Animal Molecular Breeding, 2016, Vol.6, No.2, 1-6
1
Research Report Open Access
A Review on the Occipital Area Morphology in
Nyctereutes Procyonoides
cancrivora
)– Evidence For Developmental Instability?
Samuel O.M.
1, 2
, Olopade J.O.
1
1 Department of Veterinary Anatomy University of Ibadan, Nigeria
2 Department of Veterinary Anatomy University of Agriculture Makurdi, Nigeria
Corresponding email,
ail.com
Animal molecular Breeding, 2016, Vol.6, No.2 doi:
.06.0002
Received: 22 Jan., 2016
Accepted: 04 Mar., 2016
Published: 28 Mar., 2016
Copyright © 2016
Samuel and Olopade, This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Samuel O.M. and Olopade J.O.,
2016, A Review on The Occipital Area Morphology in Nyctereutes Procyonoides cancrivora)–Evidence For Developmental
Instability?, Animal molecular Breeding, 6(2): 1-6 (doi:
.06.0002
)
Abstract
The occipital bone and the foramen magnum are salient structures of the skull; which have been widely studied in various
species due to variability associated with their morphology and the clinico-paleontological significance of related ‘anomalies’. The
aim of this study was to discuss and review literatures on the development, form and construction of the structures in tropical raccoon
dogs (Nyctereutes procyonoides cancrivora) a species noted as most variably sized. Relevant aspects of predisposition to and
diagnosis of neuro-pathologies related to the occipital area as well as species variations in composite architecture of the bone and
foramen magnum in evolutionary perspectives. This review postulates elements of developmental instability exist with predisposition
to dysmorphologies in the occipital area of this species and suggests that this investigation may be of value in canalization,
ontogenetic variability and population studies and serve as important research data in cranio-facial modeling for species
anthropometry and taxonomic classifications.
Keywords
Developmental anatomy; Developmental instability; Occipital bone; Embryology; Morphology; Nyctereutes
procyonoides cancrivora
1 Introduction
1.1 The occipitum
The evolving biology of skull development in relation to ancestry does constrain the morphotype changes possible
in the occipital bone (Gilbert, 2006) with genetic variants disposition to more or less mutation- thresholds through
modularity (Conlon and Raff, 1999), and may induce various changes through correlated progression on the
foramen magnum (Gilbert, 2006), the ratio of which size increases with skull index though not with shape (Ellis et
al., 2009). Radiations and reintroduction of raccoons into new lands has been observed to impact skull size and
shape negatively compared to fossil forms (Nowak, 1984; Nowicki et al., 2011). The
squama occipitalis
morphology in raccoon dogs has been reported to be trapezoid (Hidaka et al.
,
1997; Hatori et al.
,
2003) in
Japanese raccoon dogs (
Nyctereutes
.
procyonoides
.
Viverrinus
) but more triangular in the species found around
Finland (
N.p
.
Ussuriensis
) and Korea (
Nyctereutes procyonoides Koreensis
) (Kauhala et al.
,
1998), similar to
those found in tropical environments (
N.p cancrivorus
). Buffering effects of developmental constraints on
evolution of new phenotypes such as canalization may be overcome by stress factors in different environment
(Halgrimson et al., 2004).
A dorsal median symmetrical division of the bone by a prominent
crista occipitalis externa
(Jurgelenas et al.
,
2007) forms the median demarcation of two lateral depressions. Epigenetic incident frequencies have been
reported to be increased (Samuel et al., 2015)* independent of sex and side, the
canalis condylaris
varies in
number and location between and within species. There is no consensus among several authors on the construction
of this bone; little information exists on excavations and numerous foramina perforating the external aspect of this
structure, along with bilateral grooves which indents the cerebral surface. The occipital sensory area of the brain
resides in the saucer-like bone (Figuti, 2004). The
Pars basilaris
maintains a constant morphology among the
subspecies (Hatori, 1997; Hidaka, 2003).
