Some recent non-dino tetrapod-related papers, some with free pdfs:
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Pavel P. Skutschas, Veniamin V. Kolchanov & James D. Gardner (2021)
Microanatomy and histology of frontal bones in two species of Albanerpeton sensu lato (Lissamphibia: Albanerpetontidae) from the Upper Cretaceous Oldman Formation in southeastern Alberta, Canada.
Historical Biology (advance online publication)
DOI: 10.1080/08912963.2021.1881084
https://www.tandfonline.com/doi/full/10.1080/08912963.2021.1881084
Albanerpetontids are an extinct clade of salamander-like lissamphibians characterised by features such as fused frontals and sculptured skull roof bones. Here we provide a histological analysis of the fused and sculptured frontals in two Late Cretaceous species of the type genus Albanerpeton sensu lato that differ in body size: moderate-sized âAl.â gracile and larger-sized âAl.â nexuosum. Despite general similarities in microanatomy/histology (no sutural trace remains between left and right frontals; sculpture formed by appositional growth of bone; predominance of parallel-fibred bone; and lack of growth marks, secondary osteons, and Sharpeyâs fibres) and the presence of sub-ventrolateral crest canals (possible albanerpetontid synapomorphy), âAl.â nexuosum differs from âAl.â gracile in exhibiting: a distinct three-layered diploà structure; bone remodelling; a higher degree of vascularisation; and more numerous osteocytic lacunae. We suggest that (1) histological differences between âAl.â gracile and âAl.â nexuosum are related to differences in absolute body sizes and relative development of sculpture and robustness of frontals and (2) the sub-ventrolateral crest canals in albanerpetontids are homologous to the canalis arteriae orbitonasalis in modern anurans. Two features (internal vascularisation and lack of Sharpeyâs fibres) support a recent suggestion that albanerpetontids may have relied entirely on cutaneous respiration.
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Free pdf:
Lukas Weiss, Ivan Manzini & Thomas HassenklÃver (2021)
Olfaction across the water-air interface in anuran amphibians.
Cell and Tissue Research (advance online publication)
doi:
https://doi.org/10.1007/s00441-020-03377-5https://link.springer.com/article/10.1007%2Fs00441-020-03377-5Extant anuran amphibians originate from an evolutionary intersection eventually leading to fully terrestrial tetrapods. In many ways, they have to deal with exposure to both terrestrial and aquatic environments: (i) phylogenetically, as derivatives of the first tetrapod group that conquered the terrestrial environment in evolution; (ii) ontogenetically, with a development that includes aquatic and terrestrial stages connected via metamorphic remodeling; and (iii) individually, with common changes in habitat during the life cycle. Our knowledge about the structural organization and function of the amphibian olfactory system and its relevance still lags behind findings on mammals. It is a formidable challenge to reveal underlying general principles of circuity-related, cellular, and molecular properties that are beneficial for an optimized sense of smell in water and air. Recent findings in structural organization coupled with behavioral observations could help to understand the importance of the sense of smell in this evolutionarily important animal group. We describe the structure of the peripheral olfactory organ, the olfactory bulb, and higher olfactory centers on a tissue, cellular, and molecular levels. Differences and similarities between the olfactory systems of anurans and other vertebrates are reviewed. Special emphasis lies on adaptations that are connected to the distinct demands of olfaction in water and air environment. These particular adaptations are discussed in light of evolutionary trends, ontogenetic development, and ecological demands.
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Free pdf:
Free pdf:
https://anatomypubs.onlinelibrary.wiley.com/doi/pdf/10.1002/dvdy.308Before limbs, or fins, can be patterned and grow they must be initiated. Initiation of the limb first involves designating a portion of lateral plate mesoderm along the flank as the site of the future limb. Following specification, a myriad of cellular and molecular events interact to generate a bud that will grow and form the limb. The past three decades has provided a wealth of understanding on how those events generate the limb bud and how variations in them result in different limb forms. Comparatively, much less attention has been given to the earliest steps of limb formation and what impacts altering the position and initiation of the limb have had on evolution. Here, we first review the processes and pathways involved in these two phases of limb initiation, as determined from amniote model systems. We then broaden our scope to examine how variation in the limb initiation module has contributed to biological diversity in amniotes. Finally, we review what is known about limb initiation in fish and amphibians, and consider what mechanisms are conserved across vertebrates.
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Free pdf:
Pasan C Fernando, Paula M Mabee & Erliang Zeng (2021)
Gene network module changes associated with the vertebrate fin to limb transition.
bioRxiv 2021.01.28.428646 (preprint)
doi:
https://doi.org/10.1101/2021.01.28.428646https://www.biorxiv.org/content/10.1101/2021.01.28.428646v1Evolutionary phenotypic transitions, such as the fin to limb transition in vertebrate evolution, result from changes in associated genes and their interactions, often in response to changing environment. Identifying the associated changes in gene networks is vital to achieve a better understanding of these transitions. Previous experimental studies have been typically limited to manipulating a small number of genes. To expand the number of analyzed genes and hence, biological knowledge, we computationally isolated and compared the gene modules for paired fins (pectoral fin, pelvic fin) of fishes (zebrafish) to those of the paired limbs (forelimb, hindlimb) of mammals (mouse) using quality-enhanced gene networks from zebrafish and mouse. We ranked module genes according to their weighted-degrees and identified the highest-ranking hub genes, which were important for the module stability. Further, we identified genes conserved during the fin to limb transition and investigated the fates of zebrafish-specific and mouse-specific module genes in relation to their involvements in newly emerged or lost anatomical structures during the aquatic to terrestrial vertebrate transition. This paper presents the results of our investigations and demonstrates a general network-based computational workflow to study evolutionary phenotypic transitions involving diverse model organisms and anatomical entities.
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