[dinosaur] Vinchinavis, new Miocene eagle + tuatara genome + caecilians fossil record + more

Ben Creisler

Recent non-dino papers:

Vinchinavis paka gen. et sp. nov.

Claudia P. Tambussi, Federico J. Degrange, Patricia L. Ciccioli & Francisco Prevosti (2020)
Avian remains from the Toro Negro Formation (Neogene), Central Andes of Argentina.
Journal of South American Earth Sciences 102988
doi: https://doi.org/10.1016/j.jsames.2020.102988
https://www.sciencedirect.com/science/article/abs/pii/S0895981120305319

Highlights

Avian remains from the late Miocene of Northwestern Argentina are described extensively.
A new genus and species of a large eagle is proposed.
Herbivorous rheids, scavengers condors and zoophagous eagles are represented in the Toro Negro Formation at La Rioja Province.
Palaeoenvironmental considerations from the Toro Negro Formation are made.

Abstract

We describe new avian remains from the lower levels of the Toro Negro Formation (~7-6âMa, UâPb), exposed in Quebrada de la Troya between Vinchina and JagÃÃ towns in La Rioja Province, Argentina. The Toro Negro Formation is composed of a thick continental sequence (~2.4âkm) of sandstones, conglomerates and mudstones deposited in both fluvial and lacustrine systems at the base of the unit. The avifauna of Toro Negro is low in diversity, and the majority of the remains are fragmentary and isolated. However, it is interesting in that it includes carnivorous birds such as a new species of a large eagle (Vinchinavis paka gen. et sp. nov.), scavengers (condors) and large herbivores (rheas). On the whole, the occurrences documented within the Toro Negro Formation confirm the presence of taxa with strong temperate warm preferences that typically inhabits open areas with arboreal patches within an arid-semiarid zone. The palaeoenvironmental characteristics of the fauna are confirmed as fully compatible with the evidence previously obtained through sedimentology and facies analysis.

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Ying Xiong & Fumin Lei (2020)
SLC2A12 of SLC2 gene family in bird provides functional compensation for the loss of SLC2A4 gene in other vertebrates.
Molecular Biology and Evolution, msaa286
doi: https://doi.org/10.1093/molbev/msaa286
https://academic.oup.com/mbe/advance-article/doi/10.1093/molbev/msaa286/5952690

Avian genomes are small and lack some genes that are conserved in the genomes of most other vertebrates including non-avian sauropsids. One hypothesis stated that paralogs may provide biochemical or physiological compensation for certain gene losses; however, no functional evidence has been reported to date. By integrating evolutionary analysis, physiological genomics, and experimental gene interference, we clearly demonstrate functional compensation for gene loss. A large-scale phylogenetic analysis of over 1,400 SLC2 gene sequences identifies six new SLC2 genes from non-mammalian vertebrates and divides the SLC2 gene family into four classes. Vertebrates retain class III SLC2 genes but partially lack the more recent duplicates of class I and II. Birds appear to have completely lost the SLC2A4 gene that encodes an important insulin-sensitive GLUT in mammals. We found strong evidence for positive selection, indicating that the N-termini of SLC2A4 and SLC2A12 have undergone diversifying selection in birds and mammals, and there is a significant correlation between SLC2A12 functionality and basal metabolic rates in endotherms. Physiological genomics have uncovered that SLC2A12 _expression_ and allelic variants are associated with insulin sensitivity and blood glucose levels in wild birds. Functional tests have indicated that SLC2A12 abrogation causes hyperglycemia, insulin resistance, and high relative activity, thus increasing energy expenditures that resemble a diabetic phenotype. These analyses suggest that the SLC2A12 gene not only functionally compensates insulin response for SLC2A4 loss, but it also affects daily physical behavior and basal metabolic rate during bird evolution, highlighting that older genes retain a higher level of functional diversification.

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S.K. Lamar, N.J. Gemmell & N.J. Nelson (2020)
Genome sequencing of an archaic reptile both answers and asks questions
Zoology 125862
doi: https://doi.org/10.1016/j.zool.2020.125862
https://www.sciencedirect.com/science/article/abs/pii/S0944200620301215

Highlights

The tuatara genome was recently sequenced, revealing many characteristics unique to this basal amniote.
Genes related to the specialized thermosensing requirements and temperature dependent sex determination of tuatara were found.
An improved understanding of the mechanisms behind tuatara thermal ecology opens the door to concise management strategies in a warming world.

Abstract

Tuatara (Sphenodon punctatus) are the sole surviving members of the order Rhynchocephalia and offer insight into the evolution of basal amniotes. Recent work sequencing the genome of tuatara revealed characteristics that emphasize the uniqueness of this species, many of which are linked to their thermal ecology. Genes related to their extremely low optimal body temperature and unique form of temperature-dependent sex determination were identified. Further, sequencing highlights the uniqueness of the heavily debated species of North Brother Island tuatara. These results not only inform our understanding of amniote evolution, but also serve as vital background for new and creative research.

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Rodolfo OtÃvio Santos, Michel Laurin & Hussam Zaher (2020)
A review of the fossil record of caecilians (Lissamphibia: Gymnophionomorpha) with comments on its use to calibrate molecular timetrees.
Biological Journal of the Linnean Society, blaa148 (advance online publication)
doi: https://doi.org/10.1093/biolinnean/blaa148
https://academic.oup.com/biolinnean/advance-article-abstract/doi/10.1093/biolinnean/blaa148/5952892

Gymnophiona, popularly known as caecilians, the most poorly known major taxon of extant amphibians, are elongate and limbless tetrapods, with compact ossified skulls and reduced eyes, mainly adapted to fossorial life as adults. Caecilians are poorly represented in the fossil record, but despite the scarcity of fossil specimens described (only four named taxa, in addition to indeterminate fragmentary material), their fossils play a key role in our knowledge of the origin and evolution of Lissamphibia, as well as contribute directly to a better understanding of the phylogeny, taxonomy and biogeography of extant gymnophionan taxa. These records are scattered throughout geological time (from the Jurassic to the sub-Recent) and space (North and South America and Africa). Here, we revisit the caecilian fossil record, providing a brief description of all known extinct taxa described so far, along with general remarks about their impact on systematics, time range, and geographical distribution of the clade, as well as prospects for future research. Possible calibration constraints based on the caecilian fossil record are provided.

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Tamara G. PetroviÄ, Tanja VukovNataÅa & TomaÅeviÄ Kolarov (2020)
Patterns of correlations and locomotor specialization in anuran limbs: association with phylogeny and ecology.
Zoology 125864
doi: https://doi.org/10.1016/j.zool.2020.125864
https://www.sciencedirect.com/science/article/abs/pii/S0944200620301239

Highlights

Anurans showed shared patterns of functionally based morphological integration.
Higher correlations in elements within limbs then between limbs were observed.
Strongest correlations were between humerus-radioulna and femur-tibiofibula.
The changes of correlation patterns are shown to be dissociated from phylogeny.
The species with similar locomotor behavior displayed similar integration patterns.

Abstract

As anuran saltatory locomotion has specific functional requirements achieved through certain intra- and inter-limb proportions, we analyzed pattern and degree of morphological integration in limbs of ten anuran species to reveal the relationship of shared developmental programs of serially homologous structures and locomotor specialization. Our main objectives were (1) to examine if morphological and functional differences in forelimb and hindlimb were associated with reduced covariation between limbs, (2) and to reveal patterns of correlation between species and the roles played by evolutionary history (phylogeny) and ecology (lifestyle and habitat use). Species with different locomotor behaviours (walking, jumping, hopping, running, climbing, swimming and burrowing) were used. Partial correlations showed that species shared similar patterns of functionally based morphological integration, with increased correlations in elements within limbs and reduced correlations between limbs. This was mainly based on strong correlations between proximal elements, humerus-radioulna and femur-tibiofibula. To test the influence of phylogenetic relationships and ecological demands we used different matrices (correlation similarity matrix, ecological similarity matrix, matrices of phylogenetic distance and morphological distance). The changes in correlation patterns are shown to be dissociated from phylogeny. On the other hand, they are to some extent shaped by habitat use and locomotion, as the species with similar locomotor behaviour also tend to have stronger similarity in integration patterns. The results from this study provide insight into the processes underlying the evolutionary change of anuran limbs, highlighting function as the main factor that shaped morphological integration of the examined species.

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Fernando Rodriguez-Rojas, Oscar Borrero-Lopez, Paul J. Constantino, Amanda G. Henry and Brian R. Lawn (2020)
Phytoliths can cause tooth wear. Â
Journal of The Royal Society Interface 17(172): 1720200613
doi: http://doi.org/10.1098/rsif.2020.0613
https://royalsocietypublishing.org/doi/10.1098/rsif.2020.0613

Free pdf:

https://royalsocietypublishing.org/doi/pdf/10.1098/rsif.2020.0613

Comparative laboratory sliding wear tests on extracted human molar teeth in artificial saliva with third-body particulates demonstrate that phytoliths can be as effective as silica grit in the abrasion of enamel. A pin-on-disc wear testing configuration is employed, with an extracted molar cusp as a pin on a hard disc antagonist, under loading conditions representative of normal chewing forces. Concentrations and sizes of phytoliths in the wear test media match those of silica particles. Cusp geometries and ensuing abrasion volumes are measured by digital profilometry. The wear data are considered in relation to a debate by evolutionary biologists concerning the relative capacities of intrinsic mineral bodies within plant tissue and exogenous grit in the atmosphere to act as agents of tooth wear in various animal species.

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P. Tassy & M. S. Fischer Â(2020)
"Cladus" and clade: a taxonomic odyssey.
Theory in Biosciences (2020)Cite this article
doi: https://doi.org/10.1007/s12064-020-00326-2
https://link.springer.com/article/10.1007/s12064-020-00326-2

The fate of "clade," both as concept and word, is reconstructed here beginning with its first appearance in 1866 as "Cladus," in Haeckelâs Generelle Morphologie, continuing up to the present. Although central to phylogenetics, the concept of clade is paradoxical since it has been ambiguously understood or even misunderstood by its own promoters. Writings by Ernst Haeckel, Lucien CuÃnot, and Julian Huxley, the three authors who discussed the notion of clade at length, are analyzed here in detail as a means of exploring this paradox. First conceived as a rank for a higher-level category, and later as a taxon, the clade is understood today in connection with Hennig's definition of a monophyletic group rather than through Huxley's successful but somehow ambiguous formalization. The inability of these authors to formulate a clear-cut exposition of the concept is considered here within three contexts: firstly, the burden of pre-Darwinian classifications based on similarity; secondly, the underestimation of Darwinâs description of a genealogical group; and thirdly, the predominance of thinking in process (vs thinking in pattern), which was the basis of evolutionary systematics in the mid-twentieth century.

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