The nine-banded armadillo (Dasypus novemcinctus) belongs to the order Xenarthra with geographic distribution wide in the Americas. Xenarthrans are those with greater variation of the number of thoracolumbar vertebrae within the class Mammalia.
The aim of this partial results is to report describe the number of vertebrae of the nine-banded armadillo using radiography, tomography computed (Cl) and gross anatomy to provide data as to the normality.
Twenty nine-banded armadillos were submitted to radiography (DR-F; GE Health Care Unit, Brazil) and CT exams (SCT-7800 TC; Shimadzu, Kyoto, Japan) for the evaluation of the osteoarticular structures of the axial skeleton, four being live animals and sixteen cadavers. Radiographic and CT images were compared with two bony anatomical models of the axial skeleton of the nine-banded armadillo cadavers.
The number of vertebrae obtained for the Dasypus novemcinctus was 7 cervical, which are fused from the second to the forth vertebra in the adult; 10 thoracic, which may be split in cranial thoracic from T1 to T6 and caudal thoracic from T7 to T10 because the latter present prominent mammillary processes; 5 lumbar; 9 vertebrae making up the synsacrum, that include 8 vertebrae with sacral features and one vertebra with caudal features that are fused in the adult; and from 20 to 27 free caudal vertebrae (Figure 1).
Radiographic images on lateral view of the (A) cervical, (B) sacral and (C) thoracolumbar column of an adult nine-banded armadillo showing the vertebrae. C1–7 = cervical; Ca1–3 = caudal vertebrae; L1–5 = Lumbar vertebrae; Synsacrum = fused sacral vertebrae; T1–10 = thoracic vertebrae.
The vertebral formula of the nine-banded armadillos obtained in the present study was C7T10L5S9Ca20-27 and there was no complexity in the execution of the radiographic and CT examinations in these animals.