Biological structures with extreme morphologies are puzzling because they often lack obvious functions and stymie comparisons to homologous or analogous features with more typical shapes. An example of such an extreme morphotype is the uniquely modified vertebral column of the hero shrew
Scutisorex
, which features numerous accessory intervertebral articulations and massively expanded transverse processes. The function of these vertebral structures is unknown, and it is difficult to meaningfully compare them to vertebrae from animals with known behavioural patterns and spinal adaptations. Here, we use trabecular bone architecture of vertebral centra and quantitative external vertebral morphology to elucidate the forces that may act on the spine of
Scutisorex
and that of another large shrew with unmodified vertebrae (
Crocidura goliath
). X-ray micro-computed tomography (µCT) scans of thoracolumbar columns show that
Scutisorex thori
is structurally intermediate between
C. goliath
and
S. somereni
internally and externally, and both
Scutisorex
species exhibit trabecular bone characteristics indicative of higher
in vivo
axial compressive loads than
C. goliath.
Under compressive load,
Scutisorex
vertebral morphology is adapted to largely restrict bending to the sagittal plane (flexion). Although these findings do not solve the mystery of how
Scutisorex
uses its byzantine spine
in vivo
, our work suggests potentially fruitful new avenues of investigation for learning more about the function of this perplexing structure.
Deciphering an extreme morphology: bone microarchitecture of the hero shrew backbone (Soricidae:
Scutisorex
)
