Browsing by Author "Bicknell, Russell D. C."
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Item An enigmatic euchelicerate from the Mississippian (Serpukhovian) and insights into invertebrate preservation in the Bear Gulch Limestone, Montana (American Museum novitates, no. 4008)(American Museum of Natural History., 2024-02-01) Bicknell, Russell D. C.; Kimmig, Julien.; Smith, Patrick M. (Patrick Mark); Scherer, Torsten.The Bear Gulch Limestone houses a diverse, exceptionally preserved marine fauna from the early Carboniferous. A wealth of vertebrate and invertebrate forms has previously been recorded from this deposit, including fish, annelids, and several arthropods. To expand the record of Bear Gulch marine arthropods, a new enigmatic, possibly blind euchelicerate, Titanoprosoma edgecombei, gen. et sp. nov., is described. The new euchelicerate taxon displays a hypertrophied, ovate, and structureless prosoma—a morphology unique among marine euchelicerates. We explore how the large prosoma and lack of ocular structures reflect possible adaptations to an infaunal, burrowing lifestyle. This species represents the fourth euchelicerate genus described from the Bear Gulch Limestone, further highlighting the impressive disparity of marine arthropods preserved in the deposit. The addition of novel invertebrate forms found in previously unknown museum material suggests that the Bear Gulch Limestone likely houses a still undocumented diversity of Carboniferous arthropods.Item Ex vivo three-dimensional reconstruction of Acutiramus : a giant pterygotid sea scorpion (American Museum novitates, no. 4004)(American Museum of Natural History., 2023-11-20) Bicknell, Russell D. C.; Kenny, Katrina; Plotnick, Roy E.Pterygotid eurypterids include some of the largest aquatic arthropods in the fossil record and are known from middle Silurian to Middle Devonian deposits across the globe. These forms primarily preserve as mostly two-dimensional impressions, a situation that has impacted the accurate reconstruction of pterygotid ventral structures and organization. By documenting specimens displaying important dorsal and ventral structures from both Acutiramus—a larger, well-documented pterygotid genus—and other pterygotids, we reconstruct Acutiramus in three-dimensions (3D) to more thoroughly understand the functional morphology and limb arrangement of these large eurypterids. With this comprehensive 3D reconstruction, we demonstrate a much more anterior insertion of appendages II–V, a near-horizontal orientation of appendages II–VI coxae, the presence of reduced appendage II, and a labrum and epistomel region. The labrum and epistomel sections are identified as the locality for cheliceral articulation. This model also uncovers the streamlined nature and low-profile morphology of Acutiramus. We use our model to explore the morphofunctionality of pterygotid eurypterids, including their feeding strategies, addressing a conundrum inherent in previous pterygotid reconstructions.Item Supplemental material for 'Ex vivo three-dimensional reconstruction of Acutiramus : a giant pterygotid sea scorpion (American Museum novitates, no. 4004)'(American Museum of Natural History., 2023-11) Bicknell, Russell D. C.; Kenny, Katrina; Plotnick, Roy E.Supplemental material for 'Ex vivo three-dimensional reconstruction of Acutiramus : a giant pterygotid sea scorpion (American Museum novitates, no. 4004)' - https://hdl.handle.net/2246/7335Item A trilobite cluster from the Silurian Rochester Shale of New York : predation patterns and possible defensive behavior. (American Museum novitates, no. 3937)(American Museum of Natural History., 2019-09-09) Bicknell, Russell D. C.; Paterson, John R.; Hopkins, Melanie J.Evidence of predator-prey interactions in the fossil record offers important insights into extinct ecosystems. As direct predator-prey relationships are rarely preserved, records of failed predation upon prey species are often considered. The biomineralized exoskeleton of trilobites is exemplary for recording injuries that have resulted from predation. Despite the extensive documentation of trilobite injuries, abnormal specimens are often documented in isolation, with examples of injuries among clustered individuals being poorly known. Here we document a well-preserved body cluster of 18 individuals of the large lichid trilobite Arctinurus boltoni from the mid-Silurian (Wenlock) Rochester Shale of New York, with eight specimens showing injuries. Landmark geometric morphometrics of the specimens is used to explore possible patterns between injured and noninjured specimens. Results of the morphometric analysis indicate that injured and noninjured specimens do not show any systematic difference in overall shape of the exoskeleton, but many of the larger specimens have injuries. The majority of injuries are posteriorly located and right-side dominant, highlighting the possibility of predator or prey lateralization. Biostratinomic evidence suggests that the cluster represents a biological aggregation that was rapidly buried in situ. Potential reasons for this gregarious behavior are discussed, including the possibility that individuals of A. boltoni grouped together to provide "safety in numbers" against predatory attack.