Inner ear morphology of diadectomorphs and seymouriamorphs (Tetrapoda) uncovered by high‐resolution x‐ray microcomputed tomography, and the origin of the amniote crown group

  title={Inner ear morphology of diadectomorphs and seymouriamorphs (Tetrapoda) uncovered by high‐resolution x‐ray microcomputed tomography, and the origin of the amniote crown group},
  author={Jozef Klembara and Miroslav Hain and Marcello Ruta and David S. Berman and Stephanie E. Pierce and Amy C. Henrici},
The origin of amniotes was a key event in vertebrate evolution, enabling tetrapods to break their ties with water and invade terrestrial environments. Two pivotal clades of early tetrapods, the diadectomorphs and the seymouriamorphs, have played an unsurpassed role in debates about the ancestry of amniotes for over a century, but their skeletal morphology has provided conflicting evidence for their affinities. Using high‐resolution X‐ray microcomputed tomography, we reveal the three‐dimensional… 
12 Citations
Braincase and Inner Ear Anatomy of the Late Carboniferous Tetrapod Limnoscelis dynatis (Diadectomorpha) Revealed by High-Resolution X-ray Microcomputed Tomography
In order to investigate the phylogenetic position of L. dynatis, a recently published data matrix, including characters of the braincase, was used and subjected it to maximum parsimony analyses under a variety of character weighting schemes and to a Bayesian analysis.
Neurocranial Anatomy of Seymouria from Richards Spur, Oklahoma
ABSTRACT Seymouriamorphs are a group of Permo-Carboniferous tetrapods with both terrestrial and aquatic members. Since their initial discovery, they have been proposed as phylogenetic intermediates
Neurosensory anatomy of Varanopidae and its implications for early synapsid evolution
Computed tomography data reveal that the neuroanatomy of pelycosaur‐grade synapsids is far more complex than previously anticipated, and reconstructed neurosensory anatomy indicates that varanopids may have a much lower‐frequency hearing range compared to more derivedsynapsids.
A Mississippian (early Carboniferous) tetrapod showing early diversification of the hindlimbs
A new East Kirkton tetrapod with an unusual hindlimb morphology reminiscent of that of several stem- and primitive crown amniotes is named and described, with a unique ilium with two slender and elongate processes and a 5-digit pes with a long, stout metatarsal IV and a greatly elongate digit IV.
Anatomy of the neural endocranium, parasphenoid and stapes of Diadectes absitus (Diadectomorpha) from the early Permian of Germany based on the high‐resolution X‐ray microcomputed tomography
A detailed anatomy of the braincase and stapes of the subadult specimen of Diadectes absitus from early Permian sediments of Germany are described for the first time based on the high‐resolution
Morphology of the temporal skull region in tetrapods: research history, functional explanations, and a new comprehensive classification scheme
  • Pascal AbelI. Werneburg
  • Environmental Science, Biology
    Biological reviews of the Cambridge Philosophical Society
  • 2021
A novel comprehensive classification scheme for the various temporal morphotypes in all Tetrapoda that is independent of phylogeny and previous terminology is introduced that may facilitate morphological comparisons in future studies.
Limb-Bone Development of Seymouriamorphs: Implications for the Evolution of Growth Strategy in Stem Amniotes
Tetrapod life on land was the result of a lengthy process, the final steps of which resulted in full independence of amniotic tetrapods from the aquatic environment. Developmental strategies,
A review of the stem amniote Eldeceeon rolfei from the Viséan of East Kirkton, Scotland
A detailed account of individual skull bones and a revision of key axial and appendicular features are provided, alongside the first complete reconstructions of the skull and lower jaw and a revised reconstruction of the postcranial skeleton of Eldeceeon rolfei.
Skull Sutures and Cranial Mechanics in the Permian Reptile Captorhinus aguti and the Evolution of the Temporal Region in Early Amniotes
The sutures in the dermatocranium of the Permian reptile Captorhinus aguti are described in detail to illustrate bone integrity in an early non-fenestrated amniote skull and it is argued that these “weak” areas are prone for the development of temporal openings and may be treated as the possible precursors for infratemporal and supratemporal fenestrae in early amniotes.


A redescription of Orovenator mayorum (Sauropsida, Diapsida) using high‐resolution μCT, and the consequences for early amniote phylogeny
The earliest known neodiapsid Orovenator mayorum from the lower Permian of Oklahoma is redescribed using high‐resolution μCT, revealing remarkable details of the skull anatomy and prompting questions about relationships among early amniotes.
Cranial Morphology of the Carboniferous-Permian Tetrapod Brachydectes newberryi (Lepospondyli, Lysorophia): New Data from µCT
The morphology of the skull of a partial growth series of the lysorophian Brachydectes newberryi is studied using x-ray micro-computed tomography and reveals similarities between the braincase of BrachydECTes and brachystelechid recumbirostrans, corroborating prior work suggesting a close relationship between these taxa.
A phylogenetic study of major groups of Paleozoic tetrapods based on the occiput and closely associated elements of the skull roof finds that the Anthracosauria and Baphetidae are progressively more distant clades or sister taxa.
Bringing Dicynodonts Back to Life: Paleobiology and Anatomy of a New Emydopoid Genus from the Upper Permian of Mozambique
A new dicynodont (Therapsida, Anomodontia) from northern Mozambique is described and synchrotron radiation based micro-computed tomography (SRµCT) combined with a phylogenetic analysis demonstrates a set of characters shared with Emydopoidea.
The Braincase of Eocaecilia micropodia (Lissamphibia, Gymnophiona) and the Origin of Caecilians
The braincase of E. micropodia was examined via micro-computed tomography and Ancestral character state reconstruction confirms the braincase to be largely representative of the plesiomorphic condition of extant caecilians.
Cranial Anatomy, Ontogeny, and Relationships of the Late Carboniferous Tetrapod Gephyrostegus bohemicus Jaekel, 1902
Cranial morphology of the Late Carboniferous terrestrial tetrapod Gephyrostegus bohemicus from the coal deposits of the Nýřany Basin in the Czech Republic is reviewed and a phylogenetic analysis retrieves Gep hyrostegidae as sister group to Seymouriamorpha, although this wider clade receives low bootstrap support.
The Braincase and Endosseous Labyrinth of Plioplatecarpus peckensis (Mosasauridae, Plioplatecarpinae), With Functional Implications for Locomotor Behavior
Comparison of the sensitivity of the canals in each of the three major axes of rotation suggests Plioplatecarpus peckensis may have been most sensitive to movements in the pitch axis, and a detailed, three dimensional reconstruction of the osseous labyrinth for the first time.
The seymouriamorph tetrapod Utegenia shpinari from the ?Upper Carboniferous–Lower Permian of Kazakhstan. Part II: Postcranial anatomy and relationships
  • J. KlembaraM. Ruta
  • Geography
    Transactions of the Royal Society of Edinburgh: Earth Sciences
  • 2003
ABSTRACT The postcranial skeleton of the seymouriamorph Utegenia shpinari (?Upper Carboniferous–Lower Permian, Kurgalin Formation, Kazakhstan) is redescribed. Features that distinguish it from other
The braincase and middle ear region of Dendrerpeton acadianum (Tetrapoda: Temnospondyli)
The morphology and orientation of the stapes provide strong evidence for the presence of an ear adapted to the perception of airborne sound, with similarities to the extant anuran condition, and the reconstructed braincase shows a high degree of similarity to that of other adequately known temnospondyls.
The cranial anatomy of Discosauricsus Kuhn, a seymouriamorph tetrapod from the Lower Permian of the Boskovice Furrow (Czech Republic)
Comparison of the cranial structures of Discosauriscus with those of Seymouria baylorensis, Seymourouria sanjuanensis, and Seymourias shows that Discosuriscus is not a reptile (an amniote animal), and Ariekanerpeton, Utegenia, Urumquia, kotlassiids, leptorophids and Enosuchus require revision.