The Cranial Anatomy of Chlamydo‐selachus Anguineus

Allis, Edward Phelps

doi:10.1111/j.1463-6395.1923.tb00161.x

Cited by 97 publications

(110 citation statements)

References 20 publications

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“…The positions of these foramina for the orbitonasal vein are consistent with those described in Egertonodus and other elasmobranchs (e.g., Chlamydoselachus and Notorynchus; Maisey, 2004bMaisey, , 1983Shirai, 1992;Allis, 1923). Allis (1923) described the orbitonasal vein in Chlamydoselachus as originating in the nasal capsule and traversing the ectethmoid cham-ber before entering the orbit via the orbitonasal foramen. The positions of the orbitonasal foramina in Tribodus are consistent with this description.…”

Section: Rostral and Ethmoidal Regionssupporting

confidence: 63%

“…3C, 7A, 11, 13, 14: II). 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).…”

Section: Orbitotemporal Regionmentioning

confidence: 99%

“…The olfactory nerve canal is visible on the interior of the braincase as an elongated furrow on the ventrolateral wall of the ethmoid region ( fig. 14: Allis (1923) and Jarvik (1942) noted three major groups of nerves and blood vessels in the anterior of the orbit in Chlamydoselachus: a set of dorsal and ventral foramina within the orbit, and an additional group of structures that pass superficially, lateral to the ectethmoid process (Maisey, 1983). These include the maxillary artery, the facial vein, and two nerve rami: the maxillary ramus of the trigeminal nerve, and the buccal ramus of the facial nerve (now revised as the buccal ramus of the anterodorsal lateral line nerve; Northcutt and Bemis, 1993).…”

Section: Rostral and Ethmoidal Regionsmentioning

confidence: 99%

“…However, there is also no evidence of an optic pedicel in any other known hybodont. Optic pedicels are known in extant neoselachians (e.g., Chlamydoselachus, Squalus, Allis, 1923;Shirai, 1992;Maisey, 2007;batoids, many squaloids and galeomorphs, Shirai, 1992), as well as extinct chondrichthyans (e.g., ''Cobelodus,'' Cladodoides, Maisey, 2005Maisey, , 2007Tamiobatis, Schaeffer, 1981;Synechodus, Maisey, 1985), extinct osteichthyans (e.g., Ligulalepis, Psarolepis, Basden et al, 2000;Zhu et al, 2001;Maisey, 2007) and placoderms (Young, 1986). Presence of an optic stalk may be primitive for gnathostomes, although this feature is absent in extant osteichthyans and chimaeroids (Maisey, 2005) as well as in some extant neoselachians (e.g., many carcharhinoids and the squalean Isistius; Shirai, 1992).…”

Section: Orbitotemporal Regionmentioning

confidence: 99%

“…As Maisey (1983) concluded to be the case in Egertonodus basanus, it seems unlikely that the profundus nerve passed through the orbitonasal canal, because this canal emerges on the ventral side of the braincase where it appears to enter the olfactory capsule (although according to Maisey, 1983, the possibility of a common foramen for the orbitonasal vein and profundus nerve in Egertonodus could not be ruled out). According to Allis (1923), in Chlamydoselachus the profundus nerve emerges on the dorsal surface of the nasal capsule. The profundus nerve in Tribodus may have exited the orbit from a separate foramen dorsal to the orbitonasal foramen, and emerged from a small opening visible on the dorsal surface of the nasal capsule in AMNH 13958.…”

Section: Rostral and Ethmoidal Regionsmentioning

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: Rostral and Ethmoidal Regionssupporting

confidence: 63%

Section: Orbitotemporal Regionmentioning

confidence: 99%

Section: Rostral and Ethmoidal Regionsmentioning

confidence: 99%

Section: Orbitotemporal Regionmentioning

confidence: 99%

Section: Rostral and Ethmoidal Regionsmentioning

confidence: 99%

See 3 more Smart Citations

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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Anatomy of the feeding apparatus of the nurse shark,Ginglymostoma cirratum

Motta

Wilga

1999

J. Morphol.

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The anatomy of the feeding apparatus of the nurse shark, Ginglymostoma cirratum, was investigated by gross dissection and computer axial tomography. The labial cartilages, jaws, jaw suspension, muscles, and ligaments of the head are described. Palatoquadrate cartilages articulate with the chondrocranium caudally by short, laterally projecting hyomandibulae and rostrally by ethmoorbital articulations. Short orbital processes of the palatoquadrates are joined to the ethmoid region of the chondrocranium by short, thin ethmopalatine ligaments. In addition, various ligaments, muscles, and the integument contribute to the suspension of the jaws. When the mouth is closed and the palatoquadrate retracted, the palatine process of the palatoquadrate is braced against the ventral surface of the nasal capsule and the ascending process of the palatoquadrate is in contact with the rostrodorsal end of the suborbital shelf. When the mandible is depressed and the palatoquadrate protrudes slightly rostroventrally, the palatoquadrate moves away from the chondrocranium. A dual articulation of the quadratomandibular joint restricts lateral movement between the mandible and the palatoquadrate. The vertically oriented preorbitalis muscle spans the gape and is hypothesized to contribute to the generation of powerful crushing forces for its hard prey. The attachment of the preorbitalis to the prominent labial cartilages is also hypothesized to assist in the retraction of the labial cartilages during jaw closure. Separate levator palatoquadrati and spiracularis muscles, which are longitudinally oriented and attach the chondrocranium to the palatoquadrate, are hypothesized to assist in the retraction of the palatoquadrate during the recovery phase of feeding kinematics. Morphological specializations for suction feeding that contribute to large subambient suction pressures include hypertrophied coracohyoideus and coracobranchiales muscles to depress the hyoid and branchial arches, a small oral aperture with well-developed labial cartilages that occlude the gape laterally, and small teeth.

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Observations upon the peripheral distribution of the cranial nerves of certain ganoid fishes (amia Lepidosteus, Polyodon, Scaphirhynchus and Acipenser)

Norris

1925

J of Comparative Neurology

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The Cranial Anatomy of Chlamydo‐selachus Anguineus

Cited by 97 publications

References 20 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

Anatomy of the feeding apparatus of the nurse shark,Ginglymostoma cirratum

Observations upon the peripheral distribution of the cranial nerves of certain ganoid fishes (amia Lepidosteus, Polyodon, Scaphirhynchus and Acipenser)

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