The Structure and the Development of the Chondrocranium of Varanus.

Shrivastava, R. K.

doi:10.2535/ofaj1936.39.3_55

Cited by 11 publications

(15 citation statements)

References 8 publications

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“…Bellairs (1949) shows the same for Varanus monitor , V. salvator and V. niloticus . My own observations confirm this condition for V. acanthurus and V. niloticus in a similar shape and location (although Shrivastava 1963 did not mention or illustrate it). The bundles of the nervus vomeronasalis (running to the vomeronasal organ) are passing through this ‘cartilaginous network’.…”

Section: Methodsmentioning

confidence: 66%

“…Heloderma also has only small crests, but these are better developed than in the varanids. In the papers by Bellairs (1949 ) and Shrivastava (1963) about the ethmoidal region of Varanus their illustrations show no crests at all, while in Varanus acanthurus very small ones are present (personal observations). In the Serpentes there seems to be no lateral projection at all ( Bellairs et al .…”

Section: Methodsmentioning

confidence: 94%

“…It is of no systematic value because a reduction of the cartilago paraseptalis takes place in various, obviously unrelated forms, as is the case in some iguanians and chameleontids as well as in the varanids. The lack of a cartilago paraseptalis in varanids according to Pratt (1948) is clearly refuted by the works of Bellairs (1949) and Shrivastava (1963) and personal observations.…”

Section: Methodsmentioning

confidence: 98%

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Morphology of the nasal capsule of Heloderma suspectum with comments on the systematic position of helodermatids (Squamata: Helodermatidae)

Bernstein

1999

Acta Zoologica

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Bernstein, P. 1999. Morphology of the nasal capsule of Heloderma suspectum with comments on the systematic position of helodermatids (Squamata: Helodermatidae). Ð Acta Zoologica (Stockholm) 80: 219±230 A serially sectioned embryonic head of Heloderma suspectum formed the basis for a three-dimensional reconstruction of the cartilaginous nasal capsule and its membrane bones. Further, the soft parts of the nasal capsule were analysed microscopically. The embryonic nasal capsule is described and compared to the morphological conditions in other lizards, especially the varanids, which many recent authors believe to be their closest relatives.The results support the close affinities between the helodermatids and the varanids. Both groups have a well developed recessus lateralis in a cartilaginous capsule, entered by the nasal concha. Further, in both groups a fragmentation of the cartilago paraseptalis occurs in a comparable location and form. Heloderma has no double lacrimal duct, in contrast to previous accounts, but the two canaliculi at the origin of the duct fuse noteworthy far ahead (in other squamates they fuse in front of the bulbus oculi). In the varanids the two branches of the lacrimal duct remain separate and open separately.Some unique features of Heloderma are presented as well, above all the presence of a second concha.

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Section: Methodsmentioning

confidence: 66%

Section: Methodsmentioning

confidence: 94%

Section: Methodsmentioning

confidence: 98%

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Morphology of the nasal capsule of Heloderma suspectum with comments on the systematic position of helodermatids (Squamata: Helodermatidae)

Bernstein

1999

Acta Zoologica

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“…Whereas a detailed description of the chondrocranial development in V. bengalensis was presented by Shrivastava (1963Shrivastava ( , 1964a, dermatocranial development and particularly the progress of ossification were hardly mentioned. Our paper primarily aims to present a source of embryological information which might be useful for future studies with a comparable comprehensive anatomical approach (Polachowski and Werneburg, 2013).…”

Section: G Modelmentioning

confidence: 98%

Bony skull development in the Argus monitor (Squamata, Varanidae, Varanus panoptes) with comments on developmental timing and adult anatomy

Werneburg

Polachowski

Hutchinson

2015

Zoology

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“…In most published works, information on slice thickness is not provided. In those where it is, sections range from 10 to 50 μm (Shrivastava, , ; Eyal‐Giladi, ; Visser, ; Skinner, ). Historical sections observed in the Embryological Collection Berlin (around 100 years of age) have a thickness of 10 μm in minimum.…”

Section: Discussionmentioning

confidence: 99%

Chondrification and Character Identification in the Skull Exemplified for the Basicranial Anatomy of Early Squamate Embryos

Yaryhin

Werneburg

2017

J Exp Zool Pt B

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The neurocranium of vertebrates is mainly derived from early cartilaginous anlagen, the so-called chondrocranium, the base of the future skull. Two initial bar-shaped and paired chondrifications flank the notochord, the rostral trabecles and the caudal parachordals. In most reptiles, there is an additional component, the transverse acrochordal, which is placed between trabecles and parachordals. All these elements compose the base of the future chondrocranium. There are several drastically different hypotheses concerning the development and interrelationship of these elements. We reexamined the basicranial development in four squamates and found that all species show very similar conditions of early chondrocranial development. The anterior part of the notochord is not embedded into the basal plate as it was previously reported. It remains free. The medial edges of the parachordals form the lateral walls of the basicranial fenestra. Only the posterior portions of the parachordals fuse and form the basal plate. The space in-between the parachordals is filled with a thin layer of cells, which never chondrify. The anterior tips of the parachordals later fuse with the posterior edge of the acrochordal, which ultimately delimitates, as crista sellaris, the basicranial fenestra anteriorly. We consider the observed processes a common development at least in lizards and review a variety of methodological approaches and differences in data interpretation as reasons for the anatomical differences reported in the literature. Moreover, based on our data we argue that the acrochordal is of mesodermal origin, which coincides with results of fate map experimental studies.

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The Structure and the Development of the Chondrocranium of Varanus.

Cited by 11 publications

References 8 publications

Morphology of the nasal capsule of Heloderma suspectum with comments on the systematic position of helodermatids (Squamata: Helodermatidae)

Morphology of the nasal capsule of Heloderma suspectum with comments on the systematic position of helodermatids (Squamata: Helodermatidae)

Bony skull development in the Argus monitor (Squamata, Varanidae, Varanus panoptes) with comments on developmental timing and adult anatomy

Chondrification and Character Identification in the Skull Exemplified for the Basicranial Anatomy of Early Squamate Embryos

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