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Presents information on a study which discussed permanent ground deformation in unsaturated and compacted hillside fills under seismic loading conditions in California. Overview of grading standards in Southern California; Observations of seismically induced fill movement; Example of effect of fills on structures.

Biomineralised remains of trilobites provide important insight into the evolutionary history of a diverse, extinct group of arthropods. Their exoskeletons are also ideal for recording malformations, including evidence of post-injury repair. Re-examination of historic collections and the study of new specimens is important for enhancing knowledge on trilobite malformations across this diverse clade. To expand the records of these abnormalities and present explanations for their formation, we document eight malformed trilobite specimens, as well as one carcass, housed within the Commonwealth Palaeontological Collection at Geoscience Australia in Canberra. We present examples of Asthenopsis , Burminresia, Centropleura, Coronocephalus, Dolicholeptus, Galahetes, Papyriaspis , and Xystridura from Cambrian, Ordovician, and Silurian deposits of Australia. Most of the malformed specimens show W-, U-, or L-shaped indentations that reflect injuries from either failed predation or complications during moulting, and a mangled carcass is ascribed to either successful predation or post-mortem scavenging. We also uncover examples of teratologies, such as bifurcated pygidial ribs and pygidial asymmetry, in addition to evidence of abnormal recovery ( i.e ., fusion of thoracic segments) from a traumatic incident., Competing Interests: The authors declare that they have no competing interests., (© 2023 Bicknell et al.)

Injured trilobites present insight into how a completely extinct group of arthropods responded to traumatic experiences, such as failed predation and moulting complications. These specimens are therefore important for more thoroughly understanding the Paleozoic predator-prey systems that involved trilobites. To expand the record of injured trilobites, we present new examples of injured Ogygopsis klotzi and Olenoides serratus from the Campsite Cliff Shale Member of the Burgess Shale Formation (Cambrian, Miaolingian, Wuliuan), Paradoxides ( Paradoxides ) paradoxissimus gracilis from the Jince Formation (Cambrian, Miaolingian, Drumian), Ogygiocarella angustissima from the Llanfawr Mudstones Formation (Middle-Late Ordovician, Darriwilian-Sandbian), and Ogygiocarella debuchii from the Meadowtown Formation, (Middle-Late Ordovician, Darriwilian-Sandbian). We consider the possible origins of these malformations and conclude that most injuries reflect failed predation. Within this framework, possible predators are presented, and we uncover a marked shift in the diversity of animals that targeted trilobites in the Ordovician. We also collate other records of injured Ogygo. klotzi and Ol. serratus, and Ogygi. debuchii , highlighting that these species are targets for further understanding patterns and records of trilobite injuries., Competing Interests: The authors declare there are no competing interests., (©2023 Bicknell et al.)

Abnormal trilobites present insight into how arthropods with fully biomineralised exoskeletons recovered from injuries, genetic malfunctions, and pathologies. Records of abnormal Silurian trilobites in particular show an abundance of specimens with teratologies and a limited record of injuries. Here we expand the record of abnormal Silurian trilobites by presenting seven new abnormal specimens of Odontopleura (Sinespinaspis) markhami from the early Silurian (Llandovery, Telychian) Cotton Formation, New South Wales. We use these specimens to illustrate novel evidence for asymmetric distribution of pleural thoracic spine bases. These abnormal bases likely reflect genetic complications, resulting in morphologies that would unlikely have aided the fitness of abnormal individuals. In considering records of malformed Silurian trilobites more broadly, we propose that the largest trilobites may have been prey at this time. This indicates a possible change in the trophic position of trilobites when compared to Cambrian and Ordovician palaeoecosystems., Competing Interests: The authors declare there are no competing interests., (©2022 Bicknell and Smith.)

Documentation of malformed trilobites has presented invaluable insight into the palaeobiology of a wholly extinct euarthropod group. Although the northern hemisphere record is relatively well documented, examples of abnormal trilobites from Australia are limited. Furthermore, most recorded specimens are from Cambrian-aged rocks. To extend this limited record, we document five new examples of malformed Australian trilobites from the Middle and Late Silurian (Wenlock and Ludlow) deposits of the Yarralumla Formation of the Australian Capital Territory and Yarwood Siltstone Member, Black Bog Shale in New South Wales. We record the first examples of abnormal pygidial and thoracic nodes and present new evidence for bifurcating pygidial ribs. These abnormal features are considered teratological morphologies. The aberrant nodes likely arose through developmental malfunctions, while the bifurcating ribs represent either similar defects, or an injury that developed into a teratological feature. Explanations for the limited record of malformed Australian trilobites and for the decrease in injured trilobites after the end-Ordovician are presented. Further documentation of malformed Australian trilobites from the middle-to-late Paleozoic will undoubtedly paint a more complete picture of how Gondwanan taxa recovered from injuries or unfortunate developmental complications., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)