Cranial anatomy of the stem salamander Kokartus honorarius (Amphibia: Caudata) from the Middle Jurassic of Kyrgyzstan

Skutschas, Pavel P.; Martin, Thomas

doi:10.1111/j.1096-3642.2010.00663.x

Cited by 51 publications

(64 citation statements)

References 43 publications

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“…Surprisingly, the Late Jurassic salamander from western Liaoning, China, clearly shows nonpedicellate teeth that have a monocuspid crown at maturity. The tooth morphology is unknown for the stem caudate Karaurus and Marmorerpeton (14,32), but a recent study has shown that the Middle Jurassic Kokartus as another stem caudate has indeed monocuspid and nonpedicellate teeth (33). The salamander from western Liaoning, as a basal salamandroid, provides unequivocal evidence showing that primitive crown-group salamanders may have had nonpedicellate and monocuspid teeth as the stem caudate Kokartus.…”

Section: Resultsmentioning

confidence: 91%

Late Jurassic salamandroid from western Liaoning, China

Gao

Shubin

2012

Proc. Natl. Acad. Sci. U.S.A.

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A Jurassic salamander, Beiyanerpeton jianpingensis (gen. et sp. nov.), from a recently found site in western Liaoning Province, China is the earliest known record of Salamandroidea. As a Late Jurassic record of the group, it extends the range of the clade by ~40 Ma. The Late Jurassic taxon is neotenic and represented by exceptionally preserved specimens, including fully articulated cranial and postcranial skeletons and bony gill structures close to the cheek region. The fossil beds, consisting of dark-brown volcanic ash shales of the Upper Jurassic Tiaojishan (Lanqi) Formation (Oxfordian), underlie trachyandesite rocks that have yielded a SHRIMP zircon U-Pb date of 157 ± 3 Ma. The fossiliferous beds are substantially older than the Jehol Group, including the Yixian Formation ( 40 Ar/ 39 Ar dates of 122–129 Ma), but slightly younger than the Middle Jurassic Daohugou horizon ( 40 Ar/ 39 Ar date of 164 ± 4 Ma). The early fossil taxon shares with extant salamandroids derived character states, including: separated nasals lacking a midline contact, angular fused to the prearticular in the lower jaw, and double-headed ribs on the presacral vertebrae. In contrast to extant salamandroids, however, the salamander shows a discrete and tooth-bearing palatine, and unequivocally nonpedicellate and monocuspid marginal teeth in large and presumably mature individuals. The finding provides insights into the evolution of key characters of salamanders, and also provides direct evidence supporting the hypothesis that the split between Cryptobranchoidea and Salamandroidea had taken placed before the Late Jurassic Oxfordian time. In this aspect, both paleontological and molecular data now come to agree.

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Section: Resultsmentioning

confidence: 91%

Late Jurassic salamandroid from western Liaoning, China

Gao

Shubin

2012

Proc. Natl. Acad. Sci. U.S.A.

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“…, Rhamphorhynchus muensteri (histological analysis in [39]), two alligators ( Alligator mississippiensis , histological analysis in [47] and [55] respectively), large theropod dinosaurs ( Albertosaurus , Gorgosaurus and Tyrannosaurus , histological analysis in [36], [6]–[57], and two birds ( Buteo buteo and Struthio camelus ). As non-amniote representatives, a Jurassic salamander ( Kokartus , decribed in [58]), a common European frog ( Rana temporaria ) and Diadectes sp. were sampled.…”

Section: Methodsmentioning

confidence: 99%

Preliminary Analysis of Osteocyte Lacunar Density in Long Bones of Tetrapods: All Measures Are Bigger in Sauropod Dinosaurs

Stein

Werner

2013

PLoS ONE

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Osteocytes harbour much potential for paleobiological studies. Synchrotron radiation and spectroscopic analyses are providing fascinating data on osteocyte density, size and orientation in fossil taxa. However, such studies may be costly and time consuming. Here we describe an uncomplicated and inexpensive method to measure osteocyte lacunar densities in bone thin sections. We report on cell lacunar densities in the long bones of various extant and extinct tetrapods, with a focus on sauropodomorph dinosaurs, and how lacunar densities can help us understand bone formation rates in the iconic sauropod dinosaurs. Ordinary least square and phylogenetic generalized least square regressions suggest that sauropodomorphs have lacunar densities higher than scaled up or comparably sized mammals. We also found normal mammalian-like osteocyte densities for the extinct bovid Myotragus, questioning its crocodilian-like physiology. When accounting for body mass effects and phylogeny, growth rates are a main factor determining the density of the lacunocanalicular network. However, functional aspects most likely play an important role as well. Observed differences in cell strategies between mammals and dinosaurs likely illustrate the convergent nature of fast growing bone tissues in these groups.

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“…Salientians first appear in the fossil record in the Early Triassic (Rage and Roček 1989;Evans and Borsuk-Białynicka 2009), followed by Gymnophionomorpha in the Early Jurassic (Jenkins et al 2007) and by Caudata in the Middle Jurassic (Evans et al 1988;Averianov et al 2008;Skutschas and Martin 2011). Of these earliest lissamphibians, only the morphology is known in any detail.…”

Section: Introductionmentioning

confidence: 97%

“…Another set of biological data, unexploited so far in these taxa, bone histology, can yield valuable information on the growth pattern, gross physiology and ecologic adaptation of early amphibians. Below, we provide the first histological data on one of these clades, the karaurids, known from Central Asia (Karaurus, Kokartus: Averianov et al 2008;Skutschas and Martin 2011), Britain (Marmorerpeton, Salamander A: Evans et al 1988) and Portugal (cf. Marmorerpeton: Evans, personal observation).…”

Section: Introductionmentioning

confidence: 99%

Histological study of karaurids, the oldest known (stem) urodeles

et al. 2014

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Little is known about the initial phases of lissamphibian history (before the Cretaceous), because their fossil record is quite scanty. Only the morphology of the earliest members has been investigated, although other sets of data, from bone microanatomy and histology, are known to yield valuable paleobiological information. In the present study, we provide the first histological and microanatomical data on the oldest known stem-urodeles, the karaurids, from the Middle Jurassic. Three humeri from the Upper Bathonian, Oxfordshire, referred to juvenile or subadult individuals of Marmorerpeton and to an unnamed caudate of undetermined (but obviously non-larval) ontogenetic stage, were sampled in order to shed new light on the habitat and ontogeny of these basal caudates. The great compactness of the three humeri suggests that these salamanders were aquatic. The presence of extensive amounts of calcified cartilage in the humeri greatly strengthens the case for the presence of neoteny in these taxa, a suggestion that had initially been made on the basis of a few morphological characters. This constitutes the oldest known occurrence of neoteny in lissamphibians. Finally, bone histology reveals that the growth of Marmorerpeton and the related unnamed caudate was fairly slow and cyclic, a characteristic of extant lissamphibians.

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Cranial anatomy of the stem salamander Kokartus honorarius (Amphibia: Caudata) from the Middle Jurassic of Kyrgyzstan

Cited by 51 publications

References 43 publications

Late Jurassic salamandroid from western Liaoning, China

Late Jurassic salamandroid from western Liaoning, China

Preliminary Analysis of Osteocyte Lacunar Density in Long Bones of Tetrapods: All Measures Are Bigger in Sauropod Dinosaurs

Histological study of karaurids, the oldest known (stem) urodeles

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