The spinal cord supports of vertebrae in the crown-group salamanders (Caudata, Urodela).
The development of spinal cord supports (bony thickenings which extend into the vertebral canal of vertebrae) in primitive (Salamandrella keyserlingii) and derived (Lissotriton vulgaris) salamanders were described. The spinal cord supports develop as the protuberances of periostal bone of the neural arches in the anteroproximal part of the septal collagenous fibers which connect a transverse myoseptum with the notochord and spinal cord, in the septal bundle inside the vertebral canal. Spinal cord supports were also found in some teleostean (Salmo salar, Oncorhynchus mykiss) and dipnoan (Protopterus sp.) fishes. The absence of the spinal cord supports in vertebrates with cartilaginous vertebrae (lampreys, chondrichthyan, and chondrostean fishes) corresponds to the fact that the spinal cord supports are bone structures. The absence of the spinal cord supports in frogs correlates with the lack of the well developed septal bundles inside the vertebral canal. The spinal cord supports are, presumably, a synapomorphic character for salamanders which originated independently of those observed in teleostean and dipnoan fishes.
Department of Vertebrate Zoology, Saint Petersburg State University, Faculty of Biology and Soil Sciencies, Universitetskaya nab. 7/9, Saint Petersburg 199034, Russian Federation. skutchas@mail.ru
Pavel P
PP
Skutschas
Nataly V
NV
Baleeva
D000818:Animals; D005075:Biological Evolution; D005399:Fishes / Q000033:anatomy & histology; D007798:Lampreys; D009420:Nervous System; D009672:Notochord; D013116:Spinal Cord / Q000033:anatomy & histology*; D013131:Spine / Q000033:anatomy & histology* / Q000254:growth & development; D014562:Caudata / Q000033:anatomy & histology*