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[dinosaur] Vertebral fusions in long necked plesiosaurs (free pdf)




Ben Creisler
bcreisler@gmail.com


A new paper in open access:


Judyth Sassoon (2019)
Congenital and late onset vertebral fusions in long necked plesiosaurs: The first report of spondylosis deformans in Sauropterygians.
Palaeontologia Electronica 22.1.1A: 1-15Â
doi: https://doi.org/10.26879/913
https://palaeo-electronica.org/content/2019/2376-spinal-fusions-in-plesiosaurs
https://palaeo-electronica.org/content/pdfs/913.pdf


Fossilised osseous pathologies can provide useful information about the lifestyles and habits of extinct vertebrates. The Plesiosauria were a diverse Mesozoic marine reptile clade with a unique body plan, exhibiting variations in head and neck morphology. Palaeopathologies are generally uncommon in plesiosaurs but in this study, pathological spinal fusions were identified in the cervical vertebrae of four long-necked, plesiosauromorph specimens from different stratigraphic horizons. The fusions were of two types: a congenital condition (block vertebrae) and a late onset condition, strongly resembling spondylosis deformans. Spondylosis deformans is a non-inflammatory degeneration of intervertebral discs, characterised by the formation of bony projections across the disc space. The condition is commonly identified in extant, domestic animals and humans, but this is the first report of spondylosis deformans in the Plesiosauria. In domestic animals, especially older dogs, spondylosis causes stiffness and pain. The significance of spinal fusions as causes of neck stiffness in long-necked plesiosaurs is discussed and their debilitating potential considered.


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