Original paper
Skeletal and integumental paleopathologies in †Pycnodontomorpha (Osteichthyes: Actinopterygii)
Capasso, Luigi; Ebert, Martin; Witzmann, Florian
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen Band 313 Heft 1 (2024), p. 39 - 66
63 references
published: Nov 26, 2024
published online: Sep 29, 2024
manuscript accepted: Aug 6, 2024
manuscript received: Jun 28, 2024
ArtNo. ESP155031301002, Price: 29.00 €
Abstract
A large sample of pycnodonts, extinct actinopterygians living from the Late Triassic to the Eocene, are studied with the aim of identifying both skeletal and integumental paleopathological conditions. Traces of pathologies are very rare (involving 35 individuals) and mainly concern the skeleton (31 cases), whereas cases involving the dermal scales are exceptional (four cases). It is demonstrated here that congenital anomalies account for 80.6% of paleopathological bone and scale lesions in pycnodonts. Forms of morphological alterations, focal hypotrophy or atrophy are present in the axial and in the fin skeleton, the pectoral girdle and possibly in the skull. Also five cases of traumatic injuries are documented: a single case of fracture, with clear traces of bone repair (fusiform callus) in the skeleton of a dorsal fin and four cases of fin regeneration after bite, concentrated at the posterior tips of the caudal fin. Finally, the existence of a single case of skeletal trace of a soft tissue tumor (chordoma of the notochord) is confirmed. The rarity of the paleopathological lesions indicates that no pathological condition could have encouraged or accelerated the extinction of the pycnodonts; however, it will be necessary to have a wider case series in order to be able to evaluate whether the traces of disease are randomly distributed along the entire period of existence of the pycnodonts or whether they are concentrated in the last stages of their evolution, before their complete extinction.
Keywords
Anomalies • bite marks • bone fracture • congenital malformations • degenerative disease • dermal scales • fossil fishes • fractures • tumors