Clarkson 2015; Tanaka et al . 2015). Other visual systems in the fossil record, such as those of the Carboniferous shrimps Tealliocaris (Briggs & Clarkson 1985), remain to be investigated.…”

Section: Ancient Eyes In the Fossil Recordmentioning

confidence: 99%

“…Other recent studies have involved the use of the eye parameter to determine the relative depths at which different trilobites lived (McCormick & Fortey 1998; Schoenemann et al 2008a, 2010; Schoenemann & Clarkson 2015; Tanaka et al 2015).…”

Section: Ancient Eyes In the Fossil Recordmentioning

confidence: 99%

Vision in fossilised eyes

Schoenemann

Clarkson

2015

Earth and Environmental Science Transactions of the Royal Socie

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This paper presents a review of recent developments in the study of vision in fossil arthropods, beginning with a discussion of the origin of visual systems. A report of the eyes of Cambrian arthropods from different Lagerstätten, especially the compound and median arthropod eyes from the Chengjiang fauna of China, is given. Reference is made also to compound eyes from the lower Cambrian Emu Bay Shale fauna of Australia and the Sirius Passet fauna of Greenland; also to the three-dimensionally preserved 'Orsten' fauna of Sweden. An understanding of how these eyes functioned is possible by reference to living arthropods and by using physical tools developed by physiologists. The eyes of trilobites (lower Cambrian to Upper Permian) are often very well preserved, and the structure and physiology of their calcite lenses, and the eye as a whole, are summarised here, based upon recent literature. Two main kinds of trilobite eyes have been long known. Firstly, there is the holochroal type, in which the lenses are usually numerous, small and closely packed together; this represents the ancestral kind, first found in lowermost Cambrian trilobites. The second type is the schizochroal eye, in which the lenses are relatively much larger and each is separated from its neighbours. Such eyes are confined to the single suborder Phacopina (Lower Ordovician to Upper Devonian). This visual system has no real equivalents in the animal kingdom. In this present paper, the origin of schizochroal eyes, by paedomorphosis from holochroal precursors, is reviewed, together with subsequent evolutionary transitions in the Early Ordovician. A summary of new work on the structure and mineralogy of phacopid lenses is presented, as is a discussion of the recent discovery of sublensar sensory structures in Devonian phacopids, which has opened up new dimensions in the study of trilobite vision.

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Vision in a Middle Ordovician trilobite eye

Cited by 7 publications

References 38 publications

Comparative experimental taphonomy of eight marine arthropods indicates distinct differences in preservation potential

Comparative experimental taphonomy of eight marine arthropods indicates distinct differences in preservation potential

Why did the UV-A-induced photoluminescent blue–green glow in trilobite eyes and exoskeletons not cause problems for trilobites?

Vision in fossilised eyes

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