Holotomography of a Carboniferous Chimaeroid

Impressive brain imagery of a 300 million year old fish…


“This application of holotomography confirms the rapidly growing possibilities of X-ray synchrotron phase imaging techniques in palaeontology, especially when dealing with the exceptional soft-tissue preservations. It imposes synchrotron radiation as a powerful tool for nondestructive imaging of fossils.”

From Abstract: “Living cartilaginous fishes, or chondrichthyans, include numerous elasmobranch (sharks and rays) species but only few chimaeroid (ratfish) species. The early history of chimaeroids, or holocephalans, and the modalities of their divergence from elasmobranches are much debated. During Carboniferous times, 358–300 million years (Myr) ago, they underwent a remarkable evolutionary radiation, with some odd and poorly understood forms, including the enigmatic iniopterygians that were known until now from poorly informative flattened impressions. Here, we report iniopterygian skulls found preserved in 3 dimensions in _300-Myr-old concretions from Oklahoma and Kansas…”

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Figure 1

Fig. 1. The anatomy of iniopterygians. (A) Reconstruction of Sibyrhynchus denisoni (based on ref. 5, not to scale). (B and C) Part (B) and counterpart (C) of a phosphatic nodule from the Pennsylvanian of Oklahoma (AMNH OKM38) containing the braincase and shoulder girdle of Sibyrhynchus sp. (D–F) Threedimensional reconstruction of the same specimen, obtained from conventional X-ray _CT images, showing the braincase in dorsal (D), ventral (E), and lateral (F) view, with associated teeth. (G–I) Three-dimensional reconstruction of the braincase, shoulder girdle, and pectoral fin elements of a sibyrhynchid iniopterygian from the Pennsylvanian of Kansas (KUNHM 21894), based on SR-_CT images. Braincase in dorsal (G), posterior (H), and ventral views, with articulated shoulder girdles and pectoral fin radials (I). Scale bar, 5 mm; f.IX and f.X, foramina for glossopharyngeus and vagus nerves).

Figure 2

Fig. 2. Braincase anatomy and exceptional brain preservation in a sibyrhynchid iniopterygian from the Pennsylvanian of Kansas. (A and B) articulated skull preserved in a nodule (KUNHM 22060) (see also Fig. S1) in dorsal (A) and anterior (B) view (arrow points forward). (C–Q), three-dimensional reconstructions and putative preserved brain structures of the same specimen, obtained from SR-_CT images (and holotomography for brain details). (C–H), Braincase, teeth, and lower jaw in lateral (C), anterior (D), ventral (E), posterior (F), and dorsal (G) view, showing by transparency the outline of the endocranial cavity and labyrinth (H). (I–K), Selected transverse (I and J), and horizontal (K) SR-_CT (holotomography) slices through the calcite-filled endocranial cavity, showing the probably phosphatized brain at the level of the rhombencephalon (I), hypophysis (J), and roof of the optic tectum and cerebellum (K). (L–N) Reconstruction of the endocranial cavity and otic capsule in dorsal (L andM) and lateral (N) view, showing the putative brain by transparency (Mand N). (O–Q), reconstruction of the putative phosphatized brain in dorsal (O), ventral (P), and lateral (Q) view. (Scale bar, 5mmfor A–N and 1mmfor I—K and O–Q. Asc, anterior semicircular canal; Cer, cerebellum; Ed, endolymphatic duct; Hsc, horizontal semicircular canal; Hyp, hypophysis; Olftr, canals for olfactory tracts; Opch, optic chiasm; Optec, optic tectum; Psc, posterior semicircular canal; II, optic nerve; III?, oculomotorius nerve?; IV?, trochlear nerve?; X?, roots of vagus nerve?).


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Pradel, A., Langer, M., Maisey, J., Geffard-Kuriyama, D., Cloetens, P., Janvier, P., & Tafforeau, P. (2009). Skull and brain of a 300-million-year-old chimaeroid fish revealed by synchrotron holotomography Proceedings of the National Academy of Sciences, 106 (13), 5224-5228 DOI: 10.1073/pnas.0807047106