Compromised bilaterality in the small African pangolin (Phataginus tricuspis) – An expression of or compensation for developmental errors; asymmetry, elliptical Fourier analyses and modularity

ABSTRACT

We present a postnatal evaluation of skull developmental signaling in small African pangolin emphasizing structural, and cognitive trend in ontogeny for assessment of developmental instability, proper identification and classification, forty digitally processed skulls and foramen magnum from different geo-locations were assessed for asymmetry, foramen magnum shape and modularity using geometric and Elliptical Fourier analyses. Multivariate analysis of regression demonstrated low (p < 0.5) but directional fluctuating asymmetry (F₁₅₃₉ = 3.4045, F₈₈₂ = 3.2665, dorsal and ventral views). Allometric trajectories followed rostrocaudal, caudolateral directions; Intercepts for shape/size predictions were parallel. Mahalanobis distances between centroids (2.42) were significant (p < 0.01). The variance-covariance matrix in ontogeny lies between 0.0017 and 0.56. Foramen magnum outline descriptors by incremental harmonics revealed first 4 effective PCs defined 96.98% of shape properties and 3.02% constituted finerdetails. 74.1% accuracy decline after size factor elimination. Modulation PCA of covariance matrix and asymmetry component was 88.38% and 7.48% (PC1 and 2), respectively, the variance % predicted 10.08%. The studied samples confirmed ‘handedness’ and fluctuating asymmetries. Foramen magnum shape assumed priority over size in ontogeny with profound asymmetry (from the 5th harmonic), suggestive of compensations to lateralization in neural integration modules.

KEYWORDS:

• African small pangolins
• laterality
• cognition
• Foramen magnum
• asymmetry
• skull modularity

Acknowledgments

The authors acknowledge the technical staff and the curators of the skull museums in the Departments of Veterinary Anatomy, Federal University of Agriculture, Makurdi & University of Ibadan, and Department of Anatomy, University of Ilorin, for releasing these fragile bones for our investigations. – The authors declare no conflicts of interest.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Availability of data and materials

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Authors’ contributions

SOM conceptualized, wrote and analyzed the results of this manuscript; IOO donated the specimen used for the study; AA proofread and contributed some of the skull samples from another location.

Competing interests

There are no competing interests.

Ethics approval and consent to participate

Ethical approval for the use of these animals was granted by the Animal Care and Use, Research Ethics Committee (ACUREC), University of Ibadan, Nigeria, ethical code number UIACUREC/17/0023.

Consent for publication

Not applicable.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This research did not receive any grant from funding agencies in the public, commercial, or not-for-profit sectors. The author(s) reported there is no funding associated with the work featured in this article.