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A re-interpretation of the Eocene anuran Thaumastosaurus based on microCT examination of a 'mummified' specimen.

ABSTRACT: What originally appeared to be only an external cast of an anuran 'mummy' from the Quercy Phosphorites (southwestern France) was described as Rana plicata during the 19th century. Its geographical provenance is only vaguely known; therefore its precise age within the Paleogene was uncertain. The taxon was erected on the basis of the external morphology of the specimen, which includes few diagnostic characters. As a further complication, the name Rana plicata was recently shown to be unavailable at the time of the description, and the name Rana cadurcorum was proposed as a replacement. In order to see whether internal features were fossilized, the fossil was CT scanned. This showed that a large part of the skeleton is preserved. Unexpectedly, the scans revealed that the skull of the mummy is almost identical to that of Thaumastosaurus gezei, another anuran from the late middle or late Eocene of the Quercy Phosphorites. The few observed differences are attributable to intraspecific and ontogenetic variation, and R. cadurcorum is a junior subjective synonym of T. gezei. The mummy is therefore probably from the same time interval as T. gezei. The latter was previously known only by its skull, but the mummy provides important information on the postcranial skeleton. Earlier assessments, based only on the skull, placed Thaumastosaurus close to South American hyloid anurans, but a new phylogenetic analysis including postcranial characters reveals ranoid affinities. This study exemplifies the usefulness of modern imaging technologies that allow non-destructive study of previously inaccessible internal anatomical features.

SUBMITTER: Laloy F

PROVIDER: S-EPMC3783478 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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A re-interpretation of the Eocene anuran Thaumastosaurus based on microCT examination of a 'mummified' specimen.

Laloy Fabien F Rage Jean-Claude JC Evans Susan E SE Boistel Renaud R Lenoir Nicolas N Laurin Michel M

PloS one 20130925 9

What originally appeared to be only an external cast of an anuran 'mummy' from the Quercy Phosphorites (southwestern France) was described as Rana plicata during the 19th century. Its geographical provenance is only vaguely known; therefore its precise age within the Paleogene was uncertain. The taxon was erected on the basis of the external morphology of the specimen, which includes few diagnostic characters. As a further complication, the name Rana plicata was recently shown to be unavailable ...[more]

PMID: 24086389

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Project description:PURPOSE:The purpose of this paper is to validate a rapid and cost-effective ex vivo technique, microCT-based virtual histology, as an alternative to MRI imaging for assessing the therapeutic response in genetically engineered mouse models of cancer. PROCEDURES:All animal procedures were conducted in accordance with the Guidelines for the Care and Use of Laboratory Animals and were approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Texas Health Science Center at San Antonio. MRI imaging was performed on 6-week-old, bortezomib-treated genetically engineered Patched1, p53 mice that recapitulate the characteristics of human medulloblastoma. After MRI scans, the same mice were euthanized to collect brain or spine samples for virtual histology staining followed by microCT scanning. RESULTS:Nine-micrometer resolution ex vivo micro X-ray computed tomography (microCT)-based virtual histology images were qualitatively reflective of high-field live animal images obtained with magnetic resonance imaging (MRI) and histopathology. Cerebellar volumes on microCT-based virtual histology correlated closely with MRI cerebellar volumes (R = 0.998). MRI and microCT-based virtual histology both indicated a significant difference between cerebellar volumes of untreated and treated mice (p = 0.02 and p = 0.04, respectively). The ex vivo microCT method also allowed a 7,430-fold improvement in voxel resolution (voxel volume of 729 ?m³ for 9-?m isometric resolution microCT vs. 5,416,800 ?m³ for 400 × 111 × 122 ?m resolution MRI) at a 28% cost savings ($400 vs. $555 per animal). CONCLUSION:The ex vivo, en bloc technique of microCT-based virtual histology matched MRI in reflecting histopathology. MicroCT-based virtual histology proved to be a more cost-effective technique and less labor-intensive. On the other hand, MRI provides ability to perform in vivo imaging, faster scanning and lower radiation dose by sacrificing the spatial resolution. Thus, both in vivo MRI and ex vivo microCT-based virtual histology are effective means of quantitatively evaluating therapeutic response in preclinical models of cerebellar tumors including the childhood cancer, medulloblastoma.

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A re-interpretation of the Eocene anuran Thaumastosaurus based on microCT examination of a 'mummified' specimen.

Publications

A re-interpretation of the Eocene anuran Thaumastosaurus based on microCT examination of a 'mummified' specimen.

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