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[dinosaur] Lissamphibian origin and dissorophoid temnospondyls + juvenile Apachesaurus + more



Ben Creisler


Some recent non-dino papers, most with free pdfs:


Free pdf:

Jorge A. HerreraâFlores, Thomas L. Stubbs & Michael J. Benton (2018)
Reply to comments on: Macroevolutionary patterns in Rhynchocephalia: is the tuatara (Sphenodon punctatus) a living fossil?
Palaeontology (advance online publication)
doi: 10.1111/pala.12404

Free pdf:


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Free pdf:

Amphibamiformes (new clade); paper also questions proposed separate stereospondyl origin of caecilians


Rainer R. Schoch (2018)Â
The putative lissamphibian stem-group: phylogeny and evolution of the dissorophoid temnospondyls.
Journal of Paleontology (advance online publication)

Free pdf:



Dissorophoid temnospondyls are widely considered to have given rise to some or all modern amphibians (Lissamphibia), but their ingroup relationships still bear major unresolved questions. An inclusive phylogenetic analysis of dissorophoids gives new insights into the large-scale topology of relationships. Based on a TNT 1.5 analysis (33 taxa, 108 characters), the enigmatic taxon Perryella is found to nest just outside Dissorophoidea (phylogenetic defintion), but shares a range of synapomorphies with this clade. The dissorophoids proper are found to encompass a first dichotomy between the largely paedomorphic Micromelerpetidae and all other taxa (Xerodromes). Within the latter, there is a basal dichotomy between the large, heavily ossified Olsoniformes (Dissorophidae + Trematopidae) and the small salamander-like Amphibamiformes (new taxon), which include four clades: (1) Micropholidae (Tersomius, Pasawioops, Micropholis); (2) Amphibamidae sensu stricto (Doleserpeton, Amphibamus); (3) Branchiosauridae (Branchiosaurus, Apateon, Leptorophus, Schoenfelderpeton); and (4) Lissamphibia. The genera Platyrhinops and Eoscopus are here found to nest at the base of Amphibamiformes. Represented by their basal-most stem-taxa (Triadobatrachus, Karaurus, Eocaecilia), lissamphibians nest with Gerobatrachus rather than Amphibamidae, as repeatedly found by former analyses.


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Free pdf:

Larry F. Rinehart and Spencer G. Lucas (2018)
Description of a juvenile specimen of the Late Triassic amphibian Apachesaurus gregorii: Developmental and relative growth.Â
in Lucas, S.G. and Sullivan, R.M., eds., 2018, Fossil Record 6. New Mexico Museum of Natural History and Science 79: 565-584.Â


We describe a juvenile specimen of Apachesaurus gregorii Hunt, 1993, a terrestriallyadapted metoposaurid amphibian from the Upper Triassic of Arizona, New Mexico and Texas. This important specimen consists of an incomplete skull of 83.9 mm length, incomplete mandibles, shoulder girdle elements, some forelimb bones, and an incomplete vertebral column. Comparisons to adult A. gregorii specimens and to adult and juvenile specimens of other metoposaur species reveal much about the ontogenetic growth and ecology of the species. A preliminary assessment indicates that the Apachesaurus skull grows isometrically, except for the orbits and the posterior width of the cultriform process of the parasphenoid. Depending on location, lateral line canals grow in negative to moderately positive allometry, but never reach the full development seen in other genera. Pleurocentra grow relatively more robust throughout life, and some shape changes in the interclavicle are noted. This pattern of growth differs substantially from that of the other metoposaurids for which comparable data are available and thus is an ontogenetic trajectory distinctive of Apachesaurus. Â


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Free pdf:

HU Zhidan, XIE Tao & YIN Fuguang (2018)
Carbon and oxygen isotopic studies of the horizon of Kueichousaurus Fauna.
Geology in China 45(5): 1039-1048 (in Chinese with English abstract).
DOIï10.12029/gc20180511

Free pdf:


