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Investigation of a bone lesion in a gorgonopsian (Synapsida) from the Permian of Zambia and periosteal reactions in fossil non-mammalian tetrapods.

Authors
  • Kato, Kyle M1
  • Rega, Elizabeth A2
  • Sidor, Christian A3
  • Huttenlocker, Adam K4
  • 1 Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0371, USA.
  • 2 College of Osteopathic Medicine of the Pacific and the Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766-1854, USA.
  • 3 Department of Biology and Burke Museum, University of Washington, Seattle, WA 98105, USA.
  • 4 Department of Integrative Anatomical Sciences, University of Southern California, Los Angeles, CA 90033, USA.
Type
Published Article
Journal
Philosophical Transactions of The Royal Society B Biological Sciences
Publisher
The Royal Society
Publication Date
Mar 02, 2020
Volume
375
Issue
1793
Pages
20190144–20190144
Identifiers
DOI: 10.1098/rstb.2019.0144
PMID: 31928188
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

While only distantly related to mammals, the anatomy of Permian gorgonopsians has shed light on the functional biology of non-mammalian synapsids and on the origins of iconic 'mammal-like' anatomical traits. However, little is known of gorgonopsian behaviour or physiology, which would aid in reconstructing the paleobiological context in which familiar mammalian features arose. Using multi-modal imaging, we report a discrete osseous lesion in the forelimb of a late Permian-aged gorgonopsian synapsid, recording reactive periosteal bone deposition and providing insights into the origins and diversity of skeletal healing responses in premammalian synapsids. We suggest that the localized lesion on the anterolateral (preaxial) shaft of the left radius represents acute periostitis and, conservatively, most likely developed as a subperiosteal haematoma with subsequent bone deposition and limited internal remodelling. The site records an inner zone of reactive cortical bone forming irregular to radial bony spicules and an outer, denser zone of slowed subperiosteal bone apposition, all of which likely occurred within a single growing season. In surveys of modern reptiles-crocodylians, varanids-such haematomas are rare compared to other documented osteopathologies. The extent and rapidity of the healing response is reminiscent of mammalian and dinosaurian bone pathologies, and may indicate differing behaviour or bone physiology compared to non-dinosaurian reptiles. This report adds to a growing list of putative disease entities recognized in early synapsids and broadens comparative baselines for pathologies and the evolution of bone response to disease in mammalian forebears. This article is part of the theme issue 'Vertebrate palaeophysiology'.

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