Mechanisms of dermal bone repair after predatory attack in the giant stem‐group teleost Leedsichthys problematicus Woodward, 1889a (Pachycormiformes)

Leedsichthys problematicus is a suspension‐feeding member of the Mesozoic clade Pachycormiformes (stem‐group Teleostei), and the largest known ray‐finned fish (Actinopterygii). As in some larger fish, the skeleton is poorly ossified, but the caudal fin (tail) is well‐preserved. Bony calluses have be...

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Bibliographic Details
Published in:Journal of anatomy 2022-08, Vol.241 (2), p.393-406
Main Authors: Johanson, Zerina, Liston, Jeff, Davesne, Donald, Challands, Tom, Meredith Smith, Moya
Format: Article
Language:English
Subjects:
Animal biology
Biodiversity
Bone healing
bone repair
Callus
Collagen
dermal bone
Earth Sciences
Leedsichthys
lepidotrichia
Life Sciences
Mesozoic
Original
Original Paper
osteocytes
Paleontology
Sciences of the Universe
Skeleton
Skin
Stem cells
stem‐teleost
Systematics, Phylogenetics and taxonomy
Vertebrate Zoology
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Summary:Leedsichthys problematicus is a suspension‐feeding member of the Mesozoic clade Pachycormiformes (stem‐group Teleostei), and the largest known ray‐finned fish (Actinopterygii). As in some larger fish, the skeleton is poorly ossified, but the caudal fin (tail) is well‐preserved. Bony calluses have been found here, on the dermal fin rays, and when sectioned, show evidence of bone repair in response to damage. As part of this repair, distinctive tissue changes are observed, including the deposition of woven bone onto broken bone fragments and the surface of the lepidotrichium, after resorption of the edges of these fragments and the lepidotrichial surface itself. Within the woven bone are many clear elongate spaces, consistent with their interpretation as bundles of unmineralized collagen (Sharpey's fibres). These normally provide attachment within dermal bones, and here attach new bone to old, particularly to resorbed surfaces, identified by scalloped reversal lines. Haversian systems are retained in the old bone, from which vasculature initially invaded the callus, hence bringing stem cells committed to forming bone onto the surfaces of the damaged area. These observations provide strong evidence of a vital response through survival of a predatory attack by a large marine reptile, coeval with Leedsichthys in the Jurassic seas. Leedsichthys problematicus Woodward, 1889a is a suspension‐feeding member of the Pachycormiformes (stem‐group Teleostei), and the largest known ray‐finned fish (Actinopterygii). Bony calluses have been found on the dermal fin rays of the tail, and when sectioned, show evidence of bone repair in response to damage, including deposition of woven bone onto resorbed surfaces. These observations provide strong evidence of a vital response through survival of a predatory attack by a large marine reptile, coeval with Leedsichthys in the Jurassic seas.
ISSN:0021-8782
1469-7580
1469-7580
DOI:10.1111/joa.13689