Kueichousaurus fauna is the typical representative of the biological radiation in the latest Triassic marine ecosystem, In order to study the palaeoenvironment of the Kueichousaurus fauna, the authors measured the fine sections in Dingxiao and its adjacent areas of Xingyi, Guizhou Province, and tested the whole rock carbon and oxygen isotope compositions by using the carbonate rock. According to the analytical results, the Î13C values in Nimaigu section range from -6.3 â to 2.6 â, and Î18O values are between -5.7â and -1.2â; the Î13C values in Xiemi section range from-4.5â to 2.5â, and Î18O values are in the range of -5.7â-- --1.2â; the Î13C values of Bawei section range from 0.5 â to 2 â, and Î18O values are between -6.4â and 0.1â; the Î13C values in Dingxiao section range from-4.3â-2.1â, and Î18O values are between-7.3â and 2.5â. According to the correlation analysis of carbon and oxygen isotope data, the isotopic values of Nimaigu, Xiemi and Dingxiao sections were less affected by diagenesis. There are obvious negative Î13C anomalies in the lower part of the horizon of Kueichousaurus fauna in Nimaigu, Xiemi and Dingxiao, closely related to the rapid death of marine organisms in low-water-level periods and the volcanism. Due to the influence of late diagenesis on the Dingxiao section, the seawater paleotemperature in Xingyi area was recovered by using Î18O data of Nimaigu, Xiemi and Dingxiao sections. It is shown that the temperature was between 19 and 27â, with an average about 23â, which indicates a warm climate during that period.

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ALSO may be of interest (but not free):

Tanya M. Smith, Alexandra Houssaye, Ottmar Kullmer, Adeline Le Cabec, Anthony J. Olejniczak, Friedemann Schrenk, John de Vos, Paul Tafforeau
Zachary T. Calamari, Jimmy KuangâHsien Hu & Ophir D. Klein (2018)
Tissue Mechanical Forces and Evolutionary Developmental Changes Act Through Space and Time to Shape Tooth Morphology and Function.
BioEssays (advance online publication)


Efforts from diverse disciplines, including evolutionary studies and biomechanical experiments, have yielded new insights into the genetic, signaling, and mechanical control of tooth formation and functions. Evidence from fossils and nonâmodel organisms has revealed that a common set of genes underlie toothâforming potential of epithelia, and changes in signaling environments subsequently result in specialized dentitions, maintenance of dental stem cells, and other phenotypic adaptations. In addition to chemical signaling, tissue forces generated through epithelial contraction, differential growth, and skeletal constraints act in parallel to shape the tooth throughout development. Here recent advances in understanding dental development from these studies are reviewed and important gaps that can be filled through continued application of evolutionary and biomechanical approaches are discussed.

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Andrea Villa & Massimo Delfino (2018)
Fossil lizards and worm lizards (Reptilia, Squamata) from the Neogene and Quaternary of Europe: an overview.
Swiss Journal of Palaeontology (advance online publication)


Lizards were and still are an important component of the European herpetofauna. The modern European lizard fauna started to set up in the Miocene and a rich fossil record is known from Neogene and Quaternary sites. At least 12 lizard and worm lizard families are represented in the European fossil record of the last 23 Ma. The record comprises more than 3000 occurrences from more than 800 localities, mainly of Miocene and Pleistocene age. By the beginning of the Neogene, a marked faunistic change is detectable compared to the lizard fossil record of Palaeogene Europe. This change is reflected by other squamates as well and might be related to an environmental deterioration occurring roughly at the Oligocene/Miocene boundary. Nevertheless, the diversity was still rather high in the Neogene and started to decrease with the onset of the Quaternary glacial cycles. This led to the current impoverished lizard fauna, with the southward range shrinking of the most thermophilic taxa (e.g., agamids, amphisbaenians) and the local disappearance of other groups (e.g., varanids). Our overview of the known fossil record of European Neogene and Quaternary lizards and worm lizards highlighted a substantial number of either unpublished or poorly known occurrences often referred to wastebasket taxa. A proper study of these and other remains, as well as a better sampling of poorly explored time ranges (e.g., Pliocene, Holocene), is needed and would be of utmost importance to better understand the evolutionary history of these reptiles in Europe.

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