Shrew has a spine of godly strength

@article{Johnston2013ShrewHA,
  title={Shrew has a spine of godly strength},
  author={Richard Malcolm Johnston},
  journal={Nature},
  year={2013}
}
Thor's hero shrew is only second species found to have interlocking vertebrae. 

References

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The functional and biomechanical modifications of the spine of Scutisorex somereni , the hero shrew: skeletal scaling relationships
TLDR
The vertebral column of Scutisorex somereni (the hero shrew), and its size and morphology, is probably the most modified among the vertebrates, and its spine is four times more robust than that reported for any other vertebrate. Expand
Armed and dangerous: predicting the presence and function of defensive weaponry in mammals
TLDR
This comprehensive review of extreme morphological weaponry in mammals demonstrates that several types of defensive weaponry have evolved directly in response to significantly increased potential predation risk, and explores specific hypotheses regarding the ecological, morphological, and behavioral correlates of different types of weaponry. Expand