In Depth
Though only described from a single rib, the dinosaur Spicomellus has generated a lot of interest. First is the original assessment that Spicomellus represents a primitive ankylosaur, and if true this would not only help to build a pattern of development of this dinosaur lineage all the way back into the Jurassic, something suspected, but difficult to piece together. The second bit of excitement about the genus is the rib itself, and the fact that four ossified spines are fused to it. Indeed, when the specimen first came to the attention of palaeontologists it was first thought to represent a fake, but CT scanning suggested it was actually genuine.
because the spines are fused to the rib this marks Spicomellus as being different from later ankylosaurs where bony plates and spines are not attached to the actual skeleton but ‘float’ in dermal tissues such as skin and muscle. Why they were fused in Spicomellus, we don’t yet know. They were probably for defence, but also a development that may have reduced the mobility of the animal.
If Spicomellusis does indeed represent a primitive ankylosaur, it would be the first dinosaur of its kind known from the African continent.
Further Reading
- Bizarre dermal armour suggests the first African ankylosaur. - Nature Ecology & Evolution. 5 (12): 1576–1581. - Susannah C. R. Maidment, Sarah J. Strachan, Driss Ouarhache, Torsten M. Scheyer, Emily E. Brown, Vincent Fernandez, Zerina Johanson, Thomas J. Raven & Paul M. Barrett - 2021.
