Braincase and Inner Ear Anatomy of the Late Carboniferous Tetrapod Limnoscelis dynatis (Diadectomorpha) Revealed by High-Resolution X-ray Microcomputed Tomography

Klembara, Jozef; Ruta, Marcello; Hain, Miroslav; Berman, David S.

doi:10.3389/fevo.2021.709766

Cited by 6 publications

(42 citation statements)

References 42 publications

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“…Cochlear recesses have been identified previously in Seymouria and in several diadectomorphs (Klembara et al, 2020, 2021); the lack of an identifiable recess in OMNH 79343 suggests two possibilities. First, there may simply be preservational differences between the specimen described here and that described in Klembara et al (2020; MCZ 1086), such that the ventral portion of the opisthotic is more fully ossified in the latter specimen and thus preserves the cochlear recess where OMNH 79343 does not.…”

Section: Discussionmentioning

confidence: 85%

“…Cochlear recesses have been identified previously in Seymouria and in several diadectomorphs (Klembara et al, 2020(Klembara et al, , 2021; the lack of an identifiable recess in OMNH 79343 suggests two possibilities.…”

Section: Inner Earmentioning

confidence: 88%

“…13). We were unable to locate any examples of a cochlear recess situated at the junction of the lateral and posterior canals in any taxa other than those described by Klembara et al, (2020Klembara et al, ( , 2021; while it is possible that diadectomorphs independently evolved a recess that both housed the cochlea and allowed for the passage of the posterior and lateral canals into the vestibule, no such structure is currently known in any other taxon, and how such a structure would function is Diadectes (Klembara et al, 2020(Klembara et al, , 2021, being more similar in curvature to those seen in the early-diverging synapsid clade…”

Section: E-f8c-d)mentioning

confidence: 89%

“…Varanopidae (Bazzana et al, 2021) and in captorhinids (Bazzana et al, 2022;Klembara et al, 2020). The lack of obvious ampullae of the semicircular canals is a trait shared between Seymouria and Limnoscelis (Klembara et al, 2021), differing from the more prominent ampullae of some temnospondyls (Robinson et al, 2005), varanopids (Bazzana et al, 2021), and captorhinids (Bazzana et al, 2022;Klembara et al, 2020). A canal for the endolymphatic duct has been identified in both Diadectes and Limnoscelis (Klembara et al, 2020(Klembara et al, , 2021, but no canal could be seen in OMNH 79343.…”

Section: E-f8c-d)mentioning

confidence: 99%

“…While endocast data for early amniotes is scarce, significant efforts are being made to describe the neuroanatomy of both stem amniotes and early crown amniotes (Bazzana et al, 2021(Bazzana et al, , 2022Klembara et al, 2020Klembara et al, , 2021, and some tentative conclusions may begin to be drawn. The overall similarity between the brain and inner synapsid lineages of amniotes (Jerison, 1973;Streidter, 2005;Tsuboi et al, 2018).…”

Section: Functional Implicationsmentioning

confidence: 99%

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Neurosensory anatomy and function in Seymouria

Bazzana

Evans

Bevitt

et al. 2023

Journal of Morphology

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Seymouria is among the best‐known stem amniotes and holds an important phylogenetic position for discussions of amniote evolution. Previous work has focused primarily on the osteology of Seymouria, with recent interest turning to the application of computed tomography (CT) to study the internal features. We utilized neutron CT to reconstruct the first virtual cranial endocast and the first complete otic endocasts of Seymouria, revealing previously unrecognized details of its palaeoneuroanatomy. The brain and inner ear of Seymouria are largely plesiomorphic relative to later‐diverging crown amniotes, showing no indication of increased encephalization or braincase ossification. Our results also clarify the plesiomorphic condition for carotid artery morphology in amniotes, with Seymouria showing a similar condition to basal members of both the synapsid and sauropsid lineages. The reconstructed neuroanatomy also indicates that Seymouria did not possess any particular neuroanatomical specializations, despite the probable presence of an impedance matching hearing system.

