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Entobia, a sponge boring commonly consisting of interconnected chambers and galleries (i.e., it is camerate), is a dominant agent of bioerosion in Mesozoic and Cenozoic marine carbonates. A similar camerate boring, Topsentopsis devonica, is widely recognized from the Devonian, and its classification is reappraised here. This paper synonymizes Topsentopsis with the senior synonym Entobia, making E. devonica n. comb. the oldest representative of the ichnogenus. New specimens of E. devonica borings in stromatoporoids and megalodont bivalves are described from the Frasnian Guilmette Formation of Nevada, which includes breccias of the Alamo Bolide Impact. The borings occur in skeletal substrates both within and above the impact event breccias, demonstrating their existence prior to the impact and their survival of the catastrophic event. The Nevada discovery extends the geographic distribution of the oldest Entobia to include the western and midcontinental United States, western Canada, and eastern Europe. E. devonica was an important bioerosive agent during the Givetian–Frasnian, but it is unknown following the Frasnian–Famennian mass extinction.
The earliest known record of lingulid-coral associations is described from Ashgill tabulate corals preserved on Manitoulin Island, Ontario. Lingulid infestation of tabulate corals and stromatoporoids also is locally abundant in Ashgill and Llandovery limestones on Anticosti Island, Québec, and these preserve the new lingulid species Rowellella? anticostiensis inside the cavities of Trypanites borings. In all examples, lingulids appear to nestle in previously formed Trypanites, likely in a dead host coral or stromatoporoid. In some instances in the Silurian of Anticosti, regeneration of host growth while infested by lingulids is evidenced by a new type of compound trace fossil, Klemmatoica linguliforma new ichnogenus and ichnospecies. Similar endosymbiotic relationships previously observed in Silurian corals from Wales and Sweden suggest that the lingulid association with tabulate corals and stromatoporoids was widespread in early Paleozoic shallow marine settings.
A fossilized social insect nest, Socialites tumulus new ichnogenus and ichnospecies, is described from continental strata of the Upper Cretaceous Kaiparowits Formation in southern Utah. Nine discrete nest structures are preserved along a single bedding plane, within an area of about 25 m2. Fine-grained, ripple-laminated sandstone, interpreted as a fluvial crevasse splay deposit, drapes the nest structures and is thought to have rapidly buried and preserved much of the aboveground architectural morphology of the nest structures. Such social insects as ants and termites are considered as possible tracemakers. Comparison to fossil and modern nests suggests that Socialites tumulus is more similar to nests produced by ants than by termites. This trace fossil preserves rare, tangible evidence of nest construction by social insects during the Late Cretaceous, adding new information on insect diversity and habitat utilization in Mesozoic terrestrial ecosystems. Detailed study of these complex nest structures also aids in paleoenvironmental reconstruction, revealing multiple phases of nest construction, burial, and reestablishment.
Laser and structured light scanners are primary tools for acquiring surface details of body and trace fossils and have been widely used to study vertebrate specimens. Comparison of different scanner types shows their relative advantages and limitations. Regardless of scanning device, the workflow from initial scan to final product involves registration and some editing for archival or research-grade products. Additional steps, including further object editing and optimization, are required to prepare a scan file for web viewing, animation, and three-dimensional (3-D) printing.
The genus Helicoprion (Chondricthyes, Euchondrocephali) is preserved primarily by a continuous spiral root that forms the base for more than 130 teeth. Helicoprion is found globally in Lower Permian marine rocks and at least 100 specimens exist in public collections worldwide. Ten species of the genus are reviewed in the context of new morphometric analyses conducted on dozens of specimens. Helicoprion whorls share a common inner spiral geometry that results in exponential growth of tooth and root dimensions. Novel growth equations permit calculation of whorl diameter, volution number and tooth count from incomplete specimens. The results of meristic and geometric analyses identify taxobases that distinguish three emended species concepts. Differentiation of form is evident among specimens only after the second volution or roughly the 85th tooth. Helicoprion davisii has widely spaced, stout teeth with tall cutting surfaces and is distinguished from H. bessonowi, which has narrow, closely spaced teeth with short cutting surfaces. Helicoprion ergassaminon is an intermediate form, having narrow, closely spaced teeth with tall cutting surfaces. Several large specimens in the study are too dissimilar to place in the new emended species concepts.
Symbiotic associations are a poorly studied aspect of the fossil record, owing largely to the taphonomic biases that inhibit direct observation that two organisms shared an intimate association in life. A symbiosis between an infesting animal and a skeleton-producing host can form a bioclaustration cavity that directly preserves the association and has a high preservation potential. Identification of ancient mutuals and parasites must reject the null hypothesis of commensalism by demonstrating that the symbiosis correlates with a positive or negative change in host fitness as compared to a non-symbiotic relative of the host taxon. Reviews of the Paleozoic record of marine symbionts show that the majority are hosted by colonial animals, especially corals and calcareous sponges. These hosts include structural forms that have moderate to high levels of integration and can support bioclaustrations between clonal units, mitigating the negative effects of symbionts, and perhaps facilitating the symbiosis.
The fossil record is biased toward recording long-lasting, widespread, equilibrated associations. By contrast, parasitisms that are especially negative to the host are expected to be fossilized rarely. The symbiotic associations that form bioclaustrations may also represent an endolithic adaptive strategy in response to biological antagonisms, such as predation and spatial competition. The Late Ordovician rise in symbiotic bioclaustrations joins burrows and borings as trace fossil examples of infaunalization strategies that accompany the Ordovician faunal radiation.
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