The Braincase in Paleozoic Symmoriiform and Cladoselachian Sharks

Maisey, John G.

doi:10.1206/0003-0090(2007)307[1:tbipsa]2.0.co;2

Cited by 59 publications

(171 citation statements)

References 69 publications

Supporting

Mentioning

161

Contrasting

Unclassified

Order By: Relevance

“…A reconstruction of the skull and endocast based on highresolution computed tomography (HRCT) (Figs 2h and 4; Supplementary Movies 1 and 2) reveals an unexpected combination of brain features seen in Tungsenia. The short olfactory tracts and the anteriorly extending brain cavity recall the conditions in fossil sharks and placoderms 37,38 ( Supplementary Fig. S9).…”

Section: Systematic Palaeontologymentioning

confidence: 77%

The earliest known stem-tetrapod from the Lower Devonian of China

et al. 2012

View full text Add to dashboard Cite

Recent discoveries of advanced fish-like stem-tetrapods (for example, Panderichthys and Tiktaalik) have greatly improved our knowledge of the fin-to-limb transition. However, a paucity of fossil data from primitive finned tetrapods prevents profound understanding of the acquisition sequence of tetrapod characters. Here we report a new stem-tetrapod (Tungsenia paradoxa gen. et sp. nov.) from the Lower Devonian (Pragian, B409 million years ago) of China, which extends the earliest record of tetrapods by some 10 million years. Sharing many primitive features with stem-lungfishes, the new taxon further fills in the morphological gap between tetrapods and lungfishes. The X-ray tomography study of the skull depicts the plesiomorphic condition of the brain in the tetrapods. The enlargement of the cerebral hemispheres and the possible presence of the pars tuberalis in this stem-tetrapod indicate that some important brain modifications related to terrestrial life had occurred at the beginning of the tetrapod evolution, much earlier than previously thought.

show abstract

Section: Systematic Palaeontologymentioning

confidence: 77%

The earliest known stem-tetrapod from the Lower Devonian of China

et al. 2012

View full text Add to dashboard Cite

show abstract

“…The ethmoid region of Tribodus comprises about one-third of the entire length of the braincase, unlike Egertonodus basanus and Hybodus reticulatus, in which the ethmoid region constitutes only one-quarter of its length (Maisey 1983(Maisey , 1987. Maisey (1983) describes the ethmoid region in Egertonodus as shorter than in most living sharks, but similar in length to that of Tristychius, while in Cobelodus, Tamiobatis, and Xenacanthus, the proportion is even lower (Maisey, 2005(Maisey, , 2007. In the extant shark Notorynchus (Maisey, 2004b), the ethmoid region comprises approximately one-third of the total braincase length, resembling the condition in Tribodus.…”

Section: Rostral and Ethmoidal Regionsmentioning

confidence: 99%

“…Although this specimen ( fig. 3) was mentioned in several later papers, revealing a selection of intriguing morphological details (Maisey, 2004a(Maisey, , 2005(Maisey, , 2007, a complete description of its morphology has not been presented until now. Additional specimens of Tribodus limae neurocrania have since been discovered and are included in the present description (figs.…”

Section: Neurocranium General Featuresmentioning

confidence: 99%

“…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%

See 1 more Smart Citation

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

Lane¹

2010

American Museum Novitates

View full text Add to dashboard Cite

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.

show abstract

“…Zidek (1992) studied new specimens of symmoriid skeletons from the Pennsylvanian Wild Cow Formation of Kinney Quarry, New Mexico and referred them to C. aculeatus. Later, Maisey (2007) revised the morphology of symmoriiform braincases and concluded that the New Mexico specimens could be distinguished from C. aculeatus and should be referred to a different genus.…”

Section: B C Dmentioning

confidence: 99%

Chondrichthyans from the Lower Permian of Mechetlino, South Urals

Ivanov¹

2017

Bull. Geosci.

View full text Add to dashboard Cite

The Braincase in Paleozoic Symmoriiform and Cladoselachian Sharks

Cited by 59 publications

References 69 publications

The earliest known stem-tetrapod from the Lower Devonian of China

The earliest known stem-tetrapod from the Lower Devonian of China

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

Chondrichthyans from the Lower Permian of Mechetlino, South Urals

Contact Info

Product

Resources

About