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Section: Discussionmentioning

confidence: 85%

Section: Inner Earmentioning

confidence: 88%

Section: E-f8c-d)mentioning

confidence: 89%

Section: E-f8c-d)mentioning

confidence: 99%

Section: Functional Implicationsmentioning

confidence: 99%

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Neurosensory anatomy and function in Seymouria

Bazzana

Evans

Bevitt

et al. 2023

Journal of Morphology

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A comprehensive phylogeny and revised taxonomy of Diadectomorpha with a discussion on the origin of tetrapod herbivory

Ponstein,

MacDougall,

Fröbisch

2024

R. Soc. Open Sci.

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Among terrestrial tetrapods, the origin of herbivory marked a key evolutionary event that allowed for the evolution of modern terrestrial ecosystems. A 100 Ma gap separates the oldest terrestrial tetrapods and the first undisputed herbivorous tetrapods. While four clades of early tetrapod herbivores are undisputed amniotes, the phylogenetic position of Diadectomorpha with respect to Amniota has long been controversial. Given that the origin of herbivory coincides with the oldest amniotes, and obligate herbivory is unknown within amphibians, this suggests that a key adaptation necessary to evolve obligate herbivory is unique to amniotes. Historically, phylogenetic analyses have found Diadectomorpha as the sister-group to amniotes, but recent analyses recover Diadectomorpha as sister-group to Synapsida, within Amniota. We tested whether diadectomorphs are amniotes by updating the most recent character–taxon matrix. Specifically, we added new characters from the lower jaw and added diadectomorph taxa, resulting in a dataset of 341 characters and 61 operational taxonomic units. We updated the description of five diadectomorph jaws using microcomputed tomography data. Our majority-rule consensus places Diadectomorpha as sister-group to Synapsida; other methods do not recover this relationship. We revise diadectomorph taxonomy, erecting a new species from the early Permian Bromacker locality, Germany, and a new genus to accommodate ‘ Diadectes’ sanmiguelensis .

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The origin of Amniota in phylogenetic context

Marjanović

2024

Preprint

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The membership, phylogeny and external relationships of Amniota quickly achieved “textbook wisdom” status in the mid-1990s, but were all called into question by phylogenetic analyses in the last few years. However, all these analyses and all their predecessors have either focused on early limbed vertebrates and barely extended into Amniota, or focused on amniotes and included very few non-amniotes as outgroups. Here I take an analysis of the first type, perform corrections and updates, and enlarge its sample of amniotes and amniote-related characters (among other things) in order to test these matters. Despite its very high rates of homoplasy, my matrix supports all “microsaurs” as amphibians, perhaps even less close to Amniota than Seymouriamorpha. For Diadectomorpha its “classical” position on the stem of Pan-Amniota is weakly supported; this stem has, however, greatly expanded to include many supposed amniotes, among others the fish-scaled Brouffia. The recent finding of Petrolacosaurus outside Diapsida, indeed outside Amniota along with Captorhinidae, is—weakly—corroborated despite my quite different taxon and character samples. Caseasauria, normally considered part of Pan-Mammalia, is instead nested among the “parareptiles” within Sauropsida; Varanopidae, similarly traditionally placed among the pan-mammals, instead emerges in three separate sauropsid positions. A period of very small body size around the origin of the amniotic egg is not supported by the optimal trees, but trees that seem compatible with it are nearly optimal. Slightly worse trees allow for aïstopods as limbless anthracosaurs. The generally low support for the trees highlights specific needs for future research. Still, it appears that the recently proposed membership of many traditional “microsaurs” in Amniota can be excluded with reasonable confidence, as can a position of Anthracosauria crownward of Temnospondyli or a temnospondyl origin for any extant amphibians. Coding the temporal bone of “microsaurs” and other taxa as the tabular or the supratemporal has practically no effect.

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Braincase and Inner Ear Anatomy of the Late Carboniferous Tetrapod Limnoscelis dynatis (Diadectomorpha) Revealed by High-Resolution X-ray Microcomputed Tomography

Cited by 6 publications

References 42 publications

Neurosensory anatomy and function in Seymouria

Neurosensory anatomy and function in Seymouria

A comprehensive phylogeny and revised taxonomy of Diadectomorpha with a discussion on the origin of tetrapod herbivory

The origin of Amniota in phylogenetic context

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