Braincase of the Upper Devonian Shark Cladodoides Wildungensis (Chondrichthyes, Elasmobranchii), With Observations on the Braincase in Early Chondrichthyans

Maisey, John G.

doi:10.1206/0003-0090(2005)288<0001:botuds>2.0.co;2

Cited by 77 publications

(187 citation statements)

References 65 publications

(75 reference statements)

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“…Comparison The teeth from the Phu Kradung Formation agree with those of the type species of Hybodus, H. reticulatus Agassiz, 1837, in possessing slender and sharply pointed cusp and cusplets, which are recurved distally and lingually and ornamented by numerous ridges (Maisey 1987). The Thai teeth are therefore attributed to this genus.…”

Section: Systematic Palaeontologymentioning

confidence: 53%

“…The Thai teeth are therefore attributed to this genus. They can, however, be easily separated from those of the type species because they possess a coarser ornamentation attaining the apex of cusp and cusplets (Maisey 1987). They are quite similar to those described from the Bathonian-Callovian Khlong Min Formation in southern Thailand.…”

Section: Systematic Palaeontologymentioning

confidence: 66%

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Shark faunas from the Late Jurassic—Early Cretaceous of northeastern Thailand

Cuny

Liard²,

Deesri

et al. 2013

Paläontol Z

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A revision of the freshwater shark fauna from the Phu Kradung Formation in NE Thailand allows the recognition of a new species of Acrodus, which represents the youngest occurrence of the genus and confirms its displacement in freshwater environments after the Toarcian. The rest of the shark fauna includes teeth of Hybodus sp., aff. Hybodus sp., hybodontid dermal denticles, Jiaodontus sp., Lonchidion sp. A, Lonchidion sp. B, Heteroptychodus cf. H. kokutensis and dorsal fin spines. The presence of Jaiodontus and of unusual hybodontid dermal denticles suggests a Jurassic age for most of the Phu Kradung Formation, whereas the presence of Heteroptychodus suggests an Early Cretaceous age for the top of the Formation. However, the age of the Phu Kradung Formation is still uncertain, with contradictory signals coming from palynology, detrital zircon thermochronology and vertebrate palaeontology. In any case, it appears that this is the oldest occurrence of the genus Heteroptychodus, and suggests a Thai origin for this genus, which may have replaced Acrodus in the Thai freshwater palaeoecosystems. Together with Acrodus, the presence of Lonchidion sp. A suggests some European affinities for the shark fauna from the Phu Kradung Formation.

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Section: Systematic Palaeontologymentioning

confidence: 53%

Section: Systematic Palaeontologymentioning

confidence: 66%

Shark faunas from the Late Jurassic—Early Cretaceous of northeastern Thailand

Cuny

Liard²,

Deesri

et al. 2013

Paläontol Z

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show abstract

“…Resembling a cartilaginous prop with a flat, expanded distal end, the optic pedicel is positioned caudally adjacent to the optic foramen and appears to help support the globe within the orbit. However, in various taxa it is either missing (chimaeroids, the ratfish and relatives) or does not directly contact the eye (Walls, 1942;Maisey, 2005). Reportedly, it may act as a passive-elastic mechanism, returning the eye to its original position within the orbit after retraction by the extraocular muscles (Walls, 1942).…”

Section: Skeletal Elements Of the Ocular Adnexamentioning

confidence: 99%

“…Reportedly, it may act as a passive-elastic mechanism, returning the eye to its original position within the orbit after retraction by the extraocular muscles (Walls, 1942). Whereas among extant taxa it is restricted to chondrichthyans, there is evidence to suggest the presence of the optic pedicel among various other types of fossil "fish," including early osteichthyans (bony fish) and the extinct group Placodermi (Maisey, 2005).…”

Section: Skeletal Elements Of the Ocular Adnexamentioning

confidence: 99%

Skeletal elements in the vertebrate eye and adnexa: Morphological and developmental perspectives

Franz‐Odendaal

Vickaryous

2006

Developmental Dynamics

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Although poorly appreciated, the vertebrate eye and adnexa are relatively common sites for skeletogenesis. In many taxa, the skeleton contributes to internal reinforcement in addition to the external housing of the eye (e.g., the circumorbital bones and eyelids). Eyeball elements such as scleral cartilage and scleral ossicles are present within a broad diversity of vertebrates, albeit not therian mammals, and have been used as important models for the study of condensations and epithelial-mesenchymal interactions. In contrast, other elements invested within the eye or its close surroundings remain largely unexplored. The onset and mode of development of these skeletal elements are often variable (early versus late; involving chondrogenesis, osteogenesis, or both), and most (if not all) of these elements appear to share a common neural crest origin. This review discusses the development and distribution of the skeletal elements within and associated with the developing eye and comments on homology of the elements where these are questionable.

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“…Fossil chondrichthyan braincases recently investigated with the aid of CT scanning now include Cladodoides wildungensis (Maisey, 2005) and symmoriiforms (e.g., ''Cobelodus'': Maisey, 2007). Moreover, the extant shark Notorynchus cepedianus has also been examined using CT scanning (Maisey, 2004b), providing valuable information on the relationship of soft anatomical cranial features to skeletal morphology, as well as a control for interpreting the reliability of CT scanning of fossil taxa.…”

Section: Introductionmentioning

confidence: 99%

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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Braincase of the Upper Devonian Shark Cladodoides Wildungensis (Chondrichthyes, Elasmobranchii), With Observations on the Braincase in Early Chondrichthyans

Cited by 77 publications

References 65 publications

Shark faunas from the Late Jurassic—Early Cretaceous of northeastern Thailand

Shark faunas from the Late Jurassic—Early Cretaceous of northeastern Thailand

Skeletal elements in the vertebrate eye and adnexa: Morphological and developmental perspectives

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

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