Format

Send to

Choose Destination
PeerJ. 2017 Aug 10;5:e3496. doi: 10.7717/peerj.3496. eCollection 2017.

Synchrotron scanning reveals the palaeoneurology of the head-butting Moschops capensis (Therapsida, Dinocephalia).

Author information

1
Evolutionary Institute, School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa.
2
School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, South Africa.
3
Beamline ID19, European Synchrotron Radiation Facility, Grenoble, France.
#
Contributed equally

Abstract

Dinocephalian therapsids are renowned for their massive, pachyostotic and ornamented skulls adapted for head-to-head fighting during intraspecific combat. Synchrotron scanning of the tapinocephalid Moschops capensis reveals, for the first time, numerous anatomical adaptations of the central nervous system related to this combative behaviour. Many neural structures (such as the brain, inner ear and ophthalmic branch of the trigeminal nerve) were completely enclosed and protected by bones, which is unusual for non-mammaliaform therapsids. The nearly complete ossification of the braincase enables precise determination of the brain cavity volume and encephalization quotient, which appears greater than expected for such a large and early herbivore. The practice of head butting is often associated with complex social behaviours and gregariousness in extant species, which are known to influence brain size evolution. Additionally, the plane of the lateral (horizontal) semicircular canal of the bony labyrinth is oriented nearly vertically if the skull is held horizontally, which suggests that the natural position of the head was inclined about 60-65°to the horizontal. This is consistent with the fighting position inferred from osteology, as well as ground-level browsing. Finally, the unusually large parietal tube may have been filled with thick conjunctive tissue to protect the delicate pineal eye from injury sustained during head butting.

KEYWORDS:

Bony labyrinth; Dinocephalia; Endocast; Head butting; Moschops; Trigeminal nerve

Conflict of interest statement

The authors declare there are no competing interests.

Supplemental Content

Full text links

Icon for PeerJ, Inc. Icon for PubMed Central
Loading ...
Support Center