Browsing by Author "Roelofs, B"

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    Exceptional preservation of organs in Devonian placoderms from the Gogo lagerstätte
    (American Association for the Advancement of Science, 2022-09-16) Trinajstic, K; Long, JA; Sanchez, S; Boisvert, CA; Snitting, D; Tafforeau, P; Dupret, V; Clement, AM; Currie, PD; Roelofs, B; Bevitt, JJ; Lee, MSY; Ahlberg, PE
    The origin and early diversification of jawed vertebrates involved major changes to skeletal and soft anatomy. Skeletal transformations can be examined directly by studying fossil stem gnathostomes; however, preservation of soft anatomy is rare. We describe the only known example of a three-dimensionally mineralized heart, thick-walled stomach, and bilobed liver from arthrodire placoderms, stem gnathostomes from the Late Devonian Gogo Formation in Western Australia. The application of synchrotron and neutron microtomography to this material shows evidence of a flat S-shaped heart, which is well separated from the liver and other abdominal organs, and the absence of lungs. Arthrodires thus show the earliest phylogenetic evidence for repositioning of the gnathostome heart associated with the evolution of the complex neck region in jawed vertebrates. © 2022 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science.
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    Response to comment on “Exceptional preservation of organs in Devonian placoderms from the Gogo largerstätte”
    (American Association for the Advancement of Science, 2023-05-12) Trinajstic, K; Long, JA; Sanchez, S; Boisvert, CA; Snitting, D; Tafforeau, P; Dupret, V; Clement, AM; Currie, PD; Roelofs, B; Bevitt, JJ; Lee, MSY; Ahlberg, PE
    Jensen et al. (1) question evidence presented of a chambered heart within placoderms, citing its small size and apparently ventral atrium. However, they fail to note the belly-up orientation of the placoderm within one nodule, and the variability of heart morphology within extant taxa. Thus, we remain confident in our interpretation of the mineralized organ as the heart. © 2024 American Association for the Advancement of Science. All rights reserved.