The development of the chondrocranium of the spiny dogfish, Acanthias vulgaris (Squalus acanthias). Part I. Neurocranium, mandibular and hyoid arches

El‐Toubi, M. R.

doi:10.1002/jmor.1050840204

Cited by 27 publications

(26 citation statements)

References 13 publications

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“…The optic nerve and artery likely passed through this foramen together, as in many other elasmobranchs (e.g., Chlamydoselachus, Allis, 1923;Cladodoides, Maisey, 2005). The optic foramen marks the boundary between the embryonic orbital and trabecular cartilages in extant elasmobranchs (El-Toubi, 1949). The foramen for the trochlear nerve (IV), which innervates the dorsal oblique eye muscle in gnathostomes, is visible on the interorbital wall near the base of the supraorbital crest, dorsal and anterior to the optic foramen (figs.…”

Section: Orbitotemporal Regionmentioning

confidence: 99%

“…This position for the trochlear foramen (anterodorsal to the optic foramen) also occurs in Egertonodus basanus and other hybodonts, and may be of phylogenetic importance as a shared hybodont feature (Maisey, 2004a). Ontogenetically, the trochlear foramen forms within the embryonic orbital cartilage and is surrounded by it on all sides (El-Toubi, 1949).…”

Section: Orbitotemporal Regionmentioning

confidence: 99%

“…Developmentally, in extant elasmobranchs, the embryonic fenestra prootica (an opening between the orbital cartilage and otic capsules) contains the profundus, trigeminal, and abducens nerves, part of the facial nerve, and the anterior lateral line nerves (Goodrich, 1930;Holmgren, 1940;El-Toubi, 1949;Northcutt and Bemis, 1993). Generally, the prootic foramen in adult gnathostomes contains the ophthalmic rami of the trigeminal and anterodorsal lateral line nerves, the entry of the profundus nerve into the orbit, the buccal ramus of the anterodorsal lateral line nerve, and the maxillary and mandibular branches of the trigeminal nerve (V), whereas the palatine and hyomandibular branches of the facial nerve (VII) and the anteroventral lateral line nerve emerge from the facial foramen (Goodrich, 1930;Northcutt and Bemis, 1993).…”

Section: Orbitotemporal Regionmentioning

confidence: 99%

“…The trabeculae probably also contributed to the ethmopalatine processes in Egertonodus. The dorsal part of the orbit (between the optic foramen and superficial ophthalmic foramina) is typically formed by the orbital cartilage in extant elasmobranchs (El-Toubi, 1949). It contains the trochlear and oculomotor foramina, and its posterior margin is formed by the trigeminofacial foramina (marking the position of the embryonic incisura prooticum).…”

Section: Probable Extent Of Embryonic Cartilage In Tribodus and Egertmentioning

confidence: 99%

“…Dorsal to this, the supraorbital crest (lateral to the dorsal row of superficial ophthalmic foramina) is formed by the supraorbital cartilage in Squalus (ElToubi, 1949). The anterior roof of the braincase is usually formed by that cartilage and by the orbital cartilage (El-Toubi, 1949). The lamina orbitonasalis (lateral to the trabeculae) forms the anterolateral wall of the braincase lateral to the orbitonasal canal, including the antorbital or ectethmoid process (El-Toubi, 1949;De Beer, 1937).…”

Section: Probable Extent Of Embryonic Cartilage In Tribodus and Egertmentioning

confidence: 99%

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Morphology of the Braincase in the Cretaceous Hybodont Shark Tribodus limae (Chondrichthyes: Elasmobranchii), Based on CT Scanning

Lane¹

2010

American Museum Novitates

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The braincase of the Lower Cretaceous hybodont shark Tribodus limae is examined using highresolution CT scanning, and its internal and external morphology is described based on threedimensional digital reconstructions. This study represents the first in-depth examination of a hybodont braincase using CT scanning and digital imaging technology. The braincase of an additional Lower Cretaceous hybodont, Egertonodus basanus, is also digitally reconstructed and compared to Tribodus. A reconstruction of cranial nerves and blood vessels in Tribodus is presented on the basis of preserved foramina. The braincase of Tribodus shares many features with those of Egertonodus and neoselachians, providing further support for the sister-group relationship between hybodonts and extant elasmobranchs. CT scans confirm that in both Tribodus and Egertonodus the glossopharyngeal and vagus canals converge and exit from a common foramen (also found in Chlamydoselachus). In both of the hybodonts examined, the trochlear nerve exits the braincase anterior to the optic nerve, a possible hybodont synapomorphy. Separate foramina for the two rami of the octaval nerve are present in both Tribodus and Egertonodus, and may represent an additional hybodont synapomorphy. Also, both taxa have three separate foramina for the trigeminal, facial, and anterodorsal lateral line nerves, apparently including an individual foramen for the superficial ophthalmic complex. However, the basicranial arterial system in Tribodus differs considerably from that of Egertonodus in that in the former the internal carotid arteries enter the braincase much farther posteriorly and through paired foramina rather than a single median foramen. The median ventral basicranial process in Tribodus is similar in structure and position to median ventral processes seen in some extant neoselachians (e.g., Etmopterus) and in embryonic Torpedo (although in the latter this structure disappears during development), and thus may have had a similar ontogenetic origin.

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Section: Orbitotemporal Regionmentioning

confidence: 99%

Section: Orbitotemporal Regionmentioning

confidence: 99%

Section: Orbitotemporal Regionmentioning

confidence: 99%

Section: Probable Extent Of Embryonic Cartilage In Tribodus and Egertmentioning

confidence: 99%

Section: Probable Extent Of Embryonic Cartilage In Tribodus and Egertmentioning

confidence: 99%

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Morphology of the Braincase in the Cretaceous Hybodont Shark Tribodus limae (Chondrichthyes: Elasmobranchii), Based on CT Scanning

Lane¹

2010

American Museum Novitates

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Embryonic development in the bonnethead (Sphyrna tiburo), a viviparous hammerhead shark

Byrum,

Frazier,

Grubbs

et al. 2023

Developmental Dynamics

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BackgroundThe hammerhead sharks (family Sphyrnidae) are an immediately recognizable group of sharks due to their unique head shape. Though there has long been an interest in hammerhead development, there are currently no explicit staging tables published for any members of the group. The bonnethead Sphyrna tiburo is the smallest member of Sphyrnidae and is abundant in estuarine and nearshore waters in the Gulf of Mexico and Western North Atlantic Ocean. Due to their relative abundance, close proximity to shore, and brief gestation period, it has been possible to collect and document multiple embryonic specimens at progressive stages of development.ResultsWe present the first comprehensive embryonic staging series for the Bonnethead, a viviparous hammerhead shark. Our stage series covers a period of development from stages that match the vertebrate phylotypic period, from Stage 23, through stages of morphological divergence to complete development at birth—Stage 35). Notably, we use a variety of techniques to document crucial stages that lead to their extreme craniofacial diversity, resulting in the formation of one of the most distinctive characters of any shark species, the cephalofoil or hammer‐like head.ConclusionDocumenting the development of hard‐to‐access vertebrates, like this viviparous shark species, offers important information about how new and diverse morphologies arise that otherwise may remain poorly studied. This work will serve as a platform for future comparative developmental research both within sharks and across the phylogeny of vertebrates, underpinning the extreme potential of craniofacial development and morphological diversity in vertebrate animals.

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The development of the chondrocranium of the spiny dogfish, Acanthias vulgaris (Squalus acanthias). Part II: Branchial arches and extravisceral cartilages

El‐Toubi¹

1952

Journal of Morphology

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The first part of this work, dealing with the development of the neurocranium, mandibular and hyoid arches, was published in this journal (El-Toubi, '49). The present paper deals with the development of the branchial arches, as well as the extravisceral cartilages. These structures were studied in serial sections of embryos of Acnnthias vztlgaris from which reconstructions on squared paper were made. Other embryos, equal in length to those sectioned and reconstructed, were stained with methylene blue by van Wijhe's method ( '02) for demonstrating the cartilaginous skeleton. The description given below is the result of studying both the serial sections and the methylene blue preparations. Bramchial archesThe old view concerning the development of the branchial n i~l i e s of Selachii is that they appear as continuous cartilaginous rods which become later on divided into the pharyngohranchial, epibranchial, ceratobranchial and hypobranchial. TTan 7rVijhe ('04) showed that this view is incorrect and that it is built on confusing cartilage with procartilage. He stated that the constituent parts of each arch appear, a s cartilagiii-' P a y t of a thesis appoved for the Degree of Doctor of Philosopliy, TIiiivcrsity of Lolldon. 33

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The development of the chondrocranium of the spiny dogfish, Acanthias vulgaris (Squalus acanthias). Part I. Neurocranium, mandibular and hyoid arches

Cited by 27 publications

References 13 publications

Morphology of the Braincase in the Cretaceous Hybodont Shark Tribodus limae (Chondrichthyes: Elasmobranchii), Based on CT Scanning

Morphology of the Braincase in the Cretaceous Hybodont Shark Tribodus limae (Chondrichthyes: Elasmobranchii), Based on CT Scanning

Embryonic development in the bonnethead (Sphyrna tiburo), a viviparous hammerhead shark

The development of the chondrocranium of the spiny dogfish, Acanthias vulgaris (Squalus acanthias). Part II: Branchial arches and extravisceral cartilages